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Ushakov A, Mamaeva K, Seleznev L, Rizaev G, Bukin V, Dolmatov T, Chizhov P, Bagdasarov V, Garnov S. Pulsed THz radiation under ultrafast optical discharge of vacuum photodiode. FRONTIERS OF OPTOELECTRONICS 2024; 17:20. [PMID: 38866994 PMCID: PMC11169299 DOI: 10.1007/s12200-024-00123-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Accepted: 05/15/2024] [Indexed: 06/14/2024]
Abstract
In this paper, we first present an experimental demonstration of terahertz radiation pulse generation with energy up to 5 pJ under the electron emission during ultrafast optical discharge of a vacuum photodiode. We use a femtosecond optical excitation of metallic copper photocathode for the generation of ultrashort electron bunch and up to 45 kV/cm external electric field for the photo-emitted electron acceleration. Measurements of terahertz pulses energy as a function of emitted charge density, incidence angle of optical radiation and applied electric field have been provided. Spectral and polarization characteristics of generated terahertz pulses have also been studied. The proposed semi-analytical model and simulations in COMSOL Multiphysics prove the experimental data and allow for the optimization of experimental conditions aimed at flexible control of radiation parameters.
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Affiliation(s)
- Aleksandr Ushakov
- Prokhorov General Physics Institute of the Russian Academy of Sciences, Moscow, 119991, Russia.
| | - Kseniia Mamaeva
- Prokhorov General Physics Institute of the Russian Academy of Sciences, Moscow, 119991, Russia
| | - Leonid Seleznev
- Physical Institute, Russian Academy of Sciences, Moscow, 119991, Russia
| | - Georgy Rizaev
- Physical Institute, Russian Academy of Sciences, Moscow, 119991, Russia
| | - Vladimir Bukin
- Prokhorov General Physics Institute of the Russian Academy of Sciences, Moscow, 119991, Russia
| | - Timophey Dolmatov
- Prokhorov General Physics Institute of the Russian Academy of Sciences, Moscow, 119991, Russia
| | - Pavel Chizhov
- Prokhorov General Physics Institute of the Russian Academy of Sciences, Moscow, 119991, Russia
- Moscow Institute of Physics and Technology, Dolgoprudny, 141700, Russia
- Russian Institute for Scientific and Technical Information, Moscow, 125190, Russia
| | - Vladimir Bagdasarov
- Prokhorov General Physics Institute of the Russian Academy of Sciences, Moscow, 119991, Russia
| | - Sergey Garnov
- Prokhorov General Physics Institute of the Russian Academy of Sciences, Moscow, 119991, Russia
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2
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Yang D, Laarman JH, Tonouchi M. Sensitive Characterization of the Graphene Transferred onto Varied Si Wafer Surfaces via Terahertz Emission Spectroscopy and Microscopy (TES/LTEM). MATERIALS (BASEL, SWITZERLAND) 2024; 17:1497. [PMID: 38612011 PMCID: PMC11012325 DOI: 10.3390/ma17071497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Revised: 03/23/2024] [Accepted: 03/24/2024] [Indexed: 04/14/2024]
Abstract
Graphene shows great potential in developing the next generation of electronic devices. However, the real implementation of graphene-based electronic devices needs to be compatible with existing silicon-based nanofabrication processes. Characterizing the properties of the graphene/silicon interface rapidly and non-invasively is crucial for this endeavor. In this study, we employ terahertz emission spectroscopy and microscopy (TES/LTEM) to evaluate large-scale chemical vapor deposition (CVD) monolayer graphene transferred onto silicon wafers, aiming to assess the dynamic electronic properties of graphene and perform large-scale graphene mapping. By comparing THz emission properties from monolayer graphene on different types of silicon substrates, including those treated with buffered oxide etches, we discern the influence of native oxide layers and surface dipoles on graphene. Finally, the mechanism of THz emission from the graphene/silicon heterojunction is discussed, and the large-scale mapping of monolayer graphene on silicon is achieved successfully. These results demonstrate the efficacy of TES/LTEM for graphene characterization in the modern graphene-based semiconductor industry.
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Affiliation(s)
- Dongxun Yang
- Institute of Laser Engineering, Osaka University, Osaka 565-0871, Japan
| | - Jesse Henri Laarman
- Department of Applied Physics, Eindhoven University of Technology, 5612 AZ Eindhoven, The Netherlands
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3
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Huang HH, Nagashima T, Hatanaka K. Shockwave-based THz emission in air. OPTICS EXPRESS 2023; 31:5650-5661. [PMID: 36823839 DOI: 10.1364/oe.478610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 12/30/2022] [Indexed: 06/18/2023]
Abstract
THz emission in air under the irradiation of a pair of tightly-focused femtosecond laser pulses (800nm, 35fs) with nanosecond time delay and micro-meter spatial offsets is studied with polarization-sensitive THz time-domain spectroscopy and time-resolved imaging. The pre-pulse irradiation induces air-breakdown at its focus, which results in the expansion of shockwave front traveling outward. When the main pulse irradiates such shockwave front far from the pre-pulse focus with nanosecond delay, THz emission intensity was enhanced up to ∼13-times and its linear polarization was aligned along the line between the two focus positions of the pre- and the main pulses which is parallel to the expansion direction of the shockwave front. Asymmetric density profiles of the shockwave fronts prepared by the pre-pulse irradiation define the polarization of THz emission. Mechanisms are discussed from the viewpoint of electron diffusion in such asymmetric density profiles.
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4
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Yang D, Mannan A, Murakami F, Tonouchi M. Rapid, noncontact, sensitive, and semiquantitative characterization of buffered hydrogen-fluoride-treated silicon wafer surfaces by terahertz emission spectroscopy. LIGHT, SCIENCE & APPLICATIONS 2022; 11:334. [PMID: 36433935 PMCID: PMC9700743 DOI: 10.1038/s41377-022-01033-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 10/25/2022] [Accepted: 11/06/2022] [Indexed: 06/16/2023]
Abstract
Advances in modern semiconductor integrated circuits have always demanded faster and more sensitive analytical methods on a large-scale wafer. The surface of wafers is fundamentally essential to start building circuits, and quantitative measures of the surface potential, defects, contamination, passivation quality, and uniformity are subject to inspection. The present study provides a new approach to access those by means of terahertz (THz) emission spectroscopy. Upon femtosecond laser illumination, THz radiation, which is sensitive to the surface electric fields of the wafer, is generated. Here, we systematically research the THz emission properties of silicon surfaces under different surface conditions, such as the initial surface with a native oxide layer, a fluorine-terminated surface, and a hydrogen-terminated surface. Meanwhile, a strong doping concentration dependence of the THz emission amplitude from the silicon surface has been revealed in different surface conditions, which implies a semiquantitative connection between the THz emission and the surface band bending with the surface dipoles. Laser-induced THz emission spectroscopy is a promising method for evaluating local surface properties on a wafer scale.
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Affiliation(s)
- Dongxun Yang
- Institute of Laser Engineering, Osaka University 2-6 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Abdul Mannan
- Institute of Laser Engineering, Osaka University 2-6 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Fumikazu Murakami
- Institute of Laser Engineering, Osaka University 2-6 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Masayoshi Tonouchi
- Institute of Laser Engineering, Osaka University 2-6 Yamadaoka, Suita, Osaka, 565-0871, Japan.
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5
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Goyal R, Tiwari A. Terahertz Conductivity of Nanoscale Materials and Systems. TERAHERTZ TECHNOLOGY 2022. [DOI: 10.5772/intechopen.104797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/27/2023]
Abstract
The history of RF technology can provide human beings a powerful lesson that the infrastructure of modern-day wireless communication depends on the complexity and configurability of silicon-based solid-state devices and integrated circuits. The field of THz technology is undergoing a developmental revolution which is at an inflection point and will bridge the ‘technology’ and ‘application’ gap in meaningful ways. This quantitative progress is a result of continuous and concerted efforts in a wide range of areas including solid-state devices, 2D materials, heterogeneous integration, nanofabrication and system packaging. In this chapter, the innovative theoretical approaches that have enabled significant advancement in the field of system-level THz technology are discussed. The focus is kept on the formulation of terahertz conductivity which plays a critical role in the modeling of devices that integrate technologies across electronics and photonics. Further, the findings build on coupling a probe pulse of terahertz illumination into the photoexcited region of amorphous silicon are presented and discussed in detail. Terahertz light has a higher penetration depth for opaque semiconductor materials which provides an accurate method to measure the conductivity of novel materials for the construction of efficient solar cells. This paves the way for the possibility to develop energy systems can address the need for reconfigurability, adaptability and scalability beyond the classical metrics.
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Bark HS, Maeng I, Kim JU, Kim KD, Na JH, Min J, Byun J, Song Y, Cha BY, Oh SJ, Ji YB. Terahertz Spectral Properties of PEO-Based Anti-Adhesion Films Cross-Linked by Electron Beam Irradiation. Polymers (Basel) 2022; 14:polym14102008. [PMID: 35631892 PMCID: PMC9147511 DOI: 10.3390/polym14102008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 05/09/2022] [Accepted: 05/11/2022] [Indexed: 01/27/2023] Open
Abstract
We investigated the spectral property changes in anti-adhesion films, which were cross-linked and surface-modified through electron beam irradiation, using terahertz time-domain spectroscopy (THz-TDS). Polyethylene oxide (PEO), which is a biocompatible and biodegradable polymer, was the main component of these anti-adhesion films being manufactured for testing. The terahertz characteristics of the films were affected by the porosity generated during the freeze-drying and compression processes of sample preparation, and this was confirmed using optical coherence tomography (OCT) imaging. An anti-adhesion polymer film made without porosity was measured by using the THz-TDS method, and it was confirmed that the refractive index and absorption coefficient were dependent on the crosslinking state. To our knowledge, this is the first experiment on the feasibility of monitoring cross-linking states using terahertz waves. The THz-TDS method has potential as a useful nondestructive technique for polymer inspection and analysis.
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Affiliation(s)
- Hyeon Sang Bark
- Radiation Center for Ultrafast Science, Korea Atomic Energy Research Institute (KAERI), Deajeon 34057, Korea;
| | - Inhee Maeng
- YUHS-KRIBB Medical Convergence Research Institute, Yonsei University College of Medicine, Seoul 03722, Korea;
| | - Jin Un Kim
- HW Tech, Yangsan 50585, Korea; (J.U.K.); (K.D.K.)
| | | | - Jae Hun Na
- Gimhae Biomedical Center, Gimhae Biomedical Industry Promotion Agency (GBIA), Gimhae 50969, Korea; (J.H.N.); (J.M.); (J.B.); (Y.S.); (B.-y.C.)
| | - Junki Min
- Gimhae Biomedical Center, Gimhae Biomedical Industry Promotion Agency (GBIA), Gimhae 50969, Korea; (J.H.N.); (J.M.); (J.B.); (Y.S.); (B.-y.C.)
| | - Jungsup Byun
- Gimhae Biomedical Center, Gimhae Biomedical Industry Promotion Agency (GBIA), Gimhae 50969, Korea; (J.H.N.); (J.M.); (J.B.); (Y.S.); (B.-y.C.)
| | - Yongkeun Song
- Gimhae Biomedical Center, Gimhae Biomedical Industry Promotion Agency (GBIA), Gimhae 50969, Korea; (J.H.N.); (J.M.); (J.B.); (Y.S.); (B.-y.C.)
| | - Byung-youl Cha
- Gimhae Biomedical Center, Gimhae Biomedical Industry Promotion Agency (GBIA), Gimhae 50969, Korea; (J.H.N.); (J.M.); (J.B.); (Y.S.); (B.-y.C.)
| | - Seung Jae Oh
- YUHS-KRIBB Medical Convergence Research Institute, Yonsei University College of Medicine, Seoul 03722, Korea;
- Correspondence: (S.J.O.); (Y.B.J.)
| | - Young Bin Ji
- Gimhae Biomedical Center, Gimhae Biomedical Industry Promotion Agency (GBIA), Gimhae 50969, Korea; (J.H.N.); (J.M.); (J.B.); (Y.S.); (B.-y.C.)
- Correspondence: (S.J.O.); (Y.B.J.)
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7
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Zhuang S, Meisenheimer PB, Heron J, Hu JM. A Narrowband Spintronic Terahertz Emitter Based on Magnetoelastic Heterostructures. ACS APPLIED MATERIALS & INTERFACES 2021; 13:48997-49006. [PMID: 34617721 DOI: 10.1021/acsami.1c13461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Narrowband terahertz (THz) radiation is crucial for high-resolution spectral identification, but a narrowband THz source driven by a femtosecond (fs) laser has remained scarce. Here, it is computationally predicted that a metal/dielectric/magnetoelastic heterostructure enables converting a fs laser pulse into a multicycle THz pulse with a narrow linewidth down to ∼1.5 GHz, which is in contrast to the single-cycle, broadband THz pulse from the existing fs-laser-excited emitters. It is shown that such narrowband THz pulse originates from the excitation and long-distance transport of THz spin waves in the magnetoelastic film, which can be enabled by a short strain pulse obtained from fs laser irradiation of the metal film when the thicknesses of the metal and magnetoelastic films both fall into a specific range. These results therefore reveal an approach to achieving optical generation of narrowband THz pulse based on heterostructure design, which also has implications in the design of THz magnonic devices.
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Affiliation(s)
- Shihao Zhuang
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53705, United States
| | - Peter B Meisenheimer
- Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - John Heron
- Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Jia-Mian Hu
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53705, United States
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8
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Ilyakov IE, Shishkin BV, Malevich VL, Ponomarev DS, Galiev RR, Pavlov AY, Yachmenev AE, Kovalev SP, Chen M, Akhmedzhanov RA, Khabibullin RA. Efficient optical-to-terahertz conversion in large-area InGaAs photo-Dember emitters with increased indium content. OPTICS LETTERS 2021; 46:3360-3363. [PMID: 34264213 DOI: 10.1364/ol.428599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 06/15/2021] [Indexed: 06/13/2023]
Abstract
In this Letter, optical-to-terahertz (THz) conversion of 800 nm femtosecond laser pulses in large-area bias-free InGaAs emitters based on photo-Dember (PD) and lateral photo-Dember (LPD) effects is experimentally investigated. We use metamorphic buffers to grow sub-micrometer thick InxGa1-xAs layers with indium mole fractions x=0.37, 0.53, and 0.70 on a GaAs substrate. A strong enhancement of THz output energy with an increase of indium content is observed. On the surface of the sample providing the strongest emission (x=0.7), we have fabricated a 1.5cm2 area of asymmetrically shaped metallic grating for LPD emission. This LPD emitter allows achieving high conversion efficiency of 0.24⋅10-3 and a broad generation bandwidth of up to 6 THz. We also demonstrate that there is no significant difference in the conversion efficiency when operating at 1 and 200 kHz repetition rates. Our results show that large-area LPD emitters give a convenient, competitive way to generate intense high-repetition-rate THz pulses.
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9
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Song C, Wang P, Qian Y, Zhou G, Nötzel R. Enhanced terahertz radiation from InAs (100) with an embedded InGaAs hole blocking layer. OPTICS EXPRESS 2020; 28:25750-25756. [PMID: 32906859 DOI: 10.1364/oe.400590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 08/06/2020] [Indexed: 06/11/2023]
Abstract
We demonstrate enhanced THz radiation from p-InAs (100) by advanced heterostructure design. The THz radiation from InAs (100) under ultra-short pulsed laser excitation is due to the photo-Dember effect. Inserting a thin n-InGaAs layer close to the InAs surface effectively blocks the hole diffusion while the electron diffusion is still efficient due to tunneling. Therefore, enhanced photogenerated electron-hole separation and photo-Dember electric field is achieved to enhance the THz emission. The layer structure and doping profile are confirmed by secondary ion mass spectrometry and X-ray diffraction. The blocking of the hole diffusion is independently verified by the surface photovoltage measured by Kelvin probe force microscopy.
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10
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Patil MR, Ganorkar SB, Patil AS, Shirkhedkar AA. Terahertz Spectroscopy: Encoding the Discovery, Instrumentation, and Applications toward Pharmaceutical Prospectives. Crit Rev Anal Chem 2020; 52:343-355. [PMID: 32772866 DOI: 10.1080/10408347.2020.1802219] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Terahertz (THz) spectroscopy is an emerging field for quality control of pharmaceuticals, which uses T-waves for detection. T-waves fall in between infrared and microwave radiations while possessing some of the characteristics of both. THz spectroscopy reveals its existence in between 0.1 and 10 THz. These radiations have the ability to penetrate a broad range of non-conductive materials and it is nonionizing. The first article stating the use of THz radiations was found in late 1960 for the generation of the astronomical images. This review essentially creates attention toward different forms and instrumentation of THz spectroscopy along with the updates for timely and upbeat pharmaceutical applications. The most frequently used technique is THz-TDS which has profoundly privileged applicability for the pharmaceuticals. The existing literature of THz spectroscopy further created albeit interest to explore the applications for future implementation in concern with the pharmaceuticals. The review critically outlines here all the pharmaceutical applications of THz spectroscopy including protein analyses, crystallinity studies, evaluating tablet films and coats, medicinal aging variations, and detection of illicit drugs, along with the advantages over traditional techniques. The other side of THz spectroscopy stating limitations is also studied and taken into the note to present here. This review is a genuine attempt to quote and crucially assess the possible as well as anticipated prospectives for the pharmaceuticals. The present article will further promote the awareness, opportunities, and scientific exploration of this exciting technology as THz spectroscopy.
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Affiliation(s)
- Mangesh R Patil
- Central Instruments Facility(CIF), Department of Pharmaceutical Chemistry, R. C. Patel Institute of Pharmaceutical Education and Research, Shirpur, Maharashtra, India
| | - Saurabh B Ganorkar
- Central Instruments Facility(CIF), Department of Pharmaceutical Chemistry, R. C. Patel Institute of Pharmaceutical Education and Research, Shirpur, Maharashtra, India
| | - Amod S Patil
- Central Instruments Facility(CIF), Department of Pharmaceutical Chemistry, R. C. Patel Institute of Pharmaceutical Education and Research, Shirpur, Maharashtra, India
| | - Atul A Shirkhedkar
- Central Instruments Facility(CIF), Department of Pharmaceutical Chemistry, R. C. Patel Institute of Pharmaceutical Education and Research, Shirpur, Maharashtra, India
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11
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Huang Y, Yao Z, He C, Zhu L, Zhang L, Bai J, Xu X. Terahertz surface and interface emission spectroscopy for advanced materials. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:153001. [PMID: 30669133 DOI: 10.1088/1361-648x/ab00c0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Surfaces and interfaces are of particular importance for optoelectronic and photonic materials as they are involved in many physical and chemical processes such as carrier dynamics, charge transfer, chemical bonding, transformation reactions and so on. Terahertz (THz) emission spectroscopy provides a sensitive and nondestructive method for surface or interface analysis of advanced materials ranging from graphene to transition metal dichalcogenides, topological insulators, hybrid perovskites, and mixed-dimensional heterostructures based on 2D materials. In this review paper, we start with the THz radiation mechanisms under ultrafast laser excitation. Then we concentrate on the recent progresses of THz emission spectroscopy on the surface and interface properties of advanced materials, including transient surface photocurrents, surface nonlinear polarization, surface states, interface potential, and gas molecule adsorption/desorption processes. This novel spectroscopic method can not only promote the development of new and compact THz sources, but also provide a nondestructive optical method for surface and interface characterization of photocurrent and nonlinear polarization dynamics of materials.
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Affiliation(s)
- Yuanyuan Huang
- Shaanxi Joint Lab of Graphene, State Key Lab Incubation Base of Photoelectric Technology and Functional Materials, International Collaborative Center on Photoelectric Technology and Nano Functional Materials, Institute of Photonics and Photon-Technology, Northwest University, Xi'an 710069, People's Republic of China
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12
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Guzelturk B, Belisle RA, Smith MD, Bruening K, Prasanna R, Yuan Y, Gopalan V, Tassone CJ, Karunadasa HI, McGehee MD, Lindenberg AM. Terahertz Emission from Hybrid Perovskites Driven by Ultrafast Charge Separation and Strong Electron-Phonon Coupling. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30. [PMID: 29359820 DOI: 10.1002/adma.201704737] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2017] [Revised: 12/21/2017] [Indexed: 05/06/2023]
Abstract
Unusual photophysical properties of organic-inorganic hybrid perovskites have not only enabled exceptional performance in optoelectronic devices, but also led to debates on the nature of charge carriers in these materials. This study makes the first observation of intense terahertz (THz) emission from the hybrid perovskite methylammonium lead iodide (CH3 NH3 PbI3 ) following photoexcitation, enabling an ultrafast probe of charge separation, hot-carrier transport, and carrier-lattice coupling under 1-sun-equivalent illumination conditions. Using this approach, the initial charge separation/transport in the hybrid perovskites is shown to be driven by diffusion and not by surface fields or intrinsic ferroelectricity. Diffusivities of the hot and band-edge carriers along the surface normal direction are calculated by analyzing the emitted THz transients, with direct implications for hot-carrier device applications. Furthermore, photogenerated carriers are found to drive coherent terahertz-frequency lattice distortions, associated with reorganizations of the lead-iodide octahedra as well as coupled vibrations of the organic and inorganic sublattices. This strong and coherent carrier-lattice coupling is resolved on femtosecond timescales and found to be important both for resonant and far-above-gap photoexcitation. This study indicates that ultrafast lattice distortions play a key role in the initial processes associated with charge transport.
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Affiliation(s)
- Burak Guzelturk
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Rebecca A Belisle
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Matthew D Smith
- Department of Chemistry, Stanford University, Stanford, CA, 94305, USA
| | - Karsten Bruening
- SSRL Materials Science Division, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Rohit Prasanna
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Yakun Yuan
- Department of Materials Science and Engineering, Pennsylvania State, University Park, PA, 16802, USA
| | - Venkatraman Gopalan
- Department of Materials Science and Engineering, Pennsylvania State, University Park, PA, 16802, USA
| | - Christopher J Tassone
- SSRL Materials Science Division, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | | | - Michael D McGehee
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Aaron M Lindenberg
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
- Department of Photon Science, Stanford University and SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
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13
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Smolyanskaya OA, Schelkanova IJ, Kulya MS, Odlyanitskiy EL, Goryachev IS, Tcypkin AN, Grachev YV, Toropova YG, Tuchin VV. Glycerol dehydration of native and diabetic animal tissues studied by THz-TDS and NMR methods. BIOMEDICAL OPTICS EXPRESS 2018; 9. [PMID: 29541513 PMCID: PMC5846523 DOI: 10.1364/boe.9.001198] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The optical clearing method has been widely used for different spectral ranges where it provides tissue transparency. In this work, we observed the enhanced penetration of the terahertz waves inside biological samples (skin, kidney, and cornea) treated with glycerol solutions inducing changes of optical and dielectric properties. It was supported by the observed trend of free-to-bound water ratio measured by the nuclear magnetic resonance (NMR) method. The terahertz clearing efficiency was found to be less for diabetic samples than for normal ones. Results of the numerical simulation proved that pulse deformation is due to bigger penetration depth caused by the reduction of absorption and refraction at optical clearing.
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Affiliation(s)
| | | | - M S Kulya
- ITMO University, Saint-Petersburg 197101, Russia
| | | | | | - A N Tcypkin
- ITMO University, Saint-Petersburg 197101, Russia
| | - Ya V Grachev
- ITMO University, Saint-Petersburg 197101, Russia
| | - Ya G Toropova
- Almazov National Medical Research Centre, IEM, Saint-Petersburg 197341, Russia
| | - V V Tuchin
- ITMO University, Saint-Petersburg 197101, Russia
- Saratov State University (National Research University), Saratov 410012, Russia
- Institute of Precision Mechanics and Control RAS, Saratov 410028, Russia
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14
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Seifert P, Vaklinova K, Kern K, Burghard M, Holleitner A. Surface State-Dominated Photoconduction and THz Generation in Topological Bi 2Te 2Se Nanowires. NANO LETTERS 2017; 17:973-979. [PMID: 28081604 PMCID: PMC5338589 DOI: 10.1021/acs.nanolett.6b04312] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 01/12/2017] [Indexed: 06/04/2023]
Abstract
Topological insulators constitute a fascinating class of quantum materials with nontrivial, gapless states on the surface and insulating bulk states. By revealing the optoelectronic dynamics in the whole range from femto- to microseconds, we demonstrate that the long surface lifetime of Bi2Te2Se nanowires allows us to access the surface states by a pulsed photoconduction scheme and that there is a prevailing bolometric response of the surface states. The interplay of the surface and bulk states dynamics on the different time scales gives rise to a surprising physical property of Bi2Te2Se nanowires: their pulsed photoconductance changes polarity as a function of laser power. Moreover, we show that single Bi2Te2Se nanowires can be used as THz generators for on-chip high-frequency circuits at room temperature. Our results open the avenue for single Bi2Te2Se nanowires as active modules in optoelectronic high-frequency and THz circuits.
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Affiliation(s)
- Paul Seifert
- Walter Schottky
Institut and Physik-Department, Technische
Universität München, Am Coulombwall 4a, D-85748 Garching, Germany
| | - Kristina Vaklinova
- Max-Planck-Institut
für Festkörperforschung, Heisenbergstraße 1, D-70569 Stuttgart, Germany
| | - Klaus Kern
- Max-Planck-Institut
für Festkörperforschung, Heisenbergstraße 1, D-70569 Stuttgart, Germany
- Institut de Physique, Ecole Polytechnique Fédérale
de Lausanne, CH-1015 Lausanne, Switzerland
| | - Marko Burghard
- Max-Planck-Institut
für Festkörperforschung, Heisenbergstraße 1, D-70569 Stuttgart, Germany
| | - Alexander Holleitner
- Walter Schottky
Institut and Physik-Department, Technische
Universität München, Am Coulombwall 4a, D-85748 Garching, Germany
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15
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Generation of radially-polarized terahertz pulses for coupling into coaxial waveguides. Sci Rep 2016; 6:38926. [PMID: 27941845 PMCID: PMC5150854 DOI: 10.1038/srep38926] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Accepted: 11/15/2016] [Indexed: 11/24/2022] Open
Abstract
Coaxial waveguides exhibit no dispersion and therefore can serve as an ideal channel for transmission of broadband THz pulses. Implementation of THz coaxial waveguide systems however requires THz beams with radially-polarized distribution. We demonstrate the launching of THz pulses into coaxial waveguides using the effect of THz pulse generation at semiconductor surfaces. We find that the radial transient photo-currents produced upon optical excitation of the surface at normal incidence radiate a THz pulse with the field distribution matching the mode of the coaxial waveguide. In this simple scheme, the optical excitation beam diameter controls the spatial profile of the generated radially-polarized THz pulse and allows us to achieve efficient coupling into the TEM waveguide mode in a hollow coaxial THz waveguide. The TEM quasi-single mode THz waveguide excitation and non-dispersive propagation of a short THz pulse is verified experimentally by time-resolved near-field mapping of the THz field at the waveguide output.
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16
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Improvement of Terahertz Wave Radiation for InAs Nanowires by Simple Dipping into Tap Water. Sci Rep 2016; 6:36094. [PMID: 27782220 PMCID: PMC5080572 DOI: 10.1038/srep36094] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 10/10/2016] [Indexed: 11/30/2022] Open
Abstract
We report improvement of terahertz (THz) wave radiation for Si-based catalyst-free InAs nanowires (NWs) by simple dipping into tap water (DTW). In addition, the possibility of using InAs NWs as a cost-effective method for biomedical applications is discussed by comparison to bulk InAs. The peak-to-peak current signals (PPCSs) of InAs NWs measured from THz time-domain spectroscopy increased with increasing NW height. For example, the PPCS of 10 μm-long InAs NWs was 2.86 times stronger than that of 2.1 μm-long NWs. The THz spectra of the InAs NWs obtained by applying a fast Fourier transformation to the current signals showed a main frequency of 0.5 THz, which can be applied to a variety of medical imaging systems. After the DTW process, structural variation was not observed for 2.1 μm-long InAs NWs. However, the top region of several InAs NWs with heights of 4.6 and 5.8 μm merged into a conical structure. InAs NWs with a height of 10 μm resulted in a bundle feature forming above the conical shape, where the length of bundle region was 4 μm. After the DTW process, the PPCS for 10 μm-long InAs NWs increased by 15 percent compared to that of the as-grown case.
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17
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Ji YB, Moon IS, Bark HS, Kim SH, Park DW, Noh SK, Huh YM, Suh JS, Oh SJ, Jeon TI. Terahertz otoscope and potential for diagnosing otitis media. BIOMEDICAL OPTICS EXPRESS 2016; 7:1201-9. [PMID: 27446647 PMCID: PMC4929633 DOI: 10.1364/boe.7.001201] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Revised: 03/03/2016] [Accepted: 03/06/2016] [Indexed: 05/21/2023]
Abstract
We designed and fabricated a novel terahertz (THz) otoscope to help physicians to diagnose otitis media (OM) with both THz diagnostics and conventional optical diagnostics. We verified the potential of this tool for diagnosing OM using mouse skin tissue and a human tympanic membrane samples prior to clinical application.
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Affiliation(s)
- Young Bin Ji
- YUHS-KRIBB Medical Convergence Research Institute, Yonsei University College of Medicine, Seoul 120-752, South Korea
- These authors contributed equally to this work
| | - In-Seok Moon
- Department of Otorhinolaryngology, Yonsei University College of Medicine, Seoul 120-752, South Korea
- These authors contributed equally to this work
| | - Hyeon Sang Bark
- Division of Electrical and Electronics Engineering, Korea Maritime and Ocean University, Busan 606-791, South Korea
| | - Sang Hoon Kim
- YUHS-KRIBB Medical Convergence Research Institute, Yonsei University College of Medicine, Seoul 120-752, South Korea
| | - Dong Woo Park
- Divsion of Advanced Materials Engineering, Chonbuk National University, Jeonju 561-756, South Korea
- Nano Materials Evaluation Center, Korea Research Institute of Standards and Science, Daejeon 305-340, South Korea
| | - Sam Kyu Noh
- Nano Materials Evaluation Center, Korea Research Institute of Standards and Science, Daejeon 305-340, South Korea
| | - Yong-Min Huh
- YUHS-KRIBB Medical Convergence Research Institute, Yonsei University College of Medicine, Seoul 120-752, South Korea
- Department of Radiology, Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul 120-752, South Korea
| | - Jin-Seok Suh
- YUHS-KRIBB Medical Convergence Research Institute, Yonsei University College of Medicine, Seoul 120-752, South Korea
- Department of Radiology, Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul 120-752, South Korea
| | - Seung Jae Oh
- YUHS-KRIBB Medical Convergence Research Institute, Yonsei University College of Medicine, Seoul 120-752, South Korea
| | - Tae-In Jeon
- Division of Electrical and Electronics Engineering, Korea Maritime and Ocean University, Busan 606-791, South Korea
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18
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Mohammad-Zamani MJ, Neshat M, Moravvej-Farshi MK. Nanoslit cavity plasmonic modes and built-in fields enhance the CW THz radiation in an unbiased antennaless photomixers array. OPTICS LETTERS 2016; 41:420-423. [PMID: 26766729 DOI: 10.1364/ol.41.000420] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
A new generation unbiased antennaless CW terahertz (THz) photomixer emitters array made of asymmetric metal-semiconductor-metal (MSM) gratings with a subwavelength pitch, operating in the optical near-field regime, is proposed. We take advantage of size effects in near-field optics and electrostatics to demonstrate the possibility of enhancing the THz power by 4 orders of magnitude, compared to a similar unbiased antennaless array of the same size that operates in the far-field regime. We show that, with the appropriate choice of grating parameters in such THz sources, the first plasmonic resonant cavity mode in the nanoslit between two adjacent MSMs can enhance the optical near-field absorption and, hence, the generation of photocarriers under the slit in the active medium. These photocarriers, on the other hand, are accelerated by the large built-in electric field sustained under the nanoslits by two dissimilar Schottky barriers to create the desired large THz power that is mainly radiated downward. The proposed structure can be tuned in a broadband frequency range of 0.1-3 THz, with output power increasing with frequency.
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19
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Erhard N, Zenger S, Morkötter S, Rudolph D, Weiss M, Krenner HJ, Karl H, Abstreiter G, Finley JJ, Koblmüller G, Holleitner AW. Ultrafast Photodetection in the Quantum Wells of Single AlGaAs/GaAs-Based Nanowires. NANO LETTERS 2015; 15:6869-6874. [PMID: 26356189 DOI: 10.1021/acs.nanolett.5b02766] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We investigate the ultrafast optoelectronic properties of single Al0.3Ga0.7As/GaAs core-shell nanowires. The nanowires contain GaAs-based quantum wells. For a resonant excitation of the quantum wells, we find a picosecond photocurrent which is consistent with an ultrafast lateral expansion of the photogenerated charge carriers. This Dember-effect does not occur for an excitation of the GaAs-based core of the nanowires. Instead, the core exhibits an ultrafast displacement current and a photothermoelectric current at the metal Schottky contacts. Our results uncover the optoelectronic dynamics in semiconductor core-shell nanowires comprising quantum wells, and they demonstrate the possibility to use the low-dimensional quantum well states therein for ultrafast photoswitches and photodetectors.
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Affiliation(s)
- N Erhard
- Nanosystems Initiative Munich (NIM), Schellingstr. 4, D-80799 München, Germany
| | | | | | | | - M Weiss
- Nanosystems Initiative Munich (NIM), Schellingstr. 4, D-80799 München, Germany
- Institute of Physics, Universität Augsburg , Universitätsstr. 1, D-86135 Augsburg, Germany
| | - H J Krenner
- Nanosystems Initiative Munich (NIM), Schellingstr. 4, D-80799 München, Germany
- Institute of Physics, Universität Augsburg , Universitätsstr. 1, D-86135 Augsburg, Germany
| | - H Karl
- Institute of Physics, Universität Augsburg , Universitätsstr. 1, D-86135 Augsburg, Germany
| | - G Abstreiter
- Nanosystems Initiative Munich (NIM), Schellingstr. 4, D-80799 München, Germany
| | - J J Finley
- Nanosystems Initiative Munich (NIM), Schellingstr. 4, D-80799 München, Germany
| | | | - A W Holleitner
- Nanosystems Initiative Munich (NIM), Schellingstr. 4, D-80799 München, Germany
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20
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Mohammad-Zamani MJ, Moravvej-Farshi MK, Neshat M. Unbiased continuous wave terahertz photomixer emitters with dis-similar Schottky barriers. OPTICS EXPRESS 2015; 23:19129-19141. [PMID: 26367576 DOI: 10.1364/oe.23.019129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We are introducing a new bias free CW terahertz photomixer emitter array. Each emitter consists of an asymmetric metal-semiconductor-metal (MSM) that is made of two side by side dis-similar Schottky contacts, on a thin layer of low temperature grown (LTG) GaAs, with barrier heights of difference (ΔΦ(B)) and a finite lateral spacing (s). Simulations show that when an appropriately designed structure is irradiated by two coherent optical beams of different center wavelengths, whose frequency difference (∆f) falls in a desired THz band, the built-in field between the two dis-similar potential barriers can accelerate the photogenerated carriers that are modulated by ∆ω, making each pitch in the array to act as a CW THz emitter, effectively. We also show the permissible values of s and ΔΦ(B) pairs, for which the strengths of the built-in electric field maxima fall below that of the critical of 50 V/μm- i.e., the breakdown limit for the LTG-GaAs layer. Moreover, we calculate the THz radiation power per emitter in an array. Among many potential applications for these bias free THz emitters their use in endoscopic imaging without a need for hazardous external biasing circuitry that reduces the patient health risk, could be the most important one. A hybrid numerical simulation method is used to design an optimum emitter pitch, radiating at 0.5 THz.
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21
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Liu CH, Chang YC, Lee S, Zhang Y, Zhang Y, Norris TB, Zhong Z. Ultrafast Lateral Photo-Dember Effect in Graphene Induced by Nonequilibrium Hot Carrier Dynamics. NANO LETTERS 2015; 15:4234-4239. [PMID: 25993273 DOI: 10.1021/acs.nanolett.5b01912] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The photo-Dember effect arises from the asymmetric diffusivity of photoexcited electrons and holes, which creates a transient spatial charge distribution and hence the buildup of a voltage. Conventionally, a strong photo-Dember effect is only observed in semiconductors with a large asymmetry between the electron and hole mobilities, such as in GaAs or InAs, and is considered negligible in graphene due to its electron-hole symmetry. Here, we report the observation of a strong lateral photo-Dember effect induced by nonequilibrium hot carrier dynamics when exciting a graphene-metal interface with a femtosecond laser. Scanning photocurrent measurements reveal the extraction of photoexcited hot carriers is driven by the transient photo-Dember field, and the polarity of the photocurrent is determined by the device's mobility asymmetry. Furthermore, ultrafast pump-probe measurements indicate the magnitude of photocurrent is related to the hot carrier cooling rate. Our simulations also suggest that the lateral photo-Dember effect originates from graphene's 2D nature combined with its unique electrical and optical properties. Taken together, these results not only reveal a new ultrafast photocurrent generation mechanism in graphene but also suggest new types of terahertz sources based on 2D nanomaterials.
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Affiliation(s)
- Chang-Hua Liu
- †Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - You-Chia Chang
- ‡Center for Photonics and Multiscale Nanomaterials, University of Michigan, Ann Arbor, Michigan 48109, United States
- §Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Seunghyun Lee
- †Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Yaozhong Zhang
- ∥Key Laboratory for Thin Film and Microfabrication of the Ministry of Education, Research Institute of Micro/Nano Science and Technology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Yafei Zhang
- ∥Key Laboratory for Thin Film and Microfabrication of the Ministry of Education, Research Institute of Micro/Nano Science and Technology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Theodore B Norris
- †Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109, United States
- ‡Center for Photonics and Multiscale Nanomaterials, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Zhaohui Zhong
- †Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109, United States
- ‡Center for Photonics and Multiscale Nanomaterials, University of Michigan, Ann Arbor, Michigan 48109, United States
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22
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McBryde D, Barnes ME, Berry SA, Gow P, Beere HE, Ritchie DA, Apostolopoulos V. Fluence and polarisation dependence of GaAs based Lateral Photo-Dember terahertz emitters. OPTICS EXPRESS 2014; 22:3234-3243. [PMID: 24663615 DOI: 10.1364/oe.22.003234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We characterise THz output of lateral photo-Dember (LPD) emitters based on semi-insulating (SI), unannealed and annealed low temperature grown (LTG) GaAs. Saturation of THz pulse power with optical fluence is observed, with unannealed LTG GaAs showing highest saturation fluence at 1.1 ± 0.1 mJ cm(-2). SI-GaAs LPD emitters show a flip in signal polarity with optical fluence that is attributed to THz emission from the metal-semiconductor contact. Variation in optical polarisation affects THz pulse power that is attributed to a local optical excitation near the metal contact.
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23
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Yim JH, Jeong H, Irfan M, Lee EH, Song JD, Jho YD. Directional terahertz emission from corrugated InAs structures. OPTICS EXPRESS 2013; 21:19709-19717. [PMID: 24105518 DOI: 10.1364/oe.21.019709] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The terahertz (THz) radiation from transient dipoles, formed by distinct diffusion coefficients between oppositely charged carriers as often observed in low band gap semiconductors, propagates with an anisotropic amplitude distribution perpendicular to the dipole axis along the diffusive motion. By directionally adjusting the electronic diffusion, we conceptualize groove-patterned THz emitters based on (100) InAs thin films and demonstrate the unidirectional radiation. Line-of-sight emission along the surface-normal direction is greatly enhanced in a distributed asymmetric trapezoid with its period similar to the electronic diffusion length of InAs. This directional enhancement is in clear contrast to the constant emission amplitude along the lateral direction, regardless of pattern scale, which manifests the role of groove patterns as microscale reflectors in laterally corrugating the carrier density. In contrast to the rather limited nonlinearity in (100) plane, the azimuthal angle dependence of the THz field amplitude in corrugated samples shows a combined effect of diffusive transport and second-order nonlinearity, whose compositional contributions varies in different structures.
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24
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Barnes ME, Berry SA, Gow P, McBryde D, Daniell GJ, Beere HE, Ritchie DA, Apostolopoulos V. Investigation of the role of the lateral photo-Dember effect in the generation of terahertz radiation using a metallic mask on a semiconductor. OPTICS EXPRESS 2013; 21:16263-16272. [PMID: 23938477 DOI: 10.1364/oe.21.016263] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Pulses of coherent terahertz radiation can be efficiently generated by a lateral diffusion current after ultrafast generation of photo-carriers near a metal interface on the surface of a semiconductor, this is known as the lateral photo-Dember effect. We investigate how the emission depends on the pump spot position, size, power and how it is affected by the application of an applied external bias. We study the role of the metallic mask and how it suppresses emission from the carriers diffusing under it due to a reduction of available radiation states both theoretically and experimentally.
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Affiliation(s)
- M E Barnes
- School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ, United Kingdom.
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25
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Ramakrishnan G, Ramanandan GKP, Adam AJL, Xu M, Kumar N, Hendrikx RWA, Planken PCM. Enhanced terahertz emission by coherent optical absorption in ultrathin semiconductor films on metals. OPTICS EXPRESS 2013; 21:16784-16798. [PMID: 23938530 DOI: 10.1364/oe.21.016784] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We report on the surprisingly strong, broadband emission of coherent terahertz pulses from ultrathin layers of semiconductors such as amorphous silicon, germanium and polycrystalline cuprous oxide deposited on gold, upon illumination with femtosecond laser pulses. The strength of the emission is surprising because the materials are considered to be bad (amorphous silicon and polycrystalline cuprous oxide) or fair (amorphous germanium) terahertz emitters at best. We show that the strength of the emission is partly explained by cavity-enhanced optical absorption. This forces most of the light to be absorbed in the depletion region of the semiconductor/metal interface where terahertz generation occurs. For an excitation wavelength of 800 nm, the strongest terahertz emission is found for a 25 nm thick layer of amorphous germanium, a 40 nm thick layer of amorphous silicon and a 420 nm thick layer of cuprous oxide, all on gold. The emission from cuprous oxide is similar in strength to that obtained with optical rectification from a 300 μm thick gallium phosphide crystal. As an application of our findings we demonstrate how such thin films can be used to turn standard optical components, such as paraboloidal mirrors, into self-focusing terahertz emitters.
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Affiliation(s)
- Gopakumar Ramakrishnan
- Optics Research Group, Department of Imaging Science and Technology, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands.
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26
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Mittendorff M, Xu M, Dietz RJB, Künzel H, Sartorius B, Schneider H, Helm M, Winnerl S. Large area photoconductive terahertz emitter for 1.55 μm excitation based on an InGaAs heterostructure. NANOTECHNOLOGY 2013; 24:214007. [PMID: 23619031 DOI: 10.1088/0957-4484/24/21/214007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We present scalable large area terahertz (THz) emitters based on a nanoscale multilayer InGaAs/InAlAs heterostructure and a microstructured electrode pattern. The emitters are designed for pump lasers working at the telecommunication wavelength of 1.55 μm. Electric THz fields of more than 2.5 V cm⁻¹ are reached with moderate pump powers of 80 mW, the corresponding spectrum extends up to 3 THz. The saturation characteristics have been investigated for different pump laser spot sizes. For small pump powers of less than 50 mW the emitted THz field is nearly independent of the spot size, for higher pump powers and small spot sizes a clear saturation of the generated THz pulse can be observed. Hence the use of scalable emitters is especially promising for high power fibre laser systems. The spectral content of the generated radiation is nearly independent of the parameters spot size, pump power, and bias voltage, which allows for stable operation in spectroscopic applications.
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Affiliation(s)
- Martin Mittendorff
- Helmholtz-Zentrum Dresden-Rossendorf, PO Box 510119, D-01314 Dresden, Germany.
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27
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Antsygin VD, Konchenko AS, Korol’kov VP, Mamrashev AA, Nikolaev NA, Potaturkin OI. Terahertz microlens array emitter based on the transverse Dember cross effect. ACTA ACUST UNITED AC 2013. [DOI: 10.3103/s8756699013020118] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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28
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29
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Qiao W, Stephan D, Hasselbeck M, Liang Q, Dekorsy T. Low-temperature THz time domain waveguide spectrometer with butt-coupled emitter and detector crystal. OPTICS EXPRESS 2012; 20:19769-19777. [PMID: 23037029 DOI: 10.1364/oe.20.019769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
A compact high-resolution THz time-domain waveguide spectrometer that is operated inside a cryostat is demonstrated. A THz photo-Dember emitter and a ZnTe electro-optic detection crystal are directly attached to a parallel copper-plate waveguide. This allows the THz beam to be excited and detected entirely inside the cryostat, obviating the need for THz-transparent windows or external THz mirrors. Since no external bias for the emitter is required, no electric feed-through into the cryostat is necessary. Using asynchronous optical sampling, high resolution THz spectra are obtained in the frequency range from 0.2 to 2.0 THz. The THz emission from the photo-Dember emitter and the absorption spectrum of 1,2-dicyanobenzene film are measured as a function of temperature. An absorption peak around 750 GHz of 1,2-dicyanobenzene displays a blue shift with increasing temperature.
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Affiliation(s)
- W Qiao
- Department of Physics and Center for Applied Photonics, University of Konstanz, D-78457 Konstanz, Germany
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30
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Lee K, Yi M, Song JD, Ahn J. Polarization shaping of few-cycle terahertz waves. OPTICS EXPRESS 2012; 20:12463-12472. [PMID: 22714234 DOI: 10.1364/oe.20.012463] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We present a polarization shaping technique for few-cycle terahertz (THz) waves. For this, N femtosecond laser pulses are generated from a devised diffractive optical system made of as-many glass wedges, which then simultaneously illuminate on various angular positions of a sub-wavelength circular pattern of an indium arsenide thin film, to produce a THz wave of tailor-made polarization state given as a superposition of N linearly-polarized THz pulses. By properly arranging the orientation and thickness of the glass wedges, which determine the polarization and its timing of the constituent THz pulses, we successfully generate THz waves of various unconventional polarization states, such as polarization rotation and alternation between circular polarization states.
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Affiliation(s)
- Kanghee Lee
- Department of Physics, KAIST, Daejeon 305-701, Korea
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31
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Barnes ME, McBryde D, Daniell GJ, Whitworth G, Chung AL, Quarterman AH, Wilcox KG, Brewer A, Beere HE, Ritchie DA, Apostolopoulos V. Terahertz emission by diffusion of carriers and metal-mask dipole inhibition of radiation. OPTICS EXPRESS 2012; 20:8898-8906. [PMID: 22513600 DOI: 10.1364/oe.20.008898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Terahertz (THz) radiation can be generated by ultrafast photo-excitation of carriers in a semiconductor partly masked by a gold surface. A simulation of the effect taking into account the diffusion of carriers and the electric field shows that the total net current is approximately zero and cannot account for the THz radiation. Finite element modelling and analytic calculations indicate that the THz emission arises because the metal inhibits the radiation from part of the dipole population, thus creating an asymmetry and therefore a net current. Experimental investigations confirm the simulations and show that metal-mask dipole inhibition can be used to create THz emitters.
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Affiliation(s)
- M E Barnes
- School of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ, UK
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32
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Wahlstrand JK, Zhang H, Choi SB, Sipe JE, Cundiff ST. Electric field-induced coherent control in GaAs: polarization dependence and electrical measurement [Invited]. OPTICS EXPRESS 2011; 19:22563-22574. [PMID: 22109135 DOI: 10.1364/oe.19.022563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
A static electric field enables coherent control of the photoexcited carrier density in a semiconductor through the interference of one- and two-photon absorption. An experiment using optical detection is described. The polarization dependence of the signal is consistent with a calculation using a 14-band k · p model for GaAs. We also describe an electrical measurement. A strong enhancement of the phase-dependent photocurrent through a metal-semiconductor-metal structure is observed when a bias of a few volts is applied. The dependence of the signal on bias and laser spot position is studied. The field-induced enhancement of the signal could increase the sensitivity of semiconductor-based carrier-envelope phase detectors, useful in stabilizing mode-locked lasers for use in frequency combs.
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Affiliation(s)
- J K Wahlstrand
- JILA, National Institute of Standards and Technology and the University of Colorado, Boulder, CO 80309-0440, USA
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33
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Affiliation(s)
- Jason B. Baxter
- Department of Chemical and Biological Engineering, Drexel University, Philadelphia, Pennsylvania, 19104, United States
| | - Glenn W. Guglietta
- Department of Chemical and Biological Engineering, Drexel University, Philadelphia, Pennsylvania, 19104, United States
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34
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Bakunov MI, Mikhaylovskiy RV, Tani M. Strong interference enhancement of terahertz emission from a photoexcited semiconductor surface. OPTICS EXPRESS 2010; 18:22406-22411. [PMID: 20941140 DOI: 10.1364/oe.18.022406] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
To enhance terahertz emission from an optically excited semiconductor surface, we propose to sandwich a thin (as compared to the terahertz wavelength) semiconductor layer between a dielectric hyperhemispherical lens and metal substrate. The layer is excited through the lens. The substrate provides constructive interference of terahertz waves emitted to the lens directly from the layer and reflected by the substrate. The lens outcouples terahertz radiation into free space. For InAs layer sandwiched between MgO (or sapphire) lens and metal substrate, our theory predicts order of magnitude increase in the terahertz yield as compared to the previous schemes of terahertz emission from semiconductor surfaces.
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Affiliation(s)
- M I Bakunov
- University of Nizhny Novgorod, Nizhny Novgorod 603950, Russia.
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Beck M, Schäfer H, Klatt G, Demsar J, Winnerl S, Helm M, Dekorsy T. Impulsive terahertz radiation with high electric fields from an amplifier-driven large-area photoconductive antenna. OPTICS EXPRESS 2010; 18:9251-9257. [PMID: 20588772 DOI: 10.1364/oe.18.009251] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We report on the generation of impulsive terahertz (THz) radiation with 36 kV/cm vacuum electric field (1.5 mW average thermal power) at 250 kHz repetition rate and a high NIR-to-THz conversion efficiency of 2 x 10(-3). This is achieved by photoexciting biased large-area photoconductive emitter with NIR fs pulses of microJ pulse energy. We demonstrate focussing of the THz beam by tailoring the pulse front of the exciting laser beam without any focussing element for the THz beam. A high dynamic range of 10(4) signal-to-noise is obtained with an amplifier based system.
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Affiliation(s)
- M Beck
- Department of Physics and Center for Applied Photonics, University of Konstanz, D-78457 Konstanz, Germany.
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