1
|
Khanmohammadi S, Kushnir Friedman K, Chen E, Kastuar SM, Ekuma CE, Koski KJ, Titova LV. Tailoring Ultrafast Near-Band Gap Photoconductive Response in GeS by Zero-Valent Cu Intercalation. ACS APPLIED MATERIALS & INTERFACES 2024; 16:16445-16452. [PMID: 38528798 DOI: 10.1021/acsami.3c19251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/27/2024]
Abstract
Zero-valent intercalation of atomic metals into the van der Waals gap of layered materials can be used to tune their electronic, optical, thermal, and mechanical properties. Here, we report the impact of intercalating ∼3 atm percent of zero-valent copper into germanium sulfide (GeS). Advanced many-body calculations predict that copper introduces quasi-localized intermediate band states, and time-resolved THz spectroscopy studies demonstrate that those states have prominent effects on the photoconductivity of GeS. Cu-intercalated GeS exhibits a faster rise of transient photoconductivity and a shorter lifetime of optically injected carriers following near-gap excitation with 800 nm pulses. At the same time, Cu intercalation improves free carrier mobility from 1100 to 1300 cm2 V-1 s-1, which we attribute to the damping of acoustic phonons observed in Brillouin scattering and consequent reduction of phonon scattering.
Collapse
Affiliation(s)
- Sepideh Khanmohammadi
- Department of Physics, Worcester Polytechnic Institute, Worcester, Massachusetts 01609, United States
| | - Kateryna Kushnir Friedman
- Department of Physics, Worcester Polytechnic Institute, Worcester, Massachusetts 01609, United States
| | - Ethan Chen
- Department of Chemistry, University of California Davis, Davis, California 95616, United States
| | - Srihari M Kastuar
- Department of Physics, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Chinedu E Ekuma
- Department of Physics, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Kristie J Koski
- Department of Chemistry, University of California Davis, Davis, California 95616, United States
| | - Lyubov V Titova
- Department of Physics, Worcester Polytechnic Institute, Worcester, Massachusetts 01609, United States
| |
Collapse
|
2
|
Wang X, Weng J, Xu M, Li X, Yang T, Hou Y, Shen J, Zhang B. Morphology engineering of a hybrid perovskite for active terahertz memory modulation. OPTICS EXPRESS 2022; 30:2626-2635. [PMID: 35209398 DOI: 10.1364/oe.449984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 01/03/2022] [Indexed: 06/14/2023]
Abstract
Morphology engineering was investigated for hybrid perovskites CH3NH3PbI3:Ag/Poly(3, 4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) that were fabricated in both air and nitrogen environments for active terahertz (THz) memory modulation. Under low optical excitation or an applied bias, THz amplitude modulation or rapid restore in both CH3NH3PbI3:Ag/PEDOT:PSS hybrid structures were demonstrated. The recovery time of the modulated THz wave in the sample fabricated in air was considerably longer than that of the sample fabricated in nitrogen because of defect states induced by a high degree of roughness. THz transmissions were used as coded pixel units and were programmed to store a 4×4 image or a multi-order signal. Hence, active THz memory modulation was demonstrated. It also has potential applications as a visible to near-infrared broad-spectrum light detector.
Collapse
|
3
|
Godin R, Durrant JR. Dynamics of photoconversion processes: the energetic cost of lifetime gain in photosynthetic and photovoltaic systems. Chem Soc Rev 2021; 50:13372-13409. [PMID: 34786578 DOI: 10.1039/d1cs00577d] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The continued development of solar energy conversion technologies relies on an improved understanding of their limitations. In this review, we focus on a comparison of the charge carrier dynamics underlying the function of photovoltaic devices with those of both natural and artificial photosynthetic systems. The solar energy conversion efficiency is determined by the product of the rate of generation of high energy species (charges for solar cells, chemical fuels for photosynthesis) and the energy contained in these species. It is known that the underlying kinetics of the photophysical and charge transfer processes affect the production yield of high energy species. Comparatively little attention has been paid to how these kinetics are linked to the energy contained in the high energy species or the energy lost in driving the forward reactions. Here we review the operational parameters of both photovoltaic and photosynthetic systems to highlight the energy cost of extending the lifetime of charge carriers to levels that enable function. We show a strong correlation between the energy lost within the device and the necessary lifetime gain, even when considering natural photosynthesis alongside artificial systems. From consideration of experimental data across all these systems, the emprical energetic cost of each 10-fold increase in lifetime is 87 meV. This energetic cost of lifetime gain is approx. 50% greater than the 59 meV predicted from a simple kinetic model. Broadly speaking, photovoltaic devices show smaller energy losses compared to photosynthetic devices due to the smaller lifetime gains needed. This is because of faster charge extraction processes in photovoltaic devices compared to the complex multi-electron, multi-proton redox reactions that produce fuels in photosynthetic devices. The result is that in photosynthetic systems, larger energetic costs are paid to overcome unfavorable kinetic competition between the excited state lifetime and the rate of interfacial reactions. We apply this framework to leading examples of photovoltaic and photosynthetic devices to identify kinetic sources of energy loss and identify possible strategies to reduce this energy loss. The kinetic and energetic analyses undertaken are applicable to both photovoltaic and photosynthetic systems allowing for a holistic comparison of both types of solar energy conversion approaches.
Collapse
Affiliation(s)
- Robert Godin
- Department of Chemistry, The University of British Columbia, 3247 University Way, Kelowna, British Columbia, V1V 1V7, Canada. .,Clean Energy Research Center, University of British Columbia, 2360 East Mall, Vancouver, British Columbia, V6T 1Z3, Canada.,Okanagan Institute for Biodiversity, Resilience, and Ecosystem Services, University of British Columbia, Kelowna, British Columbia, Canada
| | - James R Durrant
- Department of Chemistry and Centre for Processable Electronics, Imperial College London, Exhibition Road, London SW7 2AZ, UK
| |
Collapse
|
4
|
Abstract
Transistor concepts based on semiconductor nanowires promise high performance, lower energy consumption and better integrability in various platforms in nanoscale dimensions. Concerning the intrinsic transport properties of electrons in nanowires, relatively high mobility values that approach those in bulk crystals have been obtained only in core/shell heterostructures, where electrons are spatially confined inside the core. Here, it is demonstrated that the strain in lattice-mismatched core/shell nanowires can affect the effective mass of electrons in a way that boosts their mobility to distinct levels. Specifically, electrons inside the hydrostatically tensile-strained gallium arsenide core of nanowires with a thick indium aluminium arsenide shell exhibit mobility values 30–50 % higher than in equivalent unstrained nanowires or bulk crystals, as measured at room temperature. With such an enhancement of electron mobility, strained gallium arsenide nanowires emerge as a unique means for the advancement of transistor technology. Semiconductor nanowires are promising candidates for the realization of novel transistor concepts. Here, the authors demonstrate that electron mobility in strained coaxial nanowire heterostructures can be higher than in the corresponding bulk crystals.
Collapse
|
5
|
Xu S, Huang D, Liu Z, Zhang K, Jiang H, Gou H, Zeng Z, Wang T, Su F. Hydrostatic pressure effect of photocarrier dynamics in GaAs probed by time-resolved terahertz spectroscopy. OPTICS EXPRESS 2021; 29:14058-14068. [PMID: 33985131 DOI: 10.1364/oe.421011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 04/13/2021] [Indexed: 06/12/2023]
Abstract
Pressure effects on photocarrier dynamics such as interband relaxations and intraband cooling in GaAs have been investigated using in situ time-resolved terahertz spectroscopy with a diamond anvil cell. The interband photocarrier lifetime significantly decreases by nearly two orders of magnitude as the external hydrostatic pressure is increased up to 10 GPa. Considerable pressure tuning for the intervalley scattering processes has also been observed, and the time constants under different pressures are extracted based on the three-state rate model. This work provides new perspectives on tailoring nonequilibrium carrier dynamics in semiconductors using hydrostatic pressure and may serve as the impetus for the development of high-pressure terahertz spectroscopy.
Collapse
|
6
|
Zhang Y, Li K, Zhao H. Intense terahertz radiation: generation and application. FRONTIERS OF OPTOELECTRONICS 2021; 14:4-36. [PMID: 36637780 PMCID: PMC9743905 DOI: 10.1007/s12200-020-1052-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 09/20/2020] [Indexed: 05/30/2023]
Abstract
Strong terahertz (THz) radiation provides a powerful tool to manipulate and control complex condensed matter systems. This review provides an overview of progress in the generation, detection, and applications of intense THz radiation. The tabletop intense THz sources based on Ti:sapphire laser are reviewed, including photoconductive antennas (PCAs), optical rectification sources, plasma-based THz sources, and some novel techniques for THz generations, such as topological insulators, spintronic materials, and metasurfaces. The coherent THz detection methods are summarized, and their limitations for intense THz detection are analyzed. Applications of intense THz radiation are introduced, including applications in spectroscopy detection, nonlinear effects, and switching of coherent magnons. The review is concluded with a short perspective on the generation and applications of intense THz radiation.
Collapse
Affiliation(s)
- Yan Zhang
- Department of Physics, Beijing Key Laboratory for Metamaterials and Devices, Beijing Advanced Innovation Center for Imaging Theory and Technology, Capital Normal University, Beijing, 100048, China.
| | - Kaixuan Li
- Department of Physics, Beijing Key Laboratory for Metamaterials and Devices, Beijing Advanced Innovation Center for Imaging Theory and Technology, Capital Normal University, Beijing, 100048, China
| | - Huan Zhao
- Department of Physics, Beijing Key Laboratory for Metamaterials and Devices, Beijing Advanced Innovation Center for Imaging Theory and Technology, Capital Normal University, Beijing, 100048, China
| |
Collapse
|
7
|
Bacon DR, Gill TB, Rosamond M, Burnett AD, Dunn A, Li L, Linfield EH, Davies AG, Dean P, Freeman JR. Photoconductive arrays on insulating substrates for high-field terahertz generation. OPTICS EXPRESS 2020; 28:17219-17231. [PMID: 32679934 DOI: 10.1364/oe.391656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 05/01/2020] [Indexed: 06/11/2023]
Abstract
We report on the design, fabrication and characterisation of large-area photoconductive THz array structures, consisting of a thin LT-GaAs active region transferred to an insulating substrate using a wafer-scale bonding process. The electrically insulating, transparent substrate reduces the parasitic currents in the devices, allowing peak THz-fields as high as 120 kV cm-1 to be generated over a bandwidth >5 THz. These results are achieved using lower pulse energies than demanded by conventional photoconductive arrays and other popular methods of generating high-field THz radiation. Two device sizes are fully characterised and the emission properties are compared to generation by optical rectification in ZnTe. The device can be operated in an optically saturated regime in order to suppress laser noise.
Collapse
|
8
|
Xiong L, Liu B, Liu D, Lv L, Hou Y, Shen J, Zhang B. An in situ rewritable electrically-erasable photo-memory device for terahertz waves. NANOSCALE 2020; 12:3343-3350. [PMID: 31984404 DOI: 10.1039/c9nr08826a] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
A terahertz read-only in situ electrically-erasable rewritable photo-memory device based on a perovskite:Ag (perovskite with Ag nanoparticles added)/SnO2/PEDOT:PSS hetero-junction structure is reported. Under low optical excitation, considerable terahertz amplitude modulation in a perovskite:Ag/PEDOT:PSS hybrid structure was achieved. When a SnO2 nanoparticle film was inserted between the perovskite and PEDOT:PSS layer, the attenuation of the terahertz signal was weaker than that of the perovskite:Ag/PEDOT:PSS hybrid structure; however, the SnO2 nanoparticle film considerably prolonged the recovery time of the modulated terahertz wave in air after photo-excitation was stopped. In addition, when bias voltages were applied to the perovskite:Ag/PEDOT:PSS and perovskite:Ag/SnO2/PEDOT:PSS hybrid structures, respectively, the terahertz signals recovered rapidly for both structures. Consequently, the photo-memory functionality was achieved based on a perovskite:Ag/SnO2/PEDOT:PSS hybrid structure with an in situ method for erasing stored information.
Collapse
Affiliation(s)
- Luyao Xiong
- Key Laboratory of Terahertz Optoelectronics, Ministry of Education, Beijing Advanced Innovation Center for Imaging Theory and Technology, Beijing Key Laboratory for Terahertz Spectroscopy and Imaging, Beijing Key Laboratory of Metamaterials and Devices, Department of Physics, Capital Normal University, Beijing, 100048 China.
| | - Bin Liu
- Key Laboratory of Terahertz Optoelectronics, Ministry of Education, Beijing Advanced Innovation Center for Imaging Theory and Technology, Beijing Key Laboratory for Terahertz Spectroscopy and Imaging, Beijing Key Laboratory of Metamaterials and Devices, Department of Physics, Capital Normal University, Beijing, 100048 China.
| | - Dandan Liu
- Key Laboratory of Terahertz Optoelectronics, Ministry of Education, Beijing Advanced Innovation Center for Imaging Theory and Technology, Beijing Key Laboratory for Terahertz Spectroscopy and Imaging, Beijing Key Laboratory of Metamaterials and Devices, Department of Physics, Capital Normal University, Beijing, 100048 China.
| | - Longfeng Lv
- Institution of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
| | - Yanbing Hou
- Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing Jiaotong University, Beijing, 100044, China
| | - Jingling Shen
- Key Laboratory of Terahertz Optoelectronics, Ministry of Education, Beijing Advanced Innovation Center for Imaging Theory and Technology, Beijing Key Laboratory for Terahertz Spectroscopy and Imaging, Beijing Key Laboratory of Metamaterials and Devices, Department of Physics, Capital Normal University, Beijing, 100048 China.
| | - Bo Zhang
- Key Laboratory of Terahertz Optoelectronics, Ministry of Education, Beijing Advanced Innovation Center for Imaging Theory and Technology, Beijing Key Laboratory for Terahertz Spectroscopy and Imaging, Beijing Key Laboratory of Metamaterials and Devices, Department of Physics, Capital Normal University, Beijing, 100048 China.
| |
Collapse
|
9
|
Tcypkin AN, Melnik MV, Zhukova MO, Vorontsova IO, Putilin SE, Kozlov SA, Zhang XC. High Kerr nonlinearity of water in THz spectral range. OPTICS EXPRESS 2019; 27:10419-10425. [PMID: 31052901 DOI: 10.1364/oe.27.010419] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Accepted: 03/17/2019] [Indexed: 06/09/2023]
Abstract
The values of the nonlinear refractive index coefficient for various materials in the terahertz frequency range exceed the ones in both visible and NIR ranges by several orders of magnitude. This allows to create nonlinear switches, modulators, systems requiring lower control energies in the terahertz frequency range. We report the direct measurement of the nonlinear refractive index coefficient of liquid water by using the Z-scan method with broadband pulsed THz beam. Our experimental result shows that nonlinear refractive index coefficient in water is positive and can be as large as 7×10-10 cm2/W in the THz frequency range, which exceeds the values for the visible and NIR ranges by 6 orders of magnitude. To estimate n2, we use the theoretical model that takes into account ionic vibrational contribution to the third-order susceptibility. We show that the origins of the nonlinearity observed are the anharmonicity of molecular vibrations.
Collapse
|
10
|
Li S, Nugraha PS, Su X, Chen X, Yang Q, Unferdorben M, Kovács F, Kunsági-Máté S, Liu M, Zhang X, Ouyang C, Li Y, Fülöp JA, Han J, Zhang W. Terahertz electric field modulated mode coupling in graphene-metal hybrid metamaterials. OPTICS EXPRESS 2019; 27:2317-2326. [PMID: 30732270 DOI: 10.1364/oe.27.002317] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 12/27/2018] [Indexed: 06/09/2023]
Abstract
Taking advantage of the tunable conductivity of graphene under high terahertz (THz) electric field, a graphene-metal hybrid metamaterial consisting of an array of three adjoined orthogonally oriented split-ring resonators (SRRs) is proposed and experimentally demonstrated to show a maximum modulation depth of 23% in transmission when the THz peak field reaches 305 kV/cm. The transmission of the sample is dominated by the antisymmetric and symmetric resonant modes originating from the strong magneto-inductive and conductive coupling among the three SRRs, respectively. Numerical simulations and model calculations based on a coupled oscillator theory were performed to explain the modulation process. It is found that the graphene coating impairs the resonances by increasing the damping of the modes and decreasing the coupling between the SRRs whereas the strong THz field restores the resonances by decreasing the conductivity of graphene.
Collapse
|
11
|
Shin HJ, Kim J, Kim S, Choi H, Lee S, Lee YH, Son JH, Lim SC. Unsaturated Drift Velocity of Monolayer Graphene. NANO LETTERS 2018; 18:1575-1581. [PMID: 29415543 DOI: 10.1021/acs.nanolett.7b03566] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We observe that carriers in graphene can be accelerated to the Fermi velocity without heating the lattice. At large Fermi energy | EF| > 110 meV, electrons excited by a high-power terahertz pulse ETHz relax by emitting optical phonons, resulting in heating of the graphene lattice and optical-phonon generation. This is owing to enhanced electron-phonon scattering at large Fermi energy, at which the large phase space is available for hot electrons. The emitted optical phonons cause carrier scattering, reducing the drift velocity or carrier mobility. However, for | EF| ≤ 110 meV, electron-phonon scattering rate is suppressed owing to the diminishing density of states near the Dirac point. Therefore, ETHz continues to accelerate carriers without them losing energy to optical phonons, allowing the carriers to travel at the Fermi velocity. The exotic carrier dynamics does not result from the massless nature, but the electron-optical-phonon scattering rate depends on Fermi level in the graphene. Our observations provide insight into the application of graphene for high-speed electronics without degrading carrier mobility.
Collapse
Affiliation(s)
- Hee Jun Shin
- Department of Physics , University of Seoul , Seoul 02504 , Republic of Korea
- Research Group of Food Safety , Korea Food Research Institute , Wanju 55365 , Republic of Korea
| | - Jaesu Kim
- Department of Energy Science , Sungkyunkwan University , Suwon 16419 , Republic of Korea
- IBS Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science , Sungkyunkwan University , Suwon 16419 , Republic of Korea
| | - Sungho Kim
- IBS Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science , Sungkyunkwan University , Suwon 16419 , Republic of Korea
| | - Homin Choi
- Department of Energy Science , Sungkyunkwan University , Suwon 16419 , Republic of Korea
- IBS Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science , Sungkyunkwan University , Suwon 16419 , Republic of Korea
| | - Sahnghyub Lee
- Department of Energy Science , Sungkyunkwan University , Suwon 16419 , Republic of Korea
- IBS Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science , Sungkyunkwan University , Suwon 16419 , Republic of Korea
| | - Young Hee Lee
- Department of Energy Science , Sungkyunkwan University , Suwon 16419 , Republic of Korea
- IBS Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science , Sungkyunkwan University , Suwon 16419 , Republic of Korea
- Department of Physics , Sungkyunkwan University , Suwon 16419 , Republic of Korea
| | - Joo-Hiuk Son
- Department of Physics , University of Seoul , Seoul 02504 , Republic of Korea
| | - Seong Chu Lim
- Department of Energy Science , Sungkyunkwan University , Suwon 16419 , Republic of Korea
- IBS Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science , Sungkyunkwan University , Suwon 16419 , Republic of Korea
| |
Collapse
|
12
|
Chefonov OV, Ovchinnikov AV, Romashevskiy SA, Chai X, Ozaki T, Savel'ev AB, Agranat MB, Fortov VE. Giant self-induced transparency of intense few-cycle terahertz pulses in n-doped silicon. OPTICS LETTERS 2017; 42:4889-4892. [PMID: 29216136 DOI: 10.1364/ol.42.004889] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Accepted: 10/31/2017] [Indexed: 06/07/2023]
Abstract
The results of high-field terahertz transmission experiments on n-doped silicon (carrier concentration of 8.7×1016 cm-3) are presented. We use terahertz pulses with electric field strengths up to 3.1 MV cm-1 and a pulse duration of 700 fs. A huge transmittance enhancement of ∼90 times is observed with increasing of the terahertz electric field strengths within the range of 1.5-3.1 MV cm-1.
Collapse
|
13
|
Bodrov S, Sergeev Y, Murzanev A, Stepanov A. Terahertz induced optical birefringence in polar and nonpolar liquids. J Chem Phys 2017; 147:084507. [PMID: 28863517 DOI: 10.1063/1.5000374] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The terahertz induced optical birefringence in liquids with polar (acetone, chloroform) and nonpolar (benzene, carbon tetrachloride) molecules has been investigated. Fast and slow responses were extracted from the experimental data and compared with previous studies of the femtosecond optical Kerr effect. Terahertz Kerr constants were found and compared with known DC and optical constants. Analysis of the results obtained showed that, in contrast to the optical excitation, the interaction of a permanent dipole moment of molecules with a THz field makes a significant contribution to the transient birefringence and Kerr constants. This conclusion fully agrees with the direct comparison of the femtosecond optical and THz Kerr effects reported by Sajadi et al. [Nat. Commun. 8, 14963 (2017)].
Collapse
Affiliation(s)
- Sergey Bodrov
- Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod 603950, Russia
| | - Yury Sergeev
- Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod 603950, Russia
| | - Aleksey Murzanev
- Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod 603950, Russia
| | - Andrey Stepanov
- Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod 603950, Russia
| |
Collapse
|
14
|
Miyamoto K, Kang BJ, Kim WT, Sasaki Y, Niinomi H, Suizu K, Rotermund F, Omatsu T. Highly intense monocycle terahertz vortex generation by utilizing a Tsurupica spiral phase plate. Sci Rep 2016; 6:38880. [PMID: 27966595 PMCID: PMC5155293 DOI: 10.1038/srep38880] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 11/15/2016] [Indexed: 11/28/2022] Open
Abstract
Optical vortex, possessing an annular intensity profile and an orbital angular momentum (characterized by an integer termed a topological charge) associated with a helical wavefront, has attracted great attention for diverse applications due to its unique properties. In particular for terahertz (THz) frequency range, several approaches for THz vortex generation, including molded phase plates consisting of metal slit antennas, achromatic polarization elements and binary-diffractive optical elements, have been recently proposed, however, they are typically designed for a specific frequency. Here, we demonstrate highly intense broadband monocycle vortex generation near 0.6 THz by utilizing a polymeric Tsurupica spiral phase plate in combination with tilted-pulse-front optical rectification in a prism-cut LiNbO3 crystal. A maximum peak power of 2.3 MW was obtained for THz vortex output with an expected topological charge of 1.15. Furthermore, we applied the highly intense THz vortex beam for studying unique nonlinear behaviors in bilayer graphene towards the development of nonlinear super-resolution THz microscopy and imaging system.
Collapse
Affiliation(s)
- Katsuhiko Miyamoto
- Graduate School of Advanced Integration Science, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba 263-8522, Japan.,Molecular Chirality Research Center, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - Bong Joo Kang
- Department of Physics and Department of Energy Systems Research, Ajou University, 206 Worldcup-ro, Yeongtong-gu, Suwon 16499, Korea
| | - Won Tae Kim
- Department of Physics and Department of Energy Systems Research, Ajou University, 206 Worldcup-ro, Yeongtong-gu, Suwon 16499, Korea
| | - Yuta Sasaki
- Graduate School of Advanced Integration Science, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - Hiromasa Niinomi
- Graduate School of Advanced Integration Science, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba 263-8522, Japan.,Molecular Chirality Research Center, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - Koji Suizu
- Department of Electrical, Electronics and Computer Engineering, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan
| | - Fabian Rotermund
- Department of Physics and Department of Energy Systems Research, Ajou University, 206 Worldcup-ro, Yeongtong-gu, Suwon 16499, Korea.,Department of Physics, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Korea
| | - Takashige Omatsu
- Graduate School of Advanced Integration Science, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba 263-8522, Japan.,Molecular Chirality Research Center, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| |
Collapse
|
15
|
Zhang B, He T, Shen J, Hou Y, Hu Y, Zang M, Chen T, Feng S, Teng F, Qin L. Conjugated polymer-based broadband terahertz wave modulator. OPTICS LETTERS 2014; 39:6110-6113. [PMID: 25361291 DOI: 10.1364/ol.39.006110] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
An optical broadband terahertz (THz) wave modulator, based on a polymer-inorganic interface, is investigated. The THz pulse transmission was efficiently modulated by an external continuous wave (CW) laser. The effects on the poly[2-methoxy-5-(2'-ethylhexyloxy)-1, 4-phenylenevinylene] (MEH-PPV)/silicon interface were measured by THz time-domain spectroscopy. The modulation factor reached 99.6%, at an external laser beam intensity of 6.3 W/cm2. In the proposed THz-CW system, a significant fall (in both THz transmission and reflection) was also observed at the MEH-PPV/Si interface. This reduction in THz transmission and reflection has been induced by absorption at the MEH-PPV/Si interface. The results show that an optically controlled polymer/inorganic broadband THz modulator can be realized.
Collapse
|
16
|
Joyce HJ, Parkinson P, Jiang N, Docherty CJ, Gao Q, Tan HH, Jagadish C, Herz LM, Johnston MB. Electron mobilities approaching bulk limits in "surface-free" GaAs nanowires. NANO LETTERS 2014; 14:5989-5994. [PMID: 25232659 DOI: 10.1021/nl503043p] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Achieving bulk-like charge carrier mobilities in semiconductor nanowires is a major challenge facing the development of nanowire-based electronic devices. Here we demonstrate that engineering the GaAs nanowire surface by overcoating with optimized AlGaAs shells is an effective means of obtaining exceptionally high carrier mobilities and lifetimes. We performed measurements of GaAs/AlGaAs core-shell nanowires using optical pump-terahertz probe spectroscopy: a noncontact and accurate probe of carrier transport on ultrafast time scales. The carrier lifetimes and mobilities both improved significantly with increasing AlGaAs shell thickness. Remarkably, optimized GaAs/AlGaAs core-shell nanowires exhibited electron mobilities up to 3000 cm(2) V(-1) s(-1), reaching over 65% of the electron mobility typical of high quality undoped bulk GaAs at equivalent photoexcited carrier densities. This points to the high interface quality and the very low levels of ionized impurities and lattice defects in these nanowires. The improvements in mobility were concomitant with drastic improvements in photoconductivity lifetime, reaching 1.6 ns. Comparison of photoconductivity and photoluminescence dynamics indicates that midgap GaAs surface states, and consequently surface band-bending and depletion, are effectively eliminated in these high quality heterostructures.
Collapse
Affiliation(s)
- Hannah J Joyce
- Department of Engineering, University of Cambridge , 9 JJ Thomson Avenue, Cambridge, Cambridgeshire CB3 0FA, United Kingdom
| | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Sharma G, Singh K, Ibrahim A, Al-Naib I, Morandotti R, Vidal F, Ozaki T. Self-referenced spectral domain interferometry for improved signal-to-noise measurement of terahertz radiation. OPTICS LETTERS 2013; 38:2705-2707. [PMID: 23903117 DOI: 10.1364/ol.38.002705] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
In this work, we demonstrate self-referenced spectral domain interferometry for the electro-optic sampling of terahertz (THz) electric fields. This technique allows reduction of the phase noise of the measurement, thus increasing the signal-to-noise ratio (SNR). Using the proposed technique, we achieve a more than sixfold improvement in the SNR of the detected THz electric field.
Collapse
Affiliation(s)
- Gargi Sharma
- Advanced Laser Light Source, Institut National de la Recherche Scientifique, Énergie, Matériaux et Télécommunications, Varennes, Québec, Canada
| | | | | | | | | | | | | |
Collapse
|