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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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Peters L, Tunesi J, Pasquazi A, Peccianti M. Optical Pump Rectification Emission: Route to Terahertz Free-Standing Surface Potential Diagnostics. Sci Rep 2017; 7:9805. [PMID: 28851895 PMCID: PMC5575250 DOI: 10.1038/s41598-017-08734-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 07/07/2017] [Indexed: 11/18/2022] Open
Abstract
We introduce a method for diagnosing the electric surface potential of a semiconductor based on THz surface generation. In our scheme, that we name Optical Pump Rectification Emission, a THz field is generated directly on the surface via surface optical rectification of an ultrashort pulse after which the DC surface potential is screened with a second optical pump pulse. As the THz generation directly relates to the surface potential arising from the surface states, we can then observe the temporal dynamics of the static surface field induced by the screening effect of the photo-carriers. Such an approach is potentially insensitive to bulk carrier dynamics and does not require special illumination geometries.
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Affiliation(s)
- L Peters
- Emergent Photonics Lab (EPic), Dept. of Physics and Astronomy, University of Sussex, Brighton, BN1 9QH, UK
| | - J Tunesi
- Emergent Photonics Lab (EPic), Dept. of Physics and Astronomy, University of Sussex, Brighton, BN1 9QH, UK
| | - A Pasquazi
- Emergent Photonics Lab (EPic), Dept. of Physics and Astronomy, University of Sussex, Brighton, BN1 9QH, UK
| | - M Peccianti
- Emergent Photonics Lab (EPic), Dept. of Physics and Astronomy, University of Sussex, Brighton, BN1 9QH, UK.
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Elsaesser T, Reimann K, Woerner M. Focus: Phase-resolved nonlinear terahertz spectroscopy--From charge dynamics in solids to molecular excitations in liquids. J Chem Phys 2015; 142:212301. [PMID: 26049419 DOI: 10.1063/1.4916522] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Intense terahertz (THz) electric field transients with amplitudes up to several megavolts/centimeter and novel multidimensional techniques are the key ingredients of nonlinear THz spectroscopy, a new area of basic research. Both nonlinear light-matter interactions including the non-perturbative regime and THz driven charge transport give new insight into the character and dynamics of low-energy excitations of condensed matter and into quantum kinetic phenomena. This article provides an overview of recent progress in this field, combining an account of technological developments with selected prototype results for liquids and solids. The potential of nonlinear THz methods for future studies of low-frequency excitations of condensed-phase molecular systems is discussed as well.
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Affiliation(s)
- Thomas Elsaesser
- Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, 12489 Berlin, Germany
| | - Klaus Reimann
- Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, 12489 Berlin, Germany
| | - Michael Woerner
- Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, 12489 Berlin, Germany
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Teo SM, Ofori-Okai BK, Werley CA, Nelson KA. Invited Article: Single-shot THz detection techniques optimized for multidimensional THz spectroscopy. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2015; 86:051301. [PMID: 26026507 DOI: 10.1063/1.4921389] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Multidimensional spectroscopy at visible and infrared frequencies has opened a window into the transfer of energy and quantum coherences at ultrafast time scales. For these measurements to be performed in a manageable amount of time, one spectral axis is typically recorded in a single laser shot. An analogous rapid-scanning capability for THz measurements will unlock the multidimensional toolkit in this frequency range. Here, we first review the merits of existing single-shot THz schemes and discuss their potential in multidimensional THz spectroscopy. We then introduce improved experimental designs and noise suppression techniques for the two most promising methods: frequency-to-time encoding with linear spectral interferometry and angle-to-time encoding with dual echelons. Both methods, each using electro-optic detection in the linear regime, were able to reproduce the THz temporal waveform acquired with a traditional scanning delay line. Although spectral interferometry had mediocre performance in terms of signal-to-noise, the dual echelon method was easily implemented and achieved the same level of signal-to-noise as the scanning delay line in only 4.5% of the laser pulses otherwise required (or 22 times faster). This reduction in acquisition time will compress day-long scans to hours and hence provides a practical technique for multidimensional THz measurements.
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Affiliation(s)
- Stephanie M Teo
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Benjamin K Ofori-Okai
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Christopher A Werley
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Keith A Nelson
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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Arik E, Altan H, Esenturk O. Dielectric properties of ethanol and gasoline mixtures by terahertz spectroscopy and an effective method for determination of ethanol content of gasoline. J Phys Chem A 2014; 118:3081-9. [PMID: 24701997 DOI: 10.1021/jp500760t] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Investigation of frequency dependent permittivity of mixture solutions provides information on the role of intermolecular interactions on relaxation processes of solvent and solute molecules. In this study the dielectric properties of ethanol/gasoline mixtures in the terahertz spectral region are investigated. Frequency dependent absorption coefficients, refractive indices, and complex permittivities of pure ethanol and gasoline, and their mixtures at varying ethanol volume percentages (v/v %) are reported. As the mixing ratio changes, meaningful shifts are observed in the frequency dependent refractive index and absorption coefficients associated with the dominant component, ethanol. The relaxation dynamics of the pure gasoline and ethanol are successfully modeled with the Debye model using the ultrafast nature of the terahertz transients, and those of mixture solutions are investigated by an additive model with an assumption of minimum interaction due to the significant differences in their molecular natures; polar and nonpolar. Successful modeling of the mixtures confirms the weak interaction assumption and enables us to accurately determine the ethanol content. Among five ethanol/gasoline blends, except for one mixture, the estimated percent ethanol in gasoline is predicted with an accuracy of ca. 1% with respect to the actual ethanol percentage. In addition, the results show that free OH contribution to the macroscopic polarization is significantly higher at low concentrations (5-20%) and lower at 50% compared to the case of pure ethanol. The measurements and analysis presented here show that time domain terahertz studies can offer invaluable insight into development of new models for polar/nonpolar complex mixture solutions.
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Affiliation(s)
- Enis Arik
- Department of Chemistry, Middle East Technical University , Ankara 06800, Turkey
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Abstract
Terahertz (THz) radiation occupies part of the electromagnetic spectrum between the infrared and microwave bands. Until recently, technology at THz frequencies was under-developed compared to the rest of the electromagnetic spectrum, leaving a gap between millimeter waves and the far-infrared (FIR). In the past decade, interest in the THz gap has been increased by the development of ultrafast laser-based T-ray systems and their demonstration of diffraction-limited spatial resolution, picosecond temporal resolution, DC-THz spectral bandwidth and signal-to-noise ratios above 104. This chapter reviews the development, the state of the art and the applications of T-ray spectrometers. Continuous-wave (CW) THz-frequency sources and detectors are briefly introduced in comparison to ultrafast pulsed THz systems. An emphasis is placed on experimental applications of T-rays to sensing and imaging, with a view to the continuing advance of technologies and applications in the THz band.
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Affiliation(s)
- S. P. Mickan
- Department of Physics, Applied Physics & Astronomy, and Department of Electrical, Computer & System Engineering, Rensselaer Polytechnic Institute, Troy NY 12180, USA
| | - X.-C. Zhang
- Department of Physics, Applied Physics & Astronomy, and Department of Electrical, Computer & System Engineering, Rensselaer Polytechnic Institute, Troy NY 12180, USA
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Zhang W, Azad AK, Han J, Xu J, Chen J, Zhang XC. Direct observation of a transition of a surface plasmon resonance from a photonic crystal effect. PHYSICAL REVIEW LETTERS 2007; 98:183901. [PMID: 17501575 DOI: 10.1103/physrevlett.98.183901] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2006] [Indexed: 05/15/2023]
Abstract
Transition of surface-plasmon resonance from out-of-plane photonic crystal effect is observed in a semiconductor array of subwavelength holes by optical pump-terahertz probe measurements. The dielectric properties of the photoexcited array are essentially altered by the intense optical excitation due to photogenerated free carriers. As a result, the array becomes metallic and favors the coupling and propagation of surface plasmons. The photoinduced resonant extremes agree well with the Fano model.
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Affiliation(s)
- Weili Zhang
- School of Electrical and Computer Engineering, Oklahoma State University, Stillwater, Oklahoma 74078, USA
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Brown MS, Fiechtner GJ, Rudd JV, Zimdars DA, Warmuth M, Gord JR. Water-vapor detection using asynchronous THz sampling. APPLIED SPECTROSCOPY 2006; 60:261-5. [PMID: 16608568 DOI: 10.1366/000370206776342670] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The use of a fiber-coupled terahertz (THz) transmitter/receiver pair for spectroscopic detection of water vapor is investigated. Transmission signals of an alumina cylinder demonstrate that the measurement approach can be applied in a windowless ceramic combustor. First, a conventional commercial transmitter/receiver pair is used to make measurements for frequencies to 1.25 THz. Water-vapor absorption is clearly evident within the alumina transparency window and is readily modeled using existing databases. A variety of data-acquisition schemes is possible using THz instrumentation. To assess signal-collection techniques, a prototype THz transmitter/receiver pair is then used with the asynchronous optical-sampling (ASOPS) technique to obtain asynchronous THz-sampling signals to 1 THz without the need for an optomechanical delay line. Two mode-locked Ti:sapphire lasers operating at slightly different repetition rates are used for pumping the transmitter and receiver independently to permit a complete time-domain THz signal to be recorded. The resulting repetitive phase walkout is demonstrated by collecting power spectra of room air that exhibit water-vapor absorption.
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Affiliation(s)
- Michael S Brown
- Innovative Scientific Solutions, Inc., 2766 Indian Ripple Road, Dayton, Ohio 45440-3638, USA.
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Janke C, Rivas JG, Bolivar PH, Kurz H. All-optical switching of the transmission of electromagnetic radiation through subwavelength apertures. OPTICS LETTERS 2005; 30:2357-9. [PMID: 16196318 DOI: 10.1364/ol.30.002357] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Unprecedented optical control of the surface plasmon polariton assisted transmission of terahertz radiation through subwavelength apertures is rendered possible by carrier-induced changes to the dielectric properties of a semiconductor grating. Although the study presented is static, the extension of our approach to dynamic switching and tuning is deemed straightforward, opening the way for the realization of ultrafast surface plasmon based devices.
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Affiliation(s)
- C Janke
- Institut für Halbleitertechnik, RWTH Aachen University, D-52056 Aachen, Germany
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Nĕmec H, Kadlec F, Surendran S, Kuzel P, Jungwirth P. Ultrafast far-infrared dynamics probed by terahertz pulses: A frequency domain approach. I. Model systems. J Chem Phys 2005; 122:104503. [PMID: 15836328 DOI: 10.1063/1.1857851] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Time-resolved terahertz spectroscopy has become a widely used experimental tool for the investigation of ultrafast dynamics of polar systems in the far infrared. We have recently proposed an analytical method for the extraction of a transient two-dimensional susceptibility from the experimental data [Nĕmec, Kadlec, and Kuzel, J. Chem. Phys. 117, 8454 (2002)]. In the present paper the methodology of optical pump-terahertz probe experiments is further developed for direct application in realistic experimental situations. The expected two-dimensional transient response function is calculated for a number of model cases (including Drude dynamics of free carriers, harmonic and anharmonic oscillator modes); these results serve as a basis for the interpretation of experimental results. We discuss also the cases where only partial (one-dimensional) information about the system dynamics can be experimentally obtained.
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Affiliation(s)
- H Nĕmec
- Institute of Physics, Academy of Sciences of the Czech Republic, and Center for Complex Molecular Systems and Biomolecules, Na Slovance 2, 182 21 Prague 8, Czech Republic
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Affiliation(s)
- Charles A Schmuttenmaer
- Department of Chemistry, Yale University, 225 Prospect Street, P.O. Box 208107, New Haven, Connecticut 06520-8107, USA
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Knoesel E, Bonn M, Shan J, Wang F, Heinz TF. Conductivity of solvated electrons in hexane investigated with terahertz time-domain spectroscopy. J Chem Phys 2004; 121:394-404. [PMID: 15260559 DOI: 10.1063/1.1757442] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present investigations of the transient photoconductivity and recombination dynamics of quasifree electrons in liquid n-hexane and cyclohexane performed using terahertz time-domain spectroscopy (THz-TDS). Quasifree electrons are generated by two-photon photoionization of the liquid using a femtosecond ultraviolet pulse, and the resulting changes in the complex conductivity are probed by a THz electromagnetic pulse at a variable delay. The detection of time-domain wave forms of the THz electric field permits the direct determination of both the real and the imaginary part of the conductivity of the electrons over a wide frequency range. The change in conductivity can be described by the Drude model, thus yielding the quasifree electron density and scattering time. The electron density is found to decay on a time scale of a few hundred picoseconds, which becomes shorter with increasing excitation density. The dynamics can be described by a model that assumes nongeminate recombination between electrons and positive ions. In addition, a strong dependence of the quasifree electron density on temperature is observed, in agreement with a two-state model in which the electron may exist in either a quasifree or a bound state.
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Affiliation(s)
- Ernst Knoesel
- Department of Physics and Astronomy, Rowan University, Glassboro, New Jersey 08028, USA.
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Němec H, Kadlec F, Kužel P. Methodology of an optical pump-terahertz probe experiment: An analytical frequency-domain approach. J Chem Phys 2002. [DOI: 10.1063/1.1512648] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Knoesel E, Bonn M, Shan J, Heinz TF. Charge transport and carrier dynamics in liquids probed by THz time-domain spectroscopy. PHYSICAL REVIEW LETTERS 2001; 86:340-343. [PMID: 11177826 DOI: 10.1103/physrevlett.86.340] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2000] [Indexed: 05/23/2023]
Abstract
We examine the transport properties and the dynamics of free electrons in n-hexane by means of femtosecond spectroscopy using an ultraviolet pump pulse to create the electrons and a THz electromagnetic pulse as a probe. The complex dielectric response of the photogenerated electrons is determined over a broad range of frequencies, from which we infer the electron scattering time and density through the Drude model. The time evolution of the carrier density reveals nongeminate electron-ion recombination within hundreds of picoseconds at high ion concentration.
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Affiliation(s)
- E Knoesel
- Department of Physics, Columbia University, New York, New York 10027, USA
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Ohtake H, Ono S, Sakai M, Kawahata E, Kozeki T, Murakami H, Liu Z, Tsukamoto T, Sarukura N. Development of Intense and Compact THz-Radiation Source Using Femtosecond-Laser Irradiated InAs Emitter in a High Magnetic Field. J CHIN CHEM SOC-TAIP 2000. [DOI: 10.1002/jccs.200000083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Kindt JT, Schmuttenmaer CA. Theory for determination of the low-frequency time-dependent response function in liquids using time-resolved terahertz pulse spectroscopy. J Chem Phys 1999. [DOI: 10.1063/1.478766] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Kindt JT, Schmuttenmaer CA. Far-Infrared Dielectric Properties of Polar Liquids Probed by Femtosecond Terahertz Pulse Spectroscopy. ACTA ACUST UNITED AC 1996. [DOI: 10.1021/jp960141g] [Citation(s) in RCA: 526] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- J. T. Kindt
- Department of Chemistry, Yale University, 225 Prospect St., New Haven, Connecticut 06520-8107
| | - C. A. Schmuttenmaer
- Department of Chemistry, Yale University, 225 Prospect St., New Haven, Connecticut 06520-8107
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Tielking NE, Bensky TJ, Jones RR. Effects of imperfect unipolarity on the ionization of Rydberg atoms by subpicosecond half-cycle pulses. PHYSICAL REVIEW. A, ATOMIC, MOLECULAR, AND OPTICAL PHYSICS 1995; 51:3370-3373. [PMID: 9911982 DOI: 10.1103/physreva.51.3370] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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Benicewicz PK, Taylor AJ. Scaling of terahertz radiation from large-aperture biased InP photoconductors. OPTICS LETTERS 1993; 18:1332. [PMID: 19823373 DOI: 10.1364/ol.18.001332] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
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You D, Jones RR, Bucksbaum PH, Dykaar DR. Generation of high-power sub-single-cycle 500-fs electromagnetic pulses. OPTICS LETTERS 1993; 18:290. [PMID: 19802113 DOI: 10.1364/ol.18.000290] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
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Federici JF, Greene BI, Saeta PN, Dykaar DR, Sharifi F, Dynes RC. Direct picosecond measurement of photoinduced Cooper-pair breaking in lead. PHYSICAL REVIEW. B, CONDENSED MATTER 1992; 46:11153-11156. [PMID: 10002986 DOI: 10.1103/physrevb.46.11153] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Chuang SL, Schmitt-Rink S, Greene BI, Saeta PN, Levi AF. Optical rectification at semiconductor surfaces. PHYSICAL REVIEW LETTERS 1992; 68:102-105. [PMID: 10045123 DOI: 10.1103/physrevlett.68.102] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Froberg N, Bin Bin Hu, Xi-Cheng Zhang, Auston D. Terahertz radiation from a photoconducting antenna array. IEEE JOURNAL OF QUANTUM ELECTRONICS 1992; 28:2291-2301. [DOI: 10.1109/3.159536] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
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