GaSe crystals for broadband terahertz wave detection

Li, Kai; Xu, Jun; Zhang, Xicheng

doi:10.1063/1.1779959

Cited by 138 publications

(62 citation statements)

References 16 publications

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“…The key parameters determined from THz data using the Drude model are: the plasma frequency p = 2.6± 0.2 THz, the average momentum relaxation time ͗ ͘ = 56± 2 fs, and the mobility =89 cm 2 Gallium selenide ͑GaSe͒ is a promising semiconductor crystal for nonlinear optics and THz generation with an extremely large bandwidth up to 41 THz. 1,2 GaSe is a negative uniaxial layered semiconductor with hexagonal structure of 62 m point group with a direct band gap E g d = 2.202 eV and an indirect gap E g i = 1.995 eV at T = 300 K. The longitudinal and transverse optical phonons are located at 254 and 213 cm −1 , respectively.…”

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confidence: 99%

Terahertz studies of the dielectric response and second-order phonons in a GaSe crystal

Zeng

Kartazayev

et al. 2005

Applied Physics Letters

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The dielectric function and momentum relaxation time of carriers for a single-crystal GaSe were investigated using terahertz time-domain spectroscopy over the frequency range from 0.4to2.4THz. The key parameters determined from THz data using the Drude model are: the plasma frequency ωp=2.6±0.2THz, the average momentum relaxation time ⟨τ⟩=56±2fs, and the mobility μ=89cm2∕Vs for electrons. The THz absorption spectrum showed resonance structures attributed to the difference frequency combinations associated with acoustical and optical phonons.

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confidence: 99%

Terahertz studies of the dielectric response and second-order phonons in a GaSe crystal

Zeng

Kartazayev

et al. 2005

Applied Physics Letters

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“…The typical size of a GaSe:In sample is 7.0ϫ 5.0ϫ 0.5 mm 3 . For DLTS measurements, samples were cleaned in acetone using an ultrasonic bath.…”

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confidence: 99%

Acceptor levels in GaSe:In crystals investigated by deep-level transient spectroscopy and photoluminescence

Cui

Dupere

Bürger

et al. 2008

Journal of Applied Physics

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Deep-acceptor levels associated with indium in indium-doped GaSe crystals have been measured. High-quality Schottky diodes of GaSe:In have been fabricated and characterized using current-voltage, capacitance-voltage, and deep-level transient spectroscopy ͑DLTS͒. Four DLTS peaks at 127, 160, 248, and 319 K, corresponding to 0.21, 0.22, 0.44, and 0.74 eV above the valence band, were well resolved and assigned to be an indium-on-gallium antisite ͑In Ga ͒, a gallium vacancy ͑V Ga ͒, an indium gallium vacancy complex ͑V Ga -In͒, and a native defect associated with stacking fault or dislocation, respectively. Low-temperature photoluminescence ͑PL͒ spectroscopy measurements were performed on GaSe and GaSe:In crystals. The ground and the first excited states of the free exciton emissions were identified and the band-gap energies were determined. The results that the peak of exciton bound to acceptor ͑A 0 , X͒ disappeared and the peak of donor-acceptor pair appeared in GaSe crystal after indium doping are consistent with the DLTS acceptor assignments.

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“…Far-infrared electric transients [12,13] can be characterized by photoconductive switching [14]. Electro-optic sampling in free space [15][16][17] allows field-resolved detection at high sensitivity in the entire far-and mid-infrared spectral range [18,19]. Direct studies of the complexvalued susceptibilities of materials and the elementary dynamics in condensed matter may be performed with these methods [20,21].…”

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Paraxial Theory of Direct Electro-optic Sampling of the Quantum Vacuum

et al. 2015

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Direct detection of vacuum fluctuations and analysis of sub-cycle quantum properties of the electric field are explored by a paraxial quantum theory of ultrafast electro-optic sampling. The feasibility of such experiments is demonstrated by realistic calculations adopting a thin ZnTe electrooptic crystal and stable few-femtosecond laser pulses. We show that nonlinear mixing of a short near-infrared probe pulse with multi-terahertz vacuum field modes leads to an increase of the signal variance with respect to the shot noise level. The vacuum contribution increases significantly for appropriate length of the nonlinear crystal, short probe pulse durations, tight focusing, and sufficiently large number of photons per probe pulse. If the vacuum input is squeezed, the signal variance depends on the probe delay. Temporal positions with noise level below the pure vacuum may be traced with a sub-cycle accuracy.PACS numbers: 42.50. Ct, 42.50.Lc, 42.65.Re, 78.20.Jq Finite fluctuation amplitudes in the ground state of empty space represent the ultimate hallmark of the quantum nature of the electromagnetic radiation field. These vacuum fluctuations manifest themselves indirectly in a number of phenomena that are accessible to spectroscopy such as the spontaneous decay of excited atomic states as well as the Lamb shift [1] in atoms [2] and in quantummechanical electric circuits [3]. Access to the quantum aspects of electromagnetic radiation is provided by the analysis of photon correlation [4,5] or homodyning [6][7][8][9][10][11] measurements. However, these approaches require amplification of the quantum field under study to finite intensity and averaging of the information over multiple optical cycles.On the other side, precise determination of voltage or electric field amplitude as a function of time represents a fundamental task in science and engineering. Optical techniques have to be applied when detecting electric fields oscillating in the terahertz (THz) range and above. Those approaches involve probing with ultrashort laser pulses of a temporal duration on the order of half an oscillation period at the highest frequencies under study. Far-infrared electric transients [12,13] can be characterized by photoconductive switching [14]. Electro-optic sampling in free space [15][16][17] allows field-resolved detection at high sensitivity in the entire far-and mid-infrared spectral range [18,19]. Direct studies of the complexvalued susceptibilities of materials and the elementary dynamics in condensed matter may be performed with these methods [20,21]. The time integral of near-infrared to visible electric-field wave packets is accessible with attosecond streaking [22]. So far, all those techniques were restricted to the classical field amplitude.In this Letter, we demonstrate theoretically that the quantum properties of light may be accessed directly in the time domain, i.e. with sub-cycle temporal resolution. Our considerations are based on the realistic example of electro-optic detection with zincblende-type materials T...

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GaSe crystals for broadband terahertz wave detection

Cited by 138 publications

References 16 publications

Terahertz studies of the dielectric response and second-order phonons in a GaSe crystal

Terahertz studies of the dielectric response and second-order phonons in a GaSe crystal

Acceptor levels in GaSe:In crystals investigated by deep-level transient spectroscopy and photoluminescence

Paraxial Theory of Direct Electro-optic Sampling of the Quantum Vacuum

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