Phase-matching condition for THz wave generation via difference frequency generation using In<sub>x</sub>Ga<sub>1-x</sub>Se mixed crystals

Sato, Yohei; Nakajima, Mayu; Tang, Chao; Watanabe, Katsuya; Tanabe, Tadao; Oyama, Yutaka

doi:10.1364/oe.393948

Cited by 3 publications

(2 citation statements)

References 26 publications

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“…They have an extremely asymmetric layered crystal structure, which leads to relatively high second order nonlinear optical coefficients. Therefore, THz waves can be efficiently generated in GaSe and In x Ga 1-x Se crystals via DFG [57][58][59]. In birefringent materials, since the different wave vectors can be either o-or e-polarized, phase-matching can sometimes be achieved by choosing different polarization directions for collinear interactions.…”

Section: Quasi-continuous Thz Generationmentioning

confidence: 99%

Perspective on Terahertz Applications of Molecular Crystals

et al. 2022

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In this review, we present a survey on the use of molecular nonlinear crystals in the context of terahertz (THz) photonics. The fundamentals of nonlinear optics for converting optical and infrared radiation into THz radiation with the basic theory of femtosecond optical rectification and difference frequency generation are described. Various types of phase-matching conditions that can be achieved in molecular crystals are discussed. It is shown that one of the unique features of molecular crystals is the ability to generate tunable narrowband terahertz radiation using femtosecond lasers. We also provide a detailed description of the most commonly used and promising molecular crystals such as DAST, DSTMS, OH1, HMQ-TMS, DCMBI, and GUHP. This review also presents a description of recent publications which show the prospects of using molecular nonlinear optical crystals in THz photonics.

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Section: Quasi-continuous Thz Generationmentioning

confidence: 99%

Perspective on Terahertz Applications of Molecular Crystals

et al. 2022

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“…

、光化学电极 [3] 和太赫兹辐射 [4] 等新兴领域中。GaSe 晶体作为典型的 III-VI 族层状半导体 [5] ，具有高的非线性系数(d 22 =54 pm/V) ，宽的透光范围(0.62-20 µm) ，低的吸收系数(α<1 cm -1 )和大的双折射率(∆n=0.34)等优异的光学性质 [6] ，使其在 THz 辐射源 [7][8][9] 、光电探测器 [10] 、气体传感器 [11] 和高效太阳能电池 [12] 等领域具有广阔的应用前景。然而，由于弱的层间范德华力作用，本征 GaSe 晶体硬度较低，且存在大量的结构缺陷 [13] ，加剧了对太赫兹(terahertz, THz)波的吸收 [14] ，限制了其在 THz 波产生和传输中的应用。通过掺杂不仅可以增强 GaSe 晶体的机械性能，而且能够改善其结构缺陷，提高光学性质 [15] 。Shin 等人 [14] 制备了不同 Te 掺杂浓度(0.01 mass%-2.07 mass%)的 GaSe 晶体，发现 Te 掺杂 GaSe 晶体的硬度比本征 GaSe 晶体提高 25%，且 Te 掺杂 0.07 mass% GaSe 晶体利用光整流法辐射的 THz 效率比本征 GaSe 晶体增强 20%。Huang 等人 [16] 研究发现 Al 掺杂 0.13 mass% GaSe 晶体硬度是本征 GaSe 晶体的 2.6 倍，在 0.83-14 μm 范围内吸收系

…”

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Conductivity in sulfur doped gallium selenide crystals measured by terahertz time-domain spectroscopy

Li¹,

Yin²,

Huang³

et al. 2023

Acta Phys. Sin.

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In this paper, the conductivity of intrinsic GaSe, S doped 2.5 mass% GaSe, and S doped 7 mass% GaSe crystals, in the range of 0.3-2.5 THz, was measured by transmission terahertz time-domain spectroscopy, and fitted well with Drude-Smith-Lorentz model which was introduced lattice vibration effect. It was found that the real part of conductivity decreased with S doping, which was caused by the gradual shift of the Fermi energy level of GaSe crystals to the charge neutrality level due to the generation of substitution impurities and gap impurities by S doping, resulting in the reduction of carrier concentration. The intrinsic GaSe and S doping 2.5 mass% GaSe had a clear lattice vibration peak at about 0.56 THz, while GaSe: S 7% had no lattice vibration peak near 0.56 THz, which was mainly due to the S doping increased the structural hardness of the crystal and reduced the interlayer rigidity vibration of the crystal. All three samples had obvious narrow lattice vibration peaks at about 1.81 THz, and the intensity first decreased and then increased with S doping, which mainly due to a small amount of S doping reduced the local structural defects of GaSe and weakened the intensity of the narrow lattice vibration peak, while excessive S doping generated β-type GaS crystals, increased the local structural defects of the crystals and the intensity of the narrow lattice vibration peak. With the increase of S doping, the intensity of the broad lattice vibration peak of GaSe crystal weakened or even disappeared at about 1.07 THz and 2.28 THz, mainly due to the S doping resulting in S substitution impurities and GaS gap impurities, which reducing the fundamental frequency phonon vibration intensity, thereby weakening the lattice vibration caused by the second-order phonon difference mode of the crystal. The results show that the appropriate concentration of S doping can effectively suppress the lattice vibration of GaSe crystal, reduce the conductivity and power loss in the THz band. This study provides important data support and theoretical basis for the design and fabrication of low loss THz devices.

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Hybrid Dyakonov Surface Waves at Uniaxial Crystal‐Temperature‐Sensitive Material Interfaces

Sana,

Alkanhal,

Ali

et al. 2024

International Journal of Optics

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A theoretical investigation of the temperature‐dependent hybrid surface waves guided by the uniaxial crystal‐temperature‐sensitive material (TSM) interface is carried out in the present study. The uniaxial crystal is realized as a metamaterial having a direction‐dependent permittivity tensor, with the optical axis (OA) parallel to the interface. Indium antimonide (InSb) is characterized as TSM, and the temperature‐dependent electromagnetic (EM) characteristics of InSb are modeled using the extended Drude model. Analytical and numerical calculations have been performed to obtain the characteristics equation for the temperature‐dependent hybrid surface waves. The contour plot technique has been implemented in Mathematica for the computation of dispersion relation. The influence of the temperature and propagation angle on the dispersion curve, effective mode index, phase speed, and propagation length was analyzed. It is reported that the proposed interface supports the two types of surface waves (i.e., (i) pure Dyakonov surface waves (DSWs) for the temperature range (i.e., T ∈ [200, 240] K) and (ii) hybrid plasmons waves for the temperature range (i.e., T ∈ [290, 360] K)). The computed results can be used to design temperature‐assisted optical waveguides, thermo‐optical sensors, and chemical sensing/communication devices.

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Phase-matching condition for THz wave generation via difference frequency generation using In_xGa_1-xSe mixed crystals

Cited by 3 publications

References 26 publications

Perspective on Terahertz Applications of Molecular Crystals

Perspective on Terahertz Applications of Molecular Crystals

Conductivity in sulfur doped gallium selenide crystals measured by terahertz time-domain spectroscopy

Hybrid Dyakonov Surface Waves at Uniaxial Crystal‐Temperature‐Sensitive Material Interfaces

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Phase-matching condition for THz wave generation via difference frequency generation using InxGa1-xSe mixed crystals

Cited by 3 publications

References 26 publications

Perspective on Terahertz Applications of Molecular Crystals

Perspective on Terahertz Applications of Molecular Crystals

Conductivity in sulfur doped gallium selenide crystals measured by terahertz time-domain spectroscopy

Hybrid Dyakonov Surface Waves at Uniaxial Crystal‐Temperature‐Sensitive Material Interfaces

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Product

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Phase-matching condition for THz wave generation via difference frequency generation using In_xGa_1-xSe mixed crystals