We report on optical rectification in a $⟨110⟩$ ${\mathrm{AgGaSe}}_2$ crystal that produces terahertz (THz) electric field pulses across the broad frequency range of 0.02–4 THz. Due to the large coherence length of the ${\mathrm{AgGaSe}}_2$ crystal ($>4$ times larger than that of ${\mathrm{CdSiP}}_2$ and ${\mathrm{ZnGeP}}_2$), in-phase THz radiation is produced over the entire crystal thickness of 485 μm. Furthermore, THz time-domain spectroscopy is used to determine the ordinary and extraordinary refractive indices and extinction coefficients of the uniaxial ${\mathrm{AgGaSe}}_2$ crystal across the broad spectral range of 0.5–2.9 THz, encompassing several phonon resonances.

中文翻译：

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黄铜矿AgGaSe ₂晶体中的光学整流，用于产生宽带太赫兹辐射

我们在 $⟨110⟩$ ${\mathrm{砷化镓硒}}_{\mathrm{2个}}$晶体会在0.02–4 THz的宽频率范围内产生太赫兹（THz）电场脉冲。由于相干长度大${\mathrm{砷化镓硒}}_{\mathrm{2个}}$ 水晶 （$>4$ 倍于 ${\mathrm{镉硅}}_{\mathrm{2个}}$ 和 ${\mathrm{锌锗磷}}_{\mathrm{2个}}$），在485μm的整个晶体厚度上都会产生同相THz辐射。此外，太赫兹时域光谱用于确定单轴的寻常和非寻常折射率以及消光系数${\mathrm{砷化镓硒}}_{\mathrm{2个}}$ 晶体在0.5–2.9 THz的宽光谱范围内，包含多个声子共振。