Zhao Zhenyu, Schwagmann Andre, Ospald Frank, Driscoll Daniel C, Lu Hong, Gossard Arthur C, Smet Jurgen H
Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, 70569 Stuttgart, Germany.
Opt Express. 2010 Jul 19;18(15):15956-63. doi: 10.1364/OE.18.015956.
We experimentally study the thickness dependence of the terahertz (THz) response in {110}-oriented GaAs crystals for free space electro-optic sampling at 1.55 microm. The THz response bandwidths are analyzed and simulated under phase-matching condition with a model frequency response function. The results indicate that the detection bandwidth increases from 2 THz to 3 THz when the thickness of GaAs is reduced from 2 mm to 1 mm. Below 1 mm, the detected bandwidth is increasingly limited by the emitter characteristics and the finite probe pulse duration. The broadest bandwidth in experiment reaches 3.3 THz when using a 0.2 mm thick crystal, while it exceeds 5 THz in theory. The THz response sensitivity was studied experimentally and modeled taking into account the absorption of the THz radiation in the GaAs crystal. While absorption was found to be negligible for the crystal thickness range studied here, strong saturation is predicted theoretically for crystal thicknesses exceeding 5 mm.
我们通过实验研究了在1.55微米波长下用于自由空间电光采样的{110}取向砷化镓晶体中太赫兹（THz）响应的厚度依赖性。利用模型频率响应函数在相位匹配条件下对太赫兹响应带宽进行了分析和模拟。结果表明，当砷化镓的厚度从2毫米减小到1毫米时，检测带宽从2太赫兹增加到3太赫兹。在1毫米以下，检测带宽越来越受到发射器特性和有限探测脉冲持续时间的限制。使用0.2毫米厚的晶体时，实验中最宽的带宽达到3.3太赫兹，而理论上超过5太赫兹。通过实验研究了太赫兹响应灵敏度，并在考虑太赫兹辐射在砷化镓晶体中的吸收的情况下进行了建模。虽然在此研究的晶体厚度范围内发现吸收可忽略不计，但理论上预测对于超过5毫米的晶体厚度会有强烈的饱和现象。
