AI 中文总结
该研究开发了一种全光电相干太赫兹光谱技术，采用LT-GaAs光电导体作为发射器和接收器，由Ti:Sa激光泵浦，成功实现了0.29太赫兹下硫化羰基的光谱检测，验证了其可行性并为高分辨率宽光谱太赫兹光谱仪提供了新途径。
AI 中文摘要
迄今为止，分子瞬态的相干太赫兹光谱学依赖于电子源，其带宽被限制在中心频率的一小部分。光电导器件提供了一种互补方法，结合了固有的宽带运行与相干光电产生和检测。我们报告了0.29太赫兹下硫化羰基的自由感应衰减光谱，据我们所知，这是首次同时使用脉冲发射器和相干外差接收器，二者均为LT-GaAs光电导体，由单一自由运行双频Ti:Sa激光泵浦。接收器的工作性能接近热噪声极限的15分贝，共享光学参考在超过1000次平均采集过程中保持相位相干。测得的瞬态与基于HITRAN参数的时域麦克斯韦-布洛赫模型相符。这些结果证明了全光电相干太赫兹光谱学的可行性，并确立了光电导光电混频作为一种实用途径，可用于构建在宽光谱范围内具备频率捷变、高分辨率的相干太赫兹光谱仪。
英文摘要
Coherent terahertz spectroscopy of molecular transients has so far relied on electronic sources whose bandwidth is limited to a fraction of their center frequency. Photoconductive devices offer a complementary approach, combining intrinsically broadband operation with coherent optoelectronic generation and detection. We report free-induction-decay spectroscopy of carbonyl sulfide at 0.29 THz in which, to our knowledge for the first time, both the pulsed emitter and the coherent heterodyne receiver are LT-GaAs photoconductors simultaneously pumped by a single free-running dual-frequency Ti:Sa laser. The receiver operates within 15 dB of the thermal noise limit, and the shared optical reference maintains phase coherence over more than 1000 averaged acquisitions. The measured transients agree with a time-domain Maxwell-Bloch model based on HITRAN parameters. These results demonstrate the feasibility of fully optoelectronic coherent THz spectroscopy and establish photoconductive optoelectronic mixing as a practical route toward frequency-agile, high-resolution coherent THz spectrometers over broad spectral ranges.
CommentsSubmitted to Optica. 5 pages, 4 figures, supplementary material included
