Opt Express. 2023 Apr 24;31(9):13888-13894. doi: 10.1364/OE.483883.
We demonstrate the frequency stabilization of a terahertz quantum-cascade laser (QCL) to the Lamb dip of the absorption line of a DO rotational transition at 3.3809309 THz. To assess the quality of the frequency stabilization, a Schottky diode harmonic mixer is used to generate a downconverted QCL signal by mixing the laser emission with a multiplied microwave reference signal. This downconverted signal is directly measured by a spectrum analyzer showing a full width at half maximum of 350 kHz, which is eventually limited by high-frequency noise beyond the bandwidth of the stabilization loop.
我们将太赫兹量子级联激光器（QCL）的频率稳定到 3.3809309 THz 处 DO 转动跃迁吸收线的兰姆凹陷。为了评估频率稳定的质量，肖特基二极管谐波混频器用于通过将激光发射与倍频微波参考信号混合来产生下变频 QCL 信号。该下变频信号直接由频谱分析仪测量，显示出 350 kHz 的半最大值全宽，最终受到稳定环路带宽之外的高频噪声的限制。
