Tunability of the Free‐Spectral Range by Microwave Injection into a Mid‐Infrared Quantum Cascade Laser
Tunability of the Free‐Spectral Range by Microwave Injection into a Mid‐Infrared Quantum Cascade Laser
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DOI：
10.1002/lpor.201900389
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发表时间：
2020-04
影响因子：
11
通讯作者：
É. Rodriguez;A. Mottaghizadeh;D. Gacemi;M. Jeannin;Z. Asghari;A. Vasanelli;Y. Todorov;Qi Jie Wang;C. Sirtori
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文献类型：
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作者：
É. Rodriguez;A. Mottaghizadeh;D. Gacemi;M. Jeannin;Z. Asghari;A. Vasanelli;Y. Todorov;Qi Jie Wang;C. Sirtori
发射波长为 4.7 µm 的量子级联激光器 (QCL) 的自由光谱范围 (FSR) 可以通过直接微波调制进行调节。子带间转换固有的短载流子寿命以及阻抗匹配的电气封装允许高达 30 GHz 以上的高速调制。在频率接近往返腔的射频 (RF) 注入下，观察到激光频谱的显着展宽和平坦化。如果调制频率在器件的锁定范围内，对激光高分辨率光谱的精确分析表明，自由运行 QCL 和射频调制 QCL 均呈现梳状状态。与对微波区域中的拍音进行简单研究相比，收集高分辨率中红外光谱的主要优点之一是可以获取所有纵模，从而可以准确测量整个光谱上的 FSR。高分辨率光谱的使用可以对微波调制下的激光光谱进行深入而全面的分析。
The free‐spectral range (FSR) of quantum cascade lasers (QCLs) emitting at 4.7 µm can be tuned through direct microwave modulation. The intrinsic short carrier lifetime of inter‐subband transitions, along with impedance matched electrical packaging, allows a high‐speed modulation up to more than 30 GHz. A significant broadening and flattening of the lasing spectrum is observed under radio frequency (RF) injection with frequencies close to the round‐trip cavity. An accurate analysis of the high resolution spectra of the laser shows a comb‐like regime for both free‐running and RF modulated QCLs, if the modulation frequency is within the locking‐range of the device. One of the main advantages of collecting high‐resolution mid‐infrared spectra, over the plain investigation of the beatnote in the microwave region, is the access to all the longitudinal modes and thus the accurate measure of the FSR over the whole optical spectrum. The use of high‐resolution spectroscopy provides an in‐depth and comprehensive analysis of lasing spectra under microwave modulations.