Engineering the spectral bandwidth of quantum cascade laser frequency combs
Engineering the spectral bandwidth of quantum cascade laser frequency combs
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DOI：
10.1364/ol.424164
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发表时间：
2021-07-15
期刊：
影响因子：
3.6
通讯作者：
Schwarz, Benedikt
中科院分区：
文献类型：
--
作者：
Beiser, Maximilian;Opacak, Nikola;Schwarz, Benedikt
量子级联激光器（QCL）促进了在中红外和太赫兹光谱区域中操作的紧凑的光学频率梳源，其中许多分子具有其基本吸收线。提高这些芯片大小的激光器的光学带宽对于解决其在宽带高精度光谱中的应用至关重要。在这项工作中，我们提供了一个数值和实验研究的梳状光谱宽度，并显示如何可以优化，以获得其最大值定义的激光增益带宽。共振克尔非线性和腔色散的非最佳值的相互作用可以导致梳状谱的显着变窄，并揭示了色散补偿的最佳方法。高镜损耗的实施被证明是有利的，并在扩散的梳状边模的结果。最后，通过在往返频率附近调制激光偏置的QCL的注入锁定提供了稳定的外部旋钮来控制调频梳状状态并恢复解锁激光状态的最大光谱宽度。由The Optical Society根据知识共享署名4.0许可证条款发布。
Quantum cascade lasers (QCLs) facilitate compact optical frequency comb sources that operate in the mid-infrared and terahertz spectral regions, where many molecules have their fundamental absorption lines. Enhancing the optical bandwidth of these chip-sized lasers is of paramount importance to address their application in broadband high-precision spectroscopy. In this work, we provide a numerical and experimental investigation of the comb spectral width and show how it can be optimized to obtain its maximum value defined by the laser gain bandwidth. The interplay of nonoptimal values of the resonant Kerr nonlinearity and cavity dispersion can lead to significant narrowing of the comb spectrum and reveals the best approach for dispersion compensation. The implementation of high mirror losses is shown to be favorable and results in proliferation of the comb sidemodes. Ultimately, injection locking of QCLs by modulating the laser bias around the round trip frequency provides a stable external knob to control the frequencymodulated comb state and recover the maximum spectral width of the unlocked laser state. Published by The Optical Society under the terms of the Creative Commons Attribution 4.0 License.