Li Yuanyuan, Yang Ning, Xie Yan, Chu Weidong, Zhang Wei, Duan Suqing, Wang Jian
Opt Express. 2019 Feb 4;27(3):3146-3160. doi: 10.1364/OE.27.003146.
The phase-locking, noise, and modulation properties of two face-to-face optically mutual-injected terahertz (THz) quantum cascade lasers (QCLs) are analyzed theoretically. In the phase-locking range, the two THz QCLs are in stationary states working at the same frequency. Outside the phase-locking range, the amplitude and the instantaneous frequency of the optical field oscillate with time, and the power spectrum shows a series of discrete peaks. For strong mutual injection, the optical field of the THz QCL array also exhibits oscillatory behavior. Coherent collapse or chaotic behavior is not observed within the range of the parameters used in this simulation. The spontaneous emission noise of phase-locked THz QCLs is higher than that of THz QCLs at free-running operation, and mutual injection may introduce additional modulation peaks in the noise spectrum. The modulation response of the mutual-injected THz QCLs to an individual modulation is investigated. It is found that the modulation bandwidth and the phase difference are significantly dependent on the modulation parameters. These results are helpful for further understanding the nonlinear dynamic behaviors of THz QCLs under optical injection and provide theoretical support for the development of THz QCL phase-locked arrays.
从理论上分析了两个面对面光互注入太赫兹（THz）量子级联激光器（QCL）的锁相、噪声和调制特性。在锁相范围内，两个太赫兹QCL处于以相同频率工作的稳态。在锁相范围之外，光场的幅度和瞬时频率随时间振荡，功率谱显示出一系列离散峰。对于强互注入，太赫兹QCL阵列的光场也表现出振荡行为。在本模拟所使用的参数范围内未观察到相干崩溃或混沌行为。锁相太赫兹QCL的自发辐射噪声高于自由运行的太赫兹QCL，互注入可能会在噪声谱中引入额外的调制峰。研究了互注入太赫兹QCL对单个调制的调制响应。发现调制带宽和相位差显著依赖于调制参数。这些结果有助于进一步理解光注入下太赫兹QCL的非线性动力学行为，并为太赫兹QCL锁相阵列的发展提供理论支持。
