基于掩埋光栅一级分布反馈结构的太赫兹量子级联激光器

Terahertz Quantum Cascade Laser of First-Order Distributed Feedback Based on a Buried Grating

结合理论和实验研究了掩埋光栅一级分布反馈太赫兹量子级联激光器中的模式竞争和功率特性。理论计算得到掩埋光栅腐蚀深度与两个带边模式的波导损耗、光学限制因子、辐射损耗以及辐射效率的关系。理论计算表明,掩埋光栅分布反馈结构可以通过改变腐蚀深度,保证激光器稳定单模工作在高频带边模式的同时,调节激光器的阈值增益以及辐射效率。实验和测试结果表明,激光器辐射波长和掩埋光栅的周期成正比,激光器可以在整个动力学范围内稳定单模工作。单模激光器的波长范围可覆盖86.2~91.7μm的范围,边模抑制比可达25 dB,最大输出功率为9.1 mW。该工作有助于高性能单模太赫兹激光器及锁相耦合激光器阵列的研制。

We experimentally and theoretically investigated the mode competition and output power characteristics in the terahertz quantum cascade lasers of first-order distributed feedback based on a buried grating.The simulations obtained the relationships of the etching depth of a buried grating with the waveguide loss,optical confinement factor,radiation loss,and radiation efficiency of two band-edge modes.Theoretical calculations have obtained the relationship between buried grating corrosion depth and waveguide loss,optical confinement factor,radiation loss,and radiation efficiency of the two band-edge modes.Theoretical calculations show that the distributed feedback structure of the buried grating can adjust the threshold gain and radiation efficiency of the laser while ensuring the stable single-mode operation of the laser in the high-band side mode by changing the corrosion depth.Experimental and test results show that the laser radiation wavelength is proportional to the period of the buried grating and the laser could operate stably in a single mode in the whole dynamic range.The single-mode laser can cover the range from 86.2μm to 91.7μm,the side mode rejection ratio can reach 25 dB,and the maximum output power is 9.1 mW.This work is helpful for the development of high-performance single-mode terahertz lasers and phase-locked laser arrays.