光学学报, 2021, 41 (2): 0214001, 网络出版: 2021-02-27
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 
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Terahertz Quantum Cascade Laser of First-Order Distributed Feedback Based on a Buried Grating
图 & 表
图 1. 结构示意图以及COMSOL模拟结果。(a)单金属波导掩埋光栅一级分布反馈结构示意图;(b) 掩埋光栅横截面(x-y平面)的结构示意图;(c) 单个周期内高频和低频带边模式的Ey的实部沿横截面(x-y平面)的分布;(d) 高频和低频带边模式的损耗和频率与腐蚀深度之间的关系
Fig. 1. Structure schematic and COMSOL simulation results. (a) Schematic of semi-insulated surface-plasmon buried grating first-order distributed feedback terahertz quantum cascade laser; (b) schematic of buried grating in cross section(x-y plane); (c) distribution of calculated electric field Ey of the high-frequency mode and low-frequency mode along the cross-section of laser (x-y plane); (d) impact of the etching depth on loss and the frequency of high-fr
图 2. 两个带边模式的模拟结果。(a)高频带边模式和(b)低频带边模式随着不同腐蚀深度,Ey的实部在纵向上分布的变化;(c)随着不同的腐蚀深度,高频和低频带边模式由n+ GaAs层引起的损耗
Fig. 2. Simulation results of two band-side modes. (a) High-frequency mode and (b) low-frequency mode changes in longitudinal distribution of real part of Ey with different corrosion depths; (c) high-frequency and low-frequency modes loss caused by n+ GaAs layer with different corrosion depths
图 3. Nslit=200,detch=600 nm时,低频和高频带边模式在x-y平面上|Ey|的分布。
Fig. 3. Simulated |Ey| distribution of low frequency mode and high frequency mode in the x-y plane, when Nslit=200, detch=600 nm
图 4. 模式在x-y平面上的模拟结果。(a) 高频带边模式的不同腐蚀深度掩埋光栅在有源区中心位置处的纵向基模的|Ey|2沿着激光器腔长方向上的归一化分布;(b) 当detch=400 nm, 600 nm, 800 nm, 1000 nm时,谐振腔中沿着x方向上的功率流分布
Fig. 4. Simulation results of the mode in the x-y plane. (a) Normalized distribution of |Ey|2 of longitudinal fundamental mode of buried grating at the center of active region of high-band side mode with different etching depths along the length of laser cavity; (b) power flow distribution along the x direction in the resonant cavity when detch=400 nm, 600 nm, 800 nm, and 1000 nm
图 5. 器件的SEM照片以及测试结果。(a)单金属波导掩埋光栅1st-DFB-THz-QCL的SEM照片;(b) 一个典型的掩埋光栅1st-DFB-THz-QCL的发射谱,激光器的光栅周期为12.4 μm,Nslit=200,驱动电流为2.16 A;(c) 不同的光栅周期和激光波长之间的线性关系;(d) 一个典型的单模激光器在动力学范围内不同驱动电流下的发射谱
Fig. 5. SEM pictures and test results of the devices. (a) SEM pictures of 1st-DFB-THz-QCL semi-insulated surface-plasmon buried grating; (b) emission spectrum of a typical buried grating 1st-DFB-THz-QCL, the grating period is 12.4 μm, Nslit=200, and the driving current is 2.16 A; (c) Linear relationship between different grating periods and laser wavelength; (d) emission spectrum of a typical single-mode laser under different driving currents in the dynamic range
图 6. 器件的测试结果。(a)单金属波导F-P腔激光器的电压-电流-功率特性测试结果(插图为该激光器在最大泵浦电流下的光谱); (b)掩埋光栅单模器件电压-电流-功率特性测试结果(插图为该激光器不同泵浦电流下的光谱)
Fig. 6. Test results of the devices. (a) Test results of voltage-current-power characteristics of single-metal waveguide F-P cavity laser (illustration shows the spectrum of the laser at the maximum pump current); (b) test results of voltage-current-power characteristics of buried grating single-mode devices (illustration shows the spectrum of the laser under different pump currents)
表 1计算得到的掩埋光栅结构两个带边模式在不同腐蚀深度下的光学限制因子、辐射损耗、波导损耗,辐射效率和阈值增益
Table1. Calculated optical confinement factor, radiation loss, waveguide loss, radiation efficiency, and threshold gain of the two band-edge modes of the buried grating structure at different corrosion depths
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常高垒, 朱欢, 俞辰韧, 朱海卿, 徐刚毅, 何力. 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[J]. 光学学报, 2021, 41(2): 0214001. Gaolei Chang, Huan Zhu, Chenren Yu, Haiqing Zhu, Gangyi Xu, Li He. Terahertz Quantum Cascade Laser of First-Order Distributed Feedback Based on a Buried Grating[J]. Acta Optica Sinica, 2021, 41(2): 0214001.
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