高功率窄脉冲垂直腔面发射激光器n-DBR反射率的优化

从理论上研究了n型分布布拉格反射镜(n-DBR)的反射率对器件阈值电流、输出功率以及转换效率的影响,得出了最佳反射率。在此基础上研制了垂直腔面反射激光器(VCSEL)单管和阵列器件,采用波形分析法对VCSEL器件的功率进行了测试。在脉冲宽度60ns,重复频率100Hz条件下,500μm口径单管器件在注入电流为110A时,峰值输出功率达102W,功率密度为52kW/cm2,4×4、5×5阵列器件在100A时,功率分别达到98W和103W。对比了单管器件在连续、准连续和脉冲工作条件下的输出特性和光谱特性,连续和准连续条件下激射波长的红移速率分别为0.92nm/A和0.3nm/A,6A时的内部温升分别为85℃和18℃,而脉冲条件下激射波长的红移速率仅为0.0167nm/A,6A时的温升为1.5℃,远小于连续和准连续的情况,这也是器件在脉冲条件下能得到很高输出功率的主要原因。

Optimization of n-DBR in High Power Vertical-Cavity Surface-Emitting Laser under a Short Pulsed Operation

The dependent of threshold current, output power and wall-plug efficiency on the reflectivity of n-distributed Bragg reflector (DBR) is simulated theoretically. The vertical-cavity surface-emitting laser (VCSEL) single device and arrays are fabricated and tested using waveform analysis method. The pulse width and repetition rate are 60 ns and 100 Hz, respectively. The peak output power of single device with an aperture of 500 μm is up to 102 W, corresponding to a power density of 52 kW/cm2, when the injection current is 110 A. The peak powers of 4×4 and 5×5 arrays are 98 W and 103 W at 100 A. The output power and the spectra of single device are compared at different injection currents under continuous wave (CW), quasi-CW (QCW), and pulsed operation, respectively. It is also concluded that the red shift rate of lasing wavelength is 0.92 nm/A and 0.3 nm/A, the temperature rise is 85 ℃ and 180 ℃ under CW and QCW operation, respectively. While it is only 0.0167 nm/A under pulsed operation, the corresponding temperature rise at 6 A is 1.5 ℃, which is far less than that under the other two conditions. That is why the peak power is so high under pulsed operation.