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脉冲量子级联激光器(QCL)因自热效应会导致谱线展宽,故需极短的电流脉冲驱动。理论极限线宽所需的脉宽为5~15 ns,但由于环路寄生参数的影响,窄脉冲会引起信号过冲或振荡,因此目前商用的QCL驱动器无法满足这个要求。为获得更理想的激光器线宽,在常规脉冲恒流电路的基础上,采用频率补偿的方法来消除过冲和振荡,并设计了一款稳定的纳秒级激光器驱动电路。实验结果显示该驱动装置实现了峰值电流0~2 A、脉宽8.4~200 ns、上升时间<4 ns、过冲<1%的脉冲电流输出。使用中国科学院半导体研究所研制的波长4.6μm激光器和傅里叶变换光谱仪进行测试,当驱动脉宽由100 ns减小到10 ns时,激光器线宽由0.35 cm-1线性递减到0.12 cm-1。综合验证表明,所设计的驱动装置实现了稳定的窄脉冲电流输出,尤其适用于量子级联激光器的窄线宽驱动及应用。
Pulsed Quantum Cascade Lasers (QCLs) cause spectral broadening due to self-heating effects, requiring extremely short current pulses to drive. The theoretical limit line width requires a pulse width of 5 to 15 ns, but narrow pulses can cause signal overshoot or oscillation due to loop parasitics, so commercial QCL drivers do not meet this requirement. In order to obtain a more ideal laser linewidth, based on the conventional pulse constant current circuit, the frequency compensation method is used to eliminate overshoot and oscillation, and a stable nanosecond laser driver circuit is designed. The experimental results show that the drive has a pulse current output of 0 ~ 2 A peak current, pulse width 8.4 ~ 200 ns, rise time <4 ns, and overshoot <1%. The wavelength of the laser was linearly reduced from 0.35 cm-1 to 0.12 cm-1 when the pulse width was reduced from 100 ns to 10 ns using the wavelength 4.6 μm laser and the Fourier transform spectrometer developed by Institute of Semiconductors, Chinese Academy of Sciences. . The comprehensive verification shows that the designed driving device achieves a stable narrow pulse current output, especially for the narrow linewidth driving and application of quantum cascade lasers.