半导体激光器以体积小、质量轻、驱动功率和电流较低、效率高、工作寿命长、可直接调制、易于与各种光电子器件实现光电子集成及与半导体制造技术兼容、可大批量生产等特点得到了广泛的研究与应用，研究和改进激光器驱动电路具有重要的意义。小功率可调谐半导体激光器对驱动电流有很高的要求，驱动电流的微小变化将直接导致其输出光强的波动。为实现半导体激光器的稳定功率输出, 基于电流负反馈原理设计包含慢启动和限流保护电路的恒流驱动电路。在电路设计中尽可能利用简单的器件和设计起到改善激光器正常工作的目的。在调制过程中分别利用运放与三极管的不同特性设计出了低频低失真和高频开关调制电路。利用两级放大负反馈原理进行反馈电流的调整，降低闭环带宽，增强了闭环负反馈的稳定性。

Semiconductor laser is widely researched and applied with the characteristics of small size, light weight, low drive power and current, high efficiency, long operation life, being directly modulated, easy to be integrated with optoelectronic devices, being compatible with semiconductor fabrication technologies and mass-produced. Researching and improving laser driving circuits have great significance. Small power tunable semiconductor laser has particularly high requirements on driving current, small changes in the driving current will directly lead to the fluctuations of output light intensity. In order to achieve a stable output power for semiconductor laser, a constant current driving circuit containing slow start and current limit protection circuits is designed based on current negative feedback principle. In the circuit design, simple devices and design are used as possible to improve the normal operation of lasers. In modulation process, low-frequency distortion and high-frequency switching modulation circuits are designed based on the different characteristics of amplifiers and triode respectively. The feedback current is modulated based on the principle of two amplification negative feedback. The bandwidth of closed-loop is lowed and the stability of closed-loop negative feedback is enhanced.