高稳定度光纤耦合半导体激光器恒流源电路设计

光纤耦合半导体激光器多用作高功率光纤激光器的泵浦源,它对电流波动十分敏感,为了确保其波长与输出功率的正常,设计了一款高稳定度恒流源电路。此恒流源电路采用闭环反馈控制,使MOS管工作在放大区来输出恒定电流,采用带有透孔的厚膜电阻作为采样电阻,其耐压高、阻值范围宽、散热能力强,大大提高了恒流源电路的稳定性,电路实现0~20 A电流可调。鉴于一般恒流源电路启闭时间较长,此电路在运放与MOS管之间加入晶体管来放大信号,缩短电路启闭时间,同时在设计中增加模拟开关电路来精确控制信号。经实验测试,此恒流源电路开启、关闭耗时较短,分别是4.5 ms与6.5 ms,恒流板结构散热能力较强且稳定,耐高温性好,电流稳定度较高,达到10-3量级,使用此电路设计的电源作为光纤耦合半导体激光器的激光电源时,激光器的中心波长与输出功率均较为稳定。

Design of constant current source circuit for high stability fiber coupled semiconductor laser

Fiber coupled semiconductor lasers are mostly used as the pump source of high-power fiber lasers,which are very sensitive to the current fluctuations.In order to ensure the normal wavelength and output power,a high stability constant current source circuit is designed.The constant current source circuit adopts closed-loop feedback control to make the MOS tube work in the amplifier area to output constant current.The thick film resistor with through-hole is used as the sampling resistor,which has high voltage resistance,wide resistance range and strong heat dissipation ability,which greatly improves the stability of the constant current source circuit and realizes the adjustable 0~20 A current.In view of the long opening and closing time of general constant-current source circuit,transistors are added between the op-amp and the MOS tube to amplify the signal and shorten the opening and closing time of the circuit.At the same time,analog switching circuit is added in the design to accurately control the signal.The experimental results show that the constant current source circuit takes 4.5 ms and 6.5 ms to turn on and off respectively.The constant current plate structure has strong and stable heat dissipation capacity,good high temperature resistance and high current stability,reaching the magnitude of 10-3,when the power supply designed by this circuit is used as the laser power supply of the fiber coupled semiconductor laser,the central wavelength and output power of the laser are relatively stable.