CPT原子钟垂直腔面发射激光器驱动电路设计

设计了一种输出电流范围在0~2 mA,用于驱动垂直腔面发射激光器(VCSEL)的恒流源电路。电路设计采用负反馈原理,可输出一个稳定的电压,该电压经过电压电流转化为恒定电流。为使输出电流更加稳定,在电路中加入现场可编程门阵列(FPGA)芯片EP4CE10F17C8组成控制电路。芯片通过采集负反馈的输出与预定值比较,得到误差量反馈到负反馈模块,调整负反馈电路的输入电压,从而使电路输出实现长期稳定。最后对电路输出性能进行测试,测试结果表明电流的纹波系数为0.01,电流稳定度为±0.02 mA。在驱动电流为1.2 mA、激光器工作温度为60℃时,用波长计测试激光器输出波长为795 nm,同时测得的吸收谱线也表明激光器输出波长在795 nm附近。因此,该恒流源电路可用于驱动VCSEL输出稳定波长。

Design of the Driving Circuit of the CPT Atomic Clock Vertical Cavity Surface Emitting Laser

A constant current source circuit with an output current range of 0-2 mA for driving a vertical cavity surface emitting laser(VCSEL) was designed. The circuit was designed based on the negative feedback principle to output a stable voltage that was converted to a constant current by the voltage and current. In order to make the output current more stable, a field programmable gate array(FPGA) chip EP4 CE10 F17 C8 was added to the circuit to form a control circuit. The output of the negative feedback was compared with a predetermined value by the chip, and the error amount fed back to the negative feedback module was obtained to adjust the input voltage of the negative feedback circuit, thereby making the circuit output stable for a long time. Finally, the circuit output performance was tested. The test results show that the current ripple coefficient is 0.01 and the current stability is ±0.02 mA. At a driving current of 1.2 mA and a laser operating temperature of 60 ℃, the output wavelength of the laser is measured by a wavelength meter to be 795 nm, and the measured absorption line also indicates that the laser output wavelength is around 795 nm. Therefore, the constant current source circuit can be used to drive the VCSEL to output a stable wavelength.