4×25Gbit/s并行光模块杂散光抑制结构设计

Design of stray light suppression structure for 4×25Gbit/s parallel optical module

4×25Gbit/s并行光模块内部杂散光会导致能量损耗、鬼像及光串扰,进而降低通信质量。分析垂直腔面发射激光器光束特性,根据高斯光束传输特性理论,结合光阑孔径边缘菲涅尔衍射效应,提出锥形遮光罩结构设计方案。利用能量传输定理,在ZEMAX非序列模式下完成遮光罩与光阑建模,进行鬼像分析并对优化后的系统光束进行光线追迹。结果表明,优化后二次鬼像数量减少了75个,杂散光数量相比于优化前下降49%,其中影响最大的鬼像能量由4.03×10（-4）lx降至3.23×10（-5）lx,杂散光能量下降一个数量级以上。光束在光纤接受端面的能量相比光源输入的能量衰减了15%左右。这一结果对解决光网络杂散光的影响具有一定的参考价值。

The stray light causes energy loss,ghost images and optical crosstalk in 4 × 25 Gbit/s parallel optical module,thereby reducing the communication quality. The beam characteristics of VCSEL are analyzed. According to Gaussian beam transmission theory,the conical structure scheme of the lens hood is proposed based on Fresnel diffraction effect of the aperture diaphragm. The lens hood and aperture models can be built by the energy transfer theorem in ZEMAX non-sequential mode. Ghost images analysis and ray tracing are carried out on the optimized system. The results show that the number of ghost images decreased by 75 after optimization,and the amount of stray light is 49%lower than that before optimization. Among them,the biggest ghost energy drop from 4. 03×10^（-4） lx to 3. 23×10^（-5） lx. It is attenuated by about 15% compared to the energy input by the light source that the energy at the receiving end of the optical fiber. This result has a certain reference value to solve the stray light influence of optical network.