激光成像系统中高耦合效率单模光纤耦合器设计(英文)

High coupling efficiency optical design for laser beam to single-mode fiber in lidar system

在三维激光成像系统中,其性能表现绝大部分决定于器件接收背反射光能幅度的大小,以及耦合器中空间光到光纤纤芯的光耦合效率的高低。为了增加耦合器中激光能量到纤芯内的耦合效率,提出了一种新型非球面透镜到锥形光纤头的耦合器的设计,得到了该耦合器中耦合效率的解析表达式。通过优化耦合透镜的倒相对孔径,对应波长为1 310 nm和1 550 nm的最大耦合效率分别为81.80%and 81.90%,此时的倒相对孔径分别为0.280和0.292。与通常耦合器中的耦合效率相比较,其最大耦合效率没有下降,而相应的倒相对孔径增加较大。另外,还分析了透镜-纤芯对准错位的影响,结果表明,随着对准错位的增加,耦合效率急剧下降。

In three-dimensional （3-D） imaging lidar system, the performance of the device is largely determined by the received signal magnitude of the back scattered laser energy, and the coupling efficiency of light from laser into optical fiber. In order to enhance the coupling efficiency of the light energy into fiber core, a novel design of light coupler with the aspheric lens and cone-shaped fiber head in 3-D imaging lidar system was proposed. The modification of the coupling efficiency formula was derived. By optimizing the reciprocal of relative aperture of coupling lens, the maximum coupling efficiencies of 81.80% and 81.90% in wavelength of 1 310 nm and 1 550 nm were achieved when the reciprocal of relative aperture of lens are 0.280 and 0.292 respectively. Comparing to the unrevised coupling efficiency, the revised maximum coupling efficiency does not decrease much, but the corresponding reciprocal of relative aperture increases more. In addition, the influence of the lens and fiber head on the error alignment was analyzed, and the result shows that the coupling efficiency gets down rapidly with the alignment errors increasing.