半导体激光器远轴光束的准直特性研究

Study on Collimation Properties of Semiconductor Laser off-Axis Beams

对半导体激光器光束准直场的研究具有重要的意义,半导体激光器的远轴模型能精确描述其发出的光束。根据瑞利索末菲衍射公式,利用稳相法得出了半导体激光器远轴光束经过透镜准直后的场分布解析表达式。根据该表达式可以得出如下结论:准直后光束在两个方向上的光斑大小与透镜焦距成正比,且与传输距离无关,沿轴光强与波导尺寸参量和准直透镜焦距有关,且与透镜焦距成平方反比关系,在传输距离较短的情况下,准直光场相位分布近似为球面,传输距离较长时,光场相位近似为平面.这些结论在工程应用中具有重要的价值。

The study on collimation properties of semiconductor laser beams is valuable and the off-axis model can characterize accurately the output beams of semiconductor laser, Based on Rayleigh-Sommerfeld diffraction formula, the analytical expression of the collimation field of semiconductor laser off-axis beams is derived by the method of stationary phase. According to the expression, it is found that the spot size of collimation beams in two directions is not correlative with transmission distance but proportional to the focal length of lens. On-axis intensity is inversely proportional to the square of the focal length and related to the parameters of optical waveguides. The phase distribution of collimation field is nearly spherical for a short transmission distance, while for a long transimission distance the phase distribution is close to a plane. These results are important in engineering applications.