光子带隙光纤准直器回波损耗研究

研究了一种光子带隙光纤准直器。为了降低回波对光源的干扰，通常光纤准直器的回波损耗不应低于60 dB。由于带隙光纤端面没有反射，因此满足这一条件的带隙光纤准直器GRIN透镜入射面的倾斜角与普通光纤准直器不同。从高斯光束通过光学系统的一般模型出发，利用矩阵光学和高斯光束耦合理论，推导了光线传输矩阵。结合实际应用中光纤及GRIN透镜的参数，仿真分析了尾纤与GRIN透镜之间的间距及GRIN透镜的参数对准直器回波损耗的影响。结果表明，镀有增透膜时，当光子带隙光纤准直器的GRIN透镜入射面倾角等于3时，回波损耗大于60 dB。研究结果对进行光子带隙光纤准直器的设计具有指导意义。

Return loss of photonic bandgap fibers collimator

A photonic bandgap fiber collimator was proposed. To reduce the interference of light power from the echo, the return loss of fiber collimator should exceed 60 dB. There was no reflection in photonic bandgap fiber end face, thus the beveled angle of GRIN lens of photonic bandgap fiber collimator and ordinary fiber collimator satisfied the criterion were different. Based on the theory of matrix optics and Gaussian-beam coupling, the transform matrix was deduced from the general model of Gaussian-beam through a complex optical system. With the practical parameters of photonic bandgap fiber and GRIN lens, the influence of the distance between fiber tail and GRIN lens and the influence of the parameter of the GRIN lens on return-loss were both stimulated and analyzed. The results show that the return loss exceed 60 dB when the beveled angle of GRIN lens was 3. The results may direct the design of PBF collimator.