Laser Diode to Single-Mode Circular Core Dispersion Compensation Fiber Coupling with Cylindrical Microlens on the Fiber Tip: Influence of Misalignment on Coupling Efficiency

This paper reports a theoretical investigation of a coupler involving a laser diode (LD) and a mono-mode circular core dispersion-shifted (DS) and dispersion-flattened (DF) fibers with a cylindrical microlens (CML) on its tip. The study takes into account potential angular and transverse mismatches. The research focuses on analyzing coupling efficiencies considering specific types of misalignments by employing a relevant ABCD refraction matrix for the CML in the vertical plane, as the horizontal plane coupling performance is deemed poor. The analysis uses Gaussian field distribution based on two common wavelengths, 1.3 µm and 1.5 µm. The formulations presented require relatively low computation effort. The study highlights the degree of sensitivity of the coupler's performance when the mentioned types of offsets are present. The outcomes of the research are expected to be valuable for manufacturers who are involved in the development of devices incorporating CMLs, particularly in the fields of lasers and fibers.