Misalignment considerations in a laser diode to monomode elliptic core fiber coupling via a hyperbolic microlens on the fiber tip: efficiency computation by the ABCD matrix

Abstract

We report the theoretical investigation of the coupling optics involving a laser diode and an elliptic-core single-mode step index fiber with a hyperbolic microlens on the tip of the fiber in the presence of possible transverse and angular mismatches. By employing Gaussian field distributions for both the source and the fiber, and also the prescribed ABCD matrix for refraction by a hyperbolic interface, we formulate analytical expressions for the concerned coupling efficiencies and evaluate them using few computations. The elliptic-core single-mode fiber has already emerged as a candidate in a polarization-conserving fiber optic sensor, in coherent fiber optical communication, etc. Therefore, our analysis, which to our knowledge is this first theoretical investigation in this context, will be extremely useful for the design of optimum launch optics involving an elliptic-core single-mode fiber. In addition, this analysis will be useful in the case of any inherent noncircularity that may arise due to fabrication problems in the circular core fiber.