Mismatch considerations in laser diode to single-mode circular core triangular index fiber excitation via upside down tapered hemispherical microlens on the fiber tip

We present a theoretical investigation of coupling efficiency of a laser diode to a single-mode circular core triangular index fiber coupling via upside-down tapered hemispherical microlens on the tip of the fiber in presence of possible transverse and angular offsets. Using the relevant ABCD matrix formalism for such type of coupler, we prescribe analytical formulations of coupling efficiencies in presence of the said mismatches. Using the prescribed expressions, we evaluate the coupling efficiencies in presence of transverse as well as angular misalignments. The concerned execution involves little computation. The results found will benefit the designers and packagers working in the field of optimum launch optics.