Laser diode to monomode elliptic core fiber excitation via hemispherical lens on the fiber tip: Efficiency computation by ABCD matrix with consideration for allowable aperture

Employing Gaussian field distributions for both the source and the fiber, we report a simple theoretical prediction of the coupling efficiency of a laser diode to a single-mode elliptic core fiber via hemispherical lens on the fiber tip. The analysis is based on ABCD matrix for hemispherical lens under paraxial approximation. Our formalism takes care of the allowable aperture of the hemispherical lens. The present analysis prescribes analytical expressions for the coupling efficiency and the concerned calculations are executable by pocket calculator.