Beam waist controlled vertical optical path conversion using integrated curved micro mirror for silicon photonics

Abstract

The optical input/output (I/O) of silicon (Si) photonics is a significant challenge in terms of its practical application. We recently demonstrated a vertical optical I/O using a 45°curved micro mirror. In this paper, the beam conversion controllability of the curved micro mirrors was studied. Different design curved micro mirrors were fabricated and those beam conversions were evaluated. The beam waist of the reflected light was successfully controlled by tuning the curvatures of the mirror. The experimental data were well agreed with simulation results. The coupling efficiency improvement between the mode mismatched fibers (a single-mode fiber and a spherical lensed fiber) was also demonstrated by using the curved mirror. Owing to the beam waist conversion, the coupling efficiency was improved by 3.3 dB. Very flat spectral characteristics were also obtained.