Butt-joint interfaces in InP/InGaAsP waveguides with very low reflectivity and low loss

Abstract

In this paper we report on the observation of reflection values <-50dB at activepassive\nbutt-joint interfaces in extended cavity Fabry-Pérot lasers and 0.19dB loss at\npassive-passive butt-joint interfaces. A three step growth process has been developed\nusing MOVPE with all metal-organic precursors. In the first epitaxy step, the active\nlayer stack is grown up to 200 nm above the index guiding layer. The passive regions\nare etched using a SiNx mask, afterwards those regions are re-grown up to the top of\nthe active regions. Finally the SiNx mask is removed and the top cladding is grown. We\nhave investigated the minimization of the butt-joint reflection by crossing the interface\nat different angles. Measurements showed that the butt-joint reflection is below -50dB\nfor angles above 12 degrees.