Influence of gap between laser and optical waveguide

In the letter, an approximate analysis is developed for calculating the reflection and transmission coefficients at the junction discontinuity between two planar dielectric waveguides when there is a dielectric gap between them. The analysis is applied to the junction between a heterojunction laser and a planar optical waveguide with an airgap, and results are presented showing the variation of the reflection and transmission coefficients with the gapwidth.