Optical vertical couplers by ion exchange in glass.

摘要

Planar and channel optical waveguides fabricated by field-assisted {dollar}Ksp+{dollar}-{dollar}Nasp+{dollar} ion exchange in soda-lime glass are studied. An optical characterization of planar surface guides for a given set of fabrication conditions has been performed to determine the refractive index profile. Parallel to this, the ion-exchange diffusion process has been modelled numerically to predict the concentration profile of these waveguides. Direct measurements of the profiles using electron microprobe analysis has been carried out.; The results of the characterization were used in the design and fabrication of a novel vertically integrated optical directional coupler. This device, composed of single-mode surface and buried ion-exchanged waveguides, allows for the optical fiber coupling to the buried guide and efficient power transfer to the surface guide, where the light can be detected by a modelled {dollar}GaAs{dollar} photodetector. An improved version of the device using a sputtered {dollar}Alsb2Osb3{dollar} surface guide allows for edge coupling to the detector. Calculations of the {dollar}GaAs{dollar} absorption coefficient show an optimum behavior for a given thickness of {dollar}Alsb2Osb3{dollar}.; An implicit finite-difference vector beam propagation method (FD-VBPM), that was improved to account for graded-index profiles, has been developed and used in the design of both directional-coupler structures. Finally, a three-dimensional FD-VBPM algorithm was implemented for the channel-guide version of the improved coupler.