Y-branch optical wavelength multi/demultiplexers by ion exchange in glass

A simple and accurate multisheet Brewster angle measurement technique has been developed to measure substrate indices. Both K{dollar}sp+{dollar} and Ag{dollar}sp+{dollar} ion-exchanged optical waveguides in glass substrates were characterized for infrared wavelengths {dollar}lambda=1.152{dollar} and 1.523{dollar}mu m.{dollar} For the characterization of Ag{dollar}sp+{dollar} ion-exchange waveguide, the WKB method has been modified to handle the index truncation point at the waveguide boundary inside the substrate accurately. An explicit and stable finite-difference vector beam propagation method has also been developed for efficient numerical simulations of the guided-wave optical devices.; A modified Y-branch wavelength multi/demultiplexer (abbreviated as WDM) for {dollar}lambda=1.31{dollar} and 1.55 {dollar}mu m{dollar} was designed and optimized by the beam propagation method (abbreviated as BPM). The device, made by K{dollar}sp+{dollar} ion-exchange in glass with a sputtered Al{dollar}rmsb2Osb3{dollar} strip on one branch, can provide high extinction ratios and wide bandwidth. It was successfully fabricated. The measured results of over 20db extinction ratio agree well with the BPM design simulations. A new Y-branch WDM made by K{dollar}sp+{dollar} and Ag{dollar}sp+{dollar} ion-exchanges was proposed and fabricated. It eliminates a difficult fabrication process, involving an Al{dollar}rmsb2Osb3{dollar} strip waveguide, and still provides the other merits of the first device. Its feasibility has been experimentally established. To simplify the fabrication process further, an asymmetric Mach-Zehnder WDM by one step ion-exchange for both two-wavelength and three-wavelength ({dollar}lambda=0.98mu{dollar}m being the third wavelength) was proposed. The BPM simulations show some improvements in several aspects over other types of demultiplexers.