Tapered Waveguides Produced by Ion Exchange in Glass With a Nonuniform Electric Field

Abstract

A method of manufacturing waveguides that are tapered in depth and formed by an electric field assisted ion exchange technique in glass is presented. The method relies on the creation of a nonuniform electric field distribution within the glass during the exchange process. This is achieved by creating a large number of narrow strip electrodes, which form the cathode during the field-assisted exchange process. All of the cathode electrodes are at the same potential during the exchange, which makes the manufacturing process particularly simple. Both planar and channel tapered waveguides can be formed by this technique and are characterized by prism coupling and interferometer measurements, respectively. A model for the taper, which is based on conformal mapping calculations for the nonuniform electric field, is developed and compared with measurements. The method allows for the manufacture of both tapered and uniform guides on the same substrate