Abstract

A multiple-branch tapered channel waveguide has been developed for coupling GaAs semiconductor laser source radiation into a multichannel Ti:LiNbO₃ optical array modulator. The step-index guiding wave region was fabricated by first rf sputter depositing Corning 7059 glass on Corning 2947 microscope slides, which were used as the substrate material. A shadowing technique was used during the sputtering process to produce a slowly increasing taper along the direction of propagation in the waveguide. Strip-channel waveguides were formed by masking off the guiding wave region and dry etching using an ion milling technique. The initial input channel is designed to collect radiation efficiently from the GaAs laser source. This initial input channel is then divided into two identical single-mode branches. After a distance each branch is divided into an additional set of identical single-mode branches. This process is repeated until the number of branches equals the number required for input into the array modulator. Losses produced by this multiple-branching geometry are discussed along with optimization of the branching geometry.

© 1988 Optical Society of America