Multiwavelength GaAs rib waveguide directional-coupler switch with ’’stepped Δβ’’ Schottky electrodes

Abstract
An electro‐optic waveguide directional‐coupler switch has been fabricated in GaAs by liquid‐phase epitaxy, photolithography, chemical etching, and electroplating. The Schottky electrodes, overlaying each single‐mode rib waveguide, are cut midway along the device length to allow the electrical optimization of each switching state (’’stepped Δβ’’ configuration) in a wavelength range (1.0–1.3 μm) useful for optical‐fiber communications. The device exhibits good power isolation for both states (at least 19 dB and up to 32 dB) with reverse driving voltages of less than 30 V, at 1.06, 1.15, and 1.32 μm. Both states have been obtained at 1.06 μm by switching one single voltage, a convenient way in spite of some power penalty to take full advantage of the large potential bandwidth (1 GHz) of the switch.