Highly unbalanced GaAlAs-GaAs integrated Mach-Zehnder interferometer for coherence modulation at 1.3 μm

A novel integrated III-V semiconductor waveguide modulator specially designed to generate an optical delay of 100 mu m is presented. This is achieved by simultaneous propagation of the TE fundamental mode in both of the arms of a highly unbalanced Mach-Zehnder interferometer with a 29 mu m length difference between both arms. In order to minimize the losses in this complex curved structure, trenches were etched on the outsides of curved sections. The modulator has a contrast of 34%, a switching voltage of 6 V with a 10 mm long electrode and is suitable for the transmission and multiplexing of signals by coherence modulation of light in an optical fiber network powered by a short coherence source, such as a 1.3 mu m superluminescent diode. (C) 1999 Published by Elsevier Science B.V. All rights reserved.