Low-switching-voltage InGaAsP/InP waveguide interferometric modulator for integrated optics

An InGaAsP/InP electrooptic Mach-Zehnder modulator consisting of two 3-dB Y-branch couplers and phase modulation arms is fabricated by the metal-organic vapor-phase epitaxy growth method. A schematic illustration and cross section of the interferometric modulator as well as the current-voltage characteristics of the arms are shown. The modulator is formed by a waveguide having almost the same cross-sectional configuration as a double-heterostructure laser diode. The switching voltage of 4.5 V applied to one arm of the modulator results in an excitation of about 7 dB.<>