OPTICAL WAVE-GUIDE INTENSITY MODULATORS BASED ON A TUNABLE ELECTRON-DENSITY MULTIPLE QUANTUM-WELL STRUCTURE

With a recently developed semiconductor heterostructure it has become possible to tune continuously the electron density in multiple quantum wells. Here we demonstrate the first electro-optic waveguide intensity modulators based on this concept. We achieve a 22 dB ON/OFF ratio for 9 V applied at 1.54 μm wavelength in a rib waveguide electroabsorption modulator. Electrorefractive devices include a waveguide Mach-Zehnder interferometer with an active length 650 μm operating at 1.58 μm wavelength with 5.4 V half-wave voltage. We show that the operating voltage can be further reduced by operating the Mach-Zehnder modulators in push-pull configuration.