Abstract

We report the design and realization of a high-performance InGaAsP/lnP multiple quantum-well waveguide phase modulator based on the quantum confined Stark effect. Use of the quaternary InGaAsP for the well material enabled a high phase-modulation efficiency to be obtained with a low intensity modulation throughout the 1.5-1.55 μm fiber band. A 180° phase modulation of TE polarized light was obtained in a 4 mm long device under 5 V bias with just 0.6 V at 1.49 μm wavelength and 0.9 V at 1.55μm wavelength. The phase shift increased quadratically with applied bias, in accordance with theory, giving a total phase shift of 1100° (TE) and 830° (TM) at 1.4 μm at 6 V, with 500° (TE) and 400° (TM) at 1.55μm. The refractive index change associated with the measured phase shift was found to have an approximate inverse-square dependence on the energy detuning from the exciton resonance. The intensity modulation associated with the phase modulation was very low. At 1.49 μm, there was just 0.7 cm^-1 measured excess loss for TE light, with 1.6 cm^-1 for TM light. This excess loss decreased at longer wavelengths and vanished at around 1.54 μm. No optical intensity dependence was discernible up to the maximum cavity power of 10^? W/m². Device speed was limited to −1 GHzby RC charging times.

© 1990 Optical Society of America