Efficient InGaAsP/InP multiple quantum well waveguide optical phase modulator

We report an InGaAsP/InP multiple quantum well optical phase modulator which has a high phase modulation efficiency and low loss modulation over the entire 1.5-1.56 μm fiber band. For a 4-mm-long device, π phase modulation requires a modulation voltage of only 0.6 V at 1.49 μm and 1.1 V at 1.55 μm wavelength. The absorption modulation for a 0-5 V bias change is negligible at 1.55 μm, rising to 0.7 cm^-1 at 1.49 μm. The spectral dependence of the electrorefraction from the quantum-confined Stark effect has also been measured for the first time over a wide continuous wavelength range. Far from the absorption edge the electrorefraction decreases approximately as the square of the energy detuning.