Polarization-independent waveguide modulators using 1.57- mu m delta -strained InGaAs-InGaAsP quantum wells

We fabricated a multiple-quantum-well waveguide modulator incorporating two tensile S-strained layers, within a nominally lattice matched well, that act to provide bias-independent Stark shift for both the light and heavy holes. We report results for two waveguide geometries. One is a 2.3- mu m-wide ridge single-mode waveguide that was deep-etched 0.7 mu m below the active region to ensure that the confinement factor for both the TE and TM modes are nearly equal. The other was a broad-area (slab) multimode waveguide. For both geometries, transmission measurements indicate polarization insensitivity within 3 dB for 2.5 V of reverse bias over the 1.600-1.630- mu m wavelength range