Low voltage hetero-nipi wavelength modulators

Summary form only given. A wavelength modulator with a hetero-nipi core has been made. The device, grown by molecular beam epitaxy on a semi-insulating GaAs substrate, had a waveguide core containing two complete n-i-p-i periods. Each intrinsic layer contained 75-Å GaAs quantum wells with 45-Å AlAs barriers. A 400-μm device was then tested as a phase modulator. A phase shift of 180°C was obtained at 860 nm with negligible absorption losses at 1.5 V applied, and at 845 nm with 3 dB of electroabsorption loss and only 0.8 V applied. The figure of merit, defined as phase shift per mm length and volt, was as high as 560°/Vmm. The combination of short length and low voltage results from the use of the hetero-nipi structure, which allows a large field to be applied across the quantum wells with a small voltage