Compact Mach-Zehnder space switch combining bandfilling and the quantum confined stark effect

Integrated optical crossconnects and add-drop multiplexers require low-loss polarization independent MZI space switches. We have developed a quantum well material in which the electrorefraction due to the Quantum Confined Stark Effect and bandfilling are added. The operating wavelength in an undoped InGaAs/InAsP quantum well was first determined by limiting the excess waveguide loss to 0.2 dB/cm and the electroabsorption loss to 0.1 dB/mm. Without doping, a polarization independent Dn of 7.8.10-4 was obtained at 100 kV/cm. Bandfilling increases Dn to 2.10-3 at 100 kV/cm, resulting in a phase shifter length of 0.46 mm in push pull configuration