Active control of polarization state of the light in InP waveguide.

We demonstrate an InP deep-ridge type multi-quantum-wells (MQWs) waveguide-based active polarization control scheme by using two positive-intrinsic-negative diode phase shifters. The polarization state of horizontal/vertical linearly polarized input light is rotated along the ± 45°-linear polarization axis on the Poincaré sphere by 45°-eigenmode-rotated first phase shifter 1 and subsequently rotated along the vertical/horizontal axis by second normal phase shifter 2. The rotation of the eigenmode axes is obtained by using the surface plasmonic effect. The effective index of the waveguide is changed via quantum-confined Stark effect in the MQW core. The length of each phase shifter is 240 µm. The applied reverse bias voltages are -2.7 V and -1.95 V for the phase shifter 1 and 2, respectively.