| 摘要 |
PURPOSE:To eliminate mode dependency by providing a phase shifter that can independently change the phases of TE, TM modes between two pieces of 3dB coupling parts wherein the coeffts. of coupling of the TE, TM modes propagating in optical waveguides are made equal. CONSTITUTION:Two pieces of 3dB coupling parts I, II wherein the coeffts. of coupling of the TE, TM modes propagating in respective optical waveguides by the application of prescribed voltage to respective electrodes are made equal and which are eliminated of polarization dependency are provided in two pieces of parallel optical waveguides formed in a substrate having electrooptic effect, and further, a phase shifter III which can change the phases of the TE, TM modes mutually independently is provided at their intermediate. Hence, switching effect is realized by changing the phase of the TE mode and the mode dependency is eliminated by making the phases of the TE, TM modes equal, thus the optical directional coupler which has no polarization dependency and permits light power exchanging is obtained. |
