| 摘要 |
In polarization rotation circuits of the prior art, it was necessary to form a silicon nitride layer, a process not typically implemented when fabricating a silicon waveguide circuit. Implementing polarization rotation circuit functionality in an integrated optical circuit requires an additional process step for the exclusive purpose of forming the silicon nitride layer, leading to longer manufacturing times and more complicated manufacturing equipment. In this polarization rotation circuit, the waveguide width in the center core section of the polarization rotation circuit is constricted, whereby optical wave intensity does not become concentrated exclusively in the center core section, and there is greater susceptibility to structurally asymmetric effects. Due to the configuration of this polarization rotation circuit, polarization conversion can be brought about efficiently, despite a structure having a silicon waveguide only, and without forming a silicon nitride layer or the like. Moreover, through various configuration examples of mode conversion circuits in which the waveguide spacing is not excessively constricted, there may be provided configurations with which circuit length can be shortened, and tolerances during manufacture made looser. |
