Patent ID: 8280200

Claim:
A polarization conversion device which converts a polarization state of a light input to a first waveguide to output the converted light from the first waveguide, comprising: a mode converter which performs TE to TM mode conversion or TM to TE mode conversion of the light input to the first waveguide and outputs the light; and a polarization separator which receives the light passed through the mode converter, and separates the received light into a first light, a TE/TM mode of which has been converted by the mode converter, and a second light, a TE/TM mode of which has not been converted by the mode converter, to output the first light to the first waveguide, wherein the light of TE mode or TM mode input to the first waveguide passes through the polarization separator to be input as it is to the mode converter, and the output light from the mode converter is input to the polarization separator, and the polarization separator separates the output light, which has been output from the mode converter and input to the polarization separator, into a light of mode different from that of the light input to the first waveguide and a light of mode same as that of the light input to the first waveguide, and outputs the light of mode different from that of the light input to the first waveguide, as the first light, to the first waveguide, while outputting the light of mode same as that of the light input to the first waveguide, as the second light, to a second waveguide different from the first waveguide.