Patent ID: 9608736
Date: 2017-03-28
CPC Classifications: G02B,H04B,H04J

Claim:
1. A planar lightwave circuit, comprising: a substrate with a straight groove being formed therein; a signal light input port formed in said substrate and receiving polarization-multiplexed signal light; a local oscillator light input port formed in said substrate and receiving polarization-multiplexed local oscillator light; a first planar filter part fitted into said groove and separating said signal light into a signal light component comprising a first polarization state and a signal light component comprising a second polarization state; a second planar filter part fitted into said groove and separating said local oscillator light into a local oscillator light component comprising the first polarization state and a local oscillator light component comprising the second polarization state; a first interference part formed in said substrate; a second interference part formed on a side of said substrate opposite to the side of said first interference part across the groove; a first waveguide connected to said signal light input port and connected diagonally to a reflection surface of said first planar filter part; a second waveguide connected to said first interference part and to said first planar filter part, and guiding said signal light component comprising the first polarization state; a third waveguide connected to said second interference part and to said first planar filter part, and guiding said signal light component comprising the second polarization state; a fourth waveguide connected to said local oscillator light input port and also connected diagonally to a reflection surface of said second planar filter part; a fifth waveguide connected to said first interference part and to said second planar filter part, and guiding said local oscillator light component comprising the first polarization state; and a sixth waveguide connected to said second interference part and to said second planar filter part, and guiding said local oscillator light component comprising the second polarization state.