| 摘要 |
Provided are a PLC-type DP-QPSK demodulator and an optical transmission system that uses this demodulator, wherein connection loss between a polarization beam splitter and a 90-degree hybrid circuit is reduced, and manufacturing cost is also reduced. In one embodiment, the PLC-type DP-QPSK demodulator (1), which is for receiving DP-QPSK signals, is provided with one PLC chip (3) that has a planar lightwave circuit formed thereon. Input ports (In1-In3) are provided at the input end (4), and output ports (Out1-Out8) are provided at the output end (5) of the PLC chip (3). Integrated within the planar lightwave circuit is: the polarization beam splitter (30) that splits the DP-QPSK signal into an X-polarization QPSK signal and a Y-polarization QPSK signal; and two of the aforementioned 90-degree hybrid circuits (41, 42) that mix the X-polarization QPSK signal and an X-polarization local oscillation light, and the Y-polarization QPSK signal and a Y-polarization local oscillation light, respectively, split each of the QPSK signals into I and Q components intersecting orthogonally, and output those components. |
