| 摘要 |
PURPOSE:To easily obtain the optical phase detection system which is low in demodulation error by compensating the residual phase offset in the phases of the signal light and locally emitted light in optical 90 deg. hybrid by respectively two optical phase compensation plates and further adjusting the offset so as to have an ideal phase relation. CONSTITUTION:The signal light S1' and the locally emitted light L0' are respectively previously so subjected to polarization compensation as to attain the linear polarization state forming 45 deg. angle with polarized light separating elements 1a, 1c and are then separated respectively to P and S polarized light components S3' and L3' and S2' and L2'. The respective polarized light components S2'. S3' of the signal light are maintained at the same phase by adjusting these components with the optical phase compensation plates 9a, 9b and 90 deg. phase difference is generated between the polarized light components L2' and L3' of the locally emitted light; thereafter, the respective polarized light components S3', L3', S2', L2' are multiplexed by multiplexing elements 1b, 1d to obtain an I component and a Q component. The residual phase offset by the error at the time of packaging of the element is compensated in this way and the remodulation error is lowered by adjusting the phase relations. |
