| 摘要 |
PURPOSE:To obtain a device simple in constitution that can be operated by feeble light signals and small in attenuation to light signals by controlling a polarization controller basing on a control signal obtained by light heterodyne/ homodyne detecting output light of the second light emission terminal. CONSTITUTION:Only polarized light component polarized in the direction perpendicular to the face of paper is taken out from the second light emission terminal 21 of a polarized light separation circuit 6 and led to a light detector 8 made up of InGaAs-PIN.PD, and light from a light transmitting path 1 and light from a local oscillation light source 7 are mixed and light heterodyne detected. The first and second polarized light controller 31, 32 constituted of PZT and single mode optical fiber are cascade connected between the light input terminal of the light transmitting path 1 and the first input terminal 3 of a light coupler 2, and polarized light is controlled by applying pressure to the single mode optical fiber from the direction perpendicular to the optical axis of the single mode optical fiber by voltage driven PZT. |
