RECEIVING OPTICAL DEVICE FOR OPTICAL COMMUNICATION

摘要

PURPOSE:To selectively take in only communication light obtained by removing tracking light from received light, and to reduce a communication noise due to the tracking light and improve the SN ratio by providing an optical dispersing element on the optical path of the communication light. CONSTITUTION:The received light is converted into linear polarized light by passing through a 1/4-wavelength plate 9 and then made incident on a polarization beam splitter(PBS) 8. The received light which is reflected by the PBS 8 passes through a polarizing prism 7 for noise removal and is made incident on a dichroic beam splitter 4. The tracking light is reflected here and the communication light is transmitted. Part of the tracking light is mixed with the luminous flux having passed through the beam splitter 4. A spectral prism is provided on the optical path of this luminous flux and the tracking light is projected from the spectral prism in a different direction from the communication light. A convergence optical system 2 is arranged in a projection direction corresponding to the wavelength of the communication light and the communication light which is converged here is made incident on a communication photodetector 3.