MULTIPLEXING SYSTEM UTILIZING PLANE OF POLARIZATION

摘要

PURPOSE:To simplify an apparatus of an optical system by using a photodetector constituted by packaging two APDs onto the same chip and attaching polarizing plates which are respectively different in the axial directions to the front of the photodetecting surfaces. CONSTITUTION:A light signal of which the polarization direction is in an X axis and a light signal of which the polarization direction is in a Y axis are fed through a polarization plane maintaining type optical fiber 1. The photodetector 8 is constituted by disposing the two APD9 and APD10 on the same chip in such a manner that the respective photodetecting surfaces are positioned on the same plane and in the same direction. The polarizing plate 9a is attached to the photodetecting surface of the APD9 and the polarizing plate 10a is similarly attached to the photodetecting surface of the APD10. The plate 9a allows the transmission of only the light signal of which the polarization direction is in the X axis. The plate 10a allows the transmission of only the light signal of which the polarization direction is in the Y axis. The number of the apparatus of the optical system is thus decreased and the package over the entire part of the device is made smaller in size.