JPS55117124A - Photo circuit element - Google Patents

Abstract

PURPOSE: To obtain the photo circuit element having a function as a circulator of light by combining a plurality of circuit elements such as double refractive crystal plates, Faraday effect elements and rotatory polarization crystal plates by way of a reflector.

CONSTITUTION: Non-polarized light from an optical fiber 11 via lens 12 is admitted into a double refractive crystal plate 13 and is divided to two parallel normal ray and abnormal ray depending upon the polarization directions. The normal ray is changed of direction by 60° by a reflector 40 of a triangular prism, passes through a rotatory polarization crystal plate 26, Faraday effect element 24 to be rotated of its polarization plane 90°, diagonally advances within a double refractive crystal plate 23 and is coupled to an optical fiber 21 by a lens 22. On the other hand, the abnormal ray is polarized 60° by the reflector 40 and enters the double refractive crystal plate 33, but it advances diagonally in the crystal plate 33 and is not coupled to the optical fiber 31. In this way, respectively 50% of the lights out from the optical fibers 11, 21, 31 are respectively coupled to the optical fibers 21, 31, 11, thus the element has a function as a circulator.

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