BY-PASS OPTICAL SWITCH HAVING MONITOR FUNCTION

摘要

PURPOSE:To omit a mechanical movable part to expand the life of the title device and to reduce the consumption of electric body by using a liquid crystal cell as a switching element and changing voltage to be impressed to the liquid crystal to make the liquid crystal execute prescribed operation. CONSTITUTION:Signal light inputted from a terminal 1a is inputted to a beam splitter 9 of which the ratio of transmission to reflection is set up to a prescribed value and the reflected signal light is bent rectangularly at its optical path by a rectangular prism 13a and outputted to an output terminal 2a. The liquid crystal cell 11 sealing nematic liquid crystal rotates the polarizing surfaces of rectangular 2 polarized light rays separated by a polarizing splitter 10 for separating the incident signe light into rectangular 20 polarized light rays and synthesizing the separated light rays by 90 deg. in the going and returning ways in accordance with an externally impressed voltage and passes the rectangular 2 polarized light rays without rotation. A rectangular prism 12 having a reflecting film for returning the optical path, a prism 13b for bending one optical path out of the rectangular 2 polarized light rays rectangularly to synthesize the rectangular 2 polarized light rays separated by the splitter 10 and prism 13c for bending the optical poath of the signal light transmitted through the splitter 10 rectangularly are arranged on one end surface of the cell 11.