OPTICAL CIRCUIT ELEMENT

PURPOSE:To offer the optical circuit element which can greatly reduce crosstalk and is easily manufactured and reducible in cost. CONSTITUTION:This optical circuit element has three 1st, 2nd, and 3rd ports 1, 2, and 3, has such nonreciprocity that light incident from the 1st port 1 is projected from the 2nd port 2, light incident from the 2nd port 2 is projected from the 3rd port 3, and light incident from the 3rd port is projected from none of the ports, and also has a cyclic function of polarization nondependency and nonreciprocity. Then two sets 21 and 22 of composite polarizing elements, a Faraday rotation element 4, and an analyzing element are arranged in order from the 1st port 1 to the 2nd port 2 and a permanent magnet is arranged on the Faraday rotation element 4; and parallel flat plate type birefringent crystal is used for the composite polarizing elements 21 and 22 and analyzing element 3 and the length of the analyzing element 3 is set to length obtained by multiplying the length of the composite polarizing elements 21 and 22 by a subduplicate of 2.