| 摘要 |
PURPOSE:To inhibit the output of a light signal to the output terminal of a port supplied with the light signal by reflecting the light signal projected from an input fiber end part of a port group through a reflector consisting of a rod lens and a diffraction grating. CONSTITUTION:Optical fibers 31-35 have input light fiber end parts M1, M2, and T1, and optical fibers 34 and 36 have output fiber end parts M'1, M'2, and R1. The rod lens connected thereto has a refractive index distribution with nearly squarelaw characteristics in the radial direction and is a quarter as long as zigzag pitch of light beam. A diffraction grating 41 with a period l1 and a diffraction grating l2 with a period a half said period are formed on the end surface of the lens on both sides of an x axis; and the half of each grating period is formed of a dielectric film with thickness lambda/4 and no diffracted light of degree 0 is present. Light from the input fiber end parts M1, M2, and T1 is made incident to the diffraction gratings 41 and 42 and primary diffracted light is inputted to the end part of an output fiber other than its projection port and never returns to its projection station. |
