Optical attenuator

Abstract

Abstract PURPOSE:To prevent the deterioration in the code error rate characteristic in a digital transmission system and S/N and distortion in an analog transmission system by forcing an optical attenuation plate having the prescribed relation between construction and disposition into an optical transmission system. CONSTITUTION:An optical fiber 1 on an input side, a lens 3, an optical attenuation plate 10 coated with multilayered metallic or dielectric films having an optical attnuation characteristic on one surface of a glass substrate, a lens 4 and an optical fiber 2 on an output side are disposed along the advance direction of light. The plate 10 is disposed diagonally to a light beam to prevent the reflected return light from the plate 10 from coupling to the fiber 1. The relation between the construction and disposition of the plate is so determined as to satisfy the equation 1 to prevent the light beam which is multiple-reflected by the plate 10 and passes the plate 10 from coupling to the fiber 2. In the equaton 1, (d) denotes the diameter of the incident beam, (t) the thickness of the parallel flat optical attenuation plate, (n) the refractive index of the optical attenuation plate, theta1 the angle between the incident beam to the optical attenuation plate, and the direction perpendicualr to the incident face of the optical attenuation plate.

Inventors

• 👤 Kenichi Sato
• 👤 健一 佐藤
• 👤 Masatoshi Saruwatari
• 👤 猿渡　正俊

Bibliographic Details