Multi-stage combined optical device having multiple channels

摘要

A multi-stage combined optical device having an improved structure which can detect incident light power using a single optical isolator. The multi-stage combined optical device includes a first collimator for collimating a ray emitted from a first optical fiber, an optical isolator having a first polarizer for transmitting an incident ray in a birefringent manner into an ordinary ray and an extraordinary ray, a Faraday rotator for rotationally transmitting the incident ray, and a second polarizer for inversely transmitting the incident ordinary ray and extraordinary ray, sequentially disposed on an optical path, a second collimator for focusing the light transmitted through the second polarizer onto a second optical fiber, a third collimator facing the light receiving plane of the first polarizer and disposed at a position different from that of the first collimator, for focusing a ray emitted from a third optical fiber, and a fourth collimator facing the light emitting plane of the first polarizer and disposed at a position different from that of the second collimator, for focusing a ray emitted from the third collimator via the optical isolator onto a fourth optical fiber. Also, the multi-stage combined optical device further includes a tap formed on a light receiving plane facing the first collimator of the first polarizer, a first photodetector for receiving a first incident ray reflected from the tap and detecting the optical power of the first incident ray, and a second photodetector for receiving a second incident ray reflected from the tap and detecting the optical power of the second incident ray.