VARIABLE LIGHT ATTENUATOR, OPTICAL MODULE, LIGHT AMPLIFIER AND OPTICAL COMMUNICATION SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide a variable light attenuator of simple constitution and low loss, and to provide an optical module and a light amplifier having optical characteristics independent of a temperature by using the variable light attenua tor. SOLUTION: A packaging part 3 having a tension applying function is formed so as to cover a fiber grating part 2, The transmission loss characteristics of a long cycle fiber grating is varied by utilizing the thermal expansion difference caused by the difference of materials of the fiber grating part 2 and the packaging part 3. Thereby obtained variable light attenuator is incorporated in the optical module and the light amplifier whose temperature dependency are reduced as the result.