Light modulator and optical fiber communication system

TLDR: In this paper, the authors proposed a light modulator and an optical fiber communication system capable of suppressing a relative strength noise and improving an SN ratio, where a light distributor equally distributes a light carrier A to 1st and 2nd light carriers A1, A2.

Abstract: PROBLEM TO BE SOLVED: To provide a light modulator and an optical fiber communication system capable of suppressing a relative strength noise and improving an SN ratio. SOLUTION: A light distributor 11 equally distributes a light carrier A to 1st and 2nd light carriers A1, A2. An 180 deg. distributer 12 distributes an RF subcarrier signal B to 1st and 2nd RF subcarrier signals B1, B2 of which phases are unutuaily inverted by 180 deg.. An electro-optical modulator 13 modulates the 1st optical carrier A1 by the 1st RF subcarrier signal B1 and outputs a 1st optical signal C1. An electro-optical modulator 14 modulates the 2nd optical siganal A2 by the 2nd RF subcarrier signal B2 and outputs a 2nd optical signal C2. Photodiodes 6, 7 respectively convert the 1st and 2nd optical signals C1, C2 transmitted through optical fibers 4, 5 into 1st and 2nd electric signals D1, D2. An 180 deg. synthesizer 8 inverts the phase of the signal D1 by 180 deg. and synthesizes the inverted signal and the 2nd electric signal D2.