[OPTICAL REVIEW Vol. 9, No. 1 (2001) 9-12]
An ASE Reduction Filter Using Cascaded Optical Fiber Grating Couplers in EDFA Repeater
Hirohisa YOKOTA*, Kenji KAMOTO, Jun-ichi IGARASHI, Norihiko MOURI and Yutaka SASAKI
Department of Systems Engineering, Faculty of Engineering, Ibaraki University, 4-12-1, Nakanarusawa, Hitachi, Ibaraki 316-8511 Japan
(Received October 17, 2001; Accepted October 29, 2001)
A new configuration for an ASE reduction filter in EDFA repeaters for WDM optical transmission systems using optical fiber grating couplers (FGCs) was proposed and first demonstrated. The filtering characteristics of the proposed filter for amplified single wavelength signal and 2-channel WDM signals using EDFA were identified. It was found that the filter was effective to improve SNR in optical domain by reducing ASE noise. The required FGC characteristics for the filter were theoretically predicted under the condition that the total filter loss did not exceed 3 dB. More than 70 % of drop efficiency was required in each FGC for the application of the proposed filter to an 8-channel WDM system using EDFA repeaters.
Key words: optical fiber coupler, fiber Bragg grating, erbium-doped fiber amplifier, optical repeater, ASE noise reduction, WDM transmission