A feedback-injected Fabry-Perot laser diode filtering technique for side-mode suppression and linewidth reduction of erbium-doped fiber lasers

Abstract

By adding a fiber-pigtailed Fabry-Perot laser diode (FPLD) into a close-loop erbium-doped fiber amplifier (EDFA) ring cavity. and feedback-injecting the FPLD biased at just below threshold and the EDFA each other via directional couplers, we demonstrate a low-cost band-pass filtering technique for constructing narrow linewidth erbium-doped fiber laser (EDFL) with ultrahigh side-mode suppression ratio (SMSR). Under an output coupling ratio of 90%, the mutually injection-locked EDFL-FPLD link exhibits a maximum output power and SMSR of up to 98.6 mW and 49.6 dB at wavelength 1561.37 nm,. respectively. Wavelength tuning of up to 6 nm can be achieved by tuning the temperature and fine adjusting the below threshold driven current of FPLD. The minimum spectral linewidth at 3dB-decay of as small as 0.017 nm measuring by commercial optical spectrum analyzer with limited resolution bandwidth of 0.01 nm are observed. The stabilities in power, SMSR, peak wavelength of +/-0.01 mW, +/-0.5 dB, and +/-0.025 nm, respectively, are also determined. (C) 2003 Elsevier Science B.V. All rights reserved.