Chang, J.-Y.J.-Y.ChangLiao, Y.-S.Y.-S.LiaoLu, H.-H.H.-H.LuGONG-RU LIN2020-06-112020-06-112006https://www.scopus.com/inward/record.uri?eid=2-s2.0-33750323326&doi=10.1364%2fOE.14.009743&partnerID=40&md5=6f000734f2e9d702e779f024d2f0db61By controlling the output coupling ratio, we demonstrate a novel wavelength-tunable L-band Erbium-doped fiber laser (EDFL) with a maximum tuning range up to 58 nm (from 1567 to 1625 nm) by controlling its output coupling ratio between 1% and 99%. The L-band EDFL is configured by using a bi-directionally dual-wavelength pumped EDFA in close-loop with an output coupler of tunable coupling ratio and an air-gap inserted FC/PC connector pair. Such an EDFL exhibits a quantum efficiency of 42% and an ultra-high power conversion efficiency of 37% under optimized pumping scheme, providing the small-signal gain and output power of ˜34 dB and 91 mW, respectively. Low variation of <1.2 dB on channel power, power fluctuation of 0.04% and a narrow linewidth of 0.03 nm are obtained. © 2006 Optical Society of America.Closed loop control systems; Erbium compounds; Laser tuning; Quantum efficiency; Semiconductor doping; Signal processing; Coupling ratio; Erbium-doped fiber laser (EDFL); Optimized pumping; Power fluctuation; Fiber lasersjournal article10.1364/OE.14.0097432-s2.0-33750323326