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Tunable, Single-Wavelength Fiber Ring Lasers Based on Rare Earth-Doped, Double-Peanut Fiber Interferometers

Single-wavelength fiber ring lasers are demonstrated using rare earth-doped, double-peanut fiber interferometers (RD-DPFIs) as the tunable narrow-band filters. With the relatively stronger opto-thermal effect, thermal tunability of the Ytterbium-doped DPFI (YD-DPFI) is effectively enhanced, as compared to the Erbium-doped DPFI (ED-DPFI). The ED-DPFI achieves single-wavelength lasing with a side-mode suppression ratio (SMSR) of ≈50 dB, a 3 dB bandwidth of <0.02 nm, and a wavelength tuning range from 1531.92–1544.28 nm. The YD-DPFI achieves a single-wavelength lasing with a SMSR of ≈40 dB, a 3 dB bandwidth of <0.04 nm, and a wavelength tuning range from 1036.50–1027.25 nm. In addition, laser output stabilities are also investigated. The proposed lasers have high stability and cost-effectiveness which may be useful for optical communication and sensing systems.