Switchable multi-wavelength fiber lasers based on asymmetric biconical fiber tapers

In this paper, switchable multi-wavelength erbium-doped fiber lasers (MW-EDFLs) are proposed and experimentally demonstrated. An in-fiber Mach–Zehnder interferometer (IFMZI) composed of asymmetric biconical fiber taper (ABFT) pairs is integrated into the all-fiber ring cavity for multi-wavelength filtering. This laser can stably emit single-, dual-, or triple-wavelength outputs by fine-tuning the polarization controller. A high optical signal to noise ratio of 58.5 dB is obtained for the output spectra. The maximum wavelength shift is 0.08 nm and the power fluctuation in all laser emissions is recorded at 1.64 dB. •Multi-wavelength erbium-doped fiber laser generating single-, dual-, and triple-wavelength emissions is demonstrated.•An in-fiber Mach–Zehnder interferometer composed of asymmetric biconical fiber taper pairs is exploited as the comb filter.•A maximal optical signal to noise ratio of 58.5 dB is obtained.•Favorable temporal stability with the maximum wavelength shift of 0.08 nm and power fluctuation of 1.64 dB is presented.