Switchable, tunable and highly stable multi-wavelength fiber laser based on a spectral filter

In this work, a switchable and tunable multi-wavelength erbium-doped fiber laser based on a spectral filter is presented. Here, the filter is formed by polymer and silicon layers at the tip of an optical fiber. The laser emission wavelengths are mainly determined by the position where the most intense fringes of the reflectivity spectrum of the filter occurs. Moreover, the number of laser emissions are controlled and switched by using a variable optical attenuator inserted into the laser cavity. In this way, single-, dual-, triple-, and quadruple-laser emissions can be obtained within the long operating span from ~1526-~1565 nm. Additionally, the multi-wavelength laser emissions had a side mode suppression ratio 36.48 dBm, a minimum wavelength spacing of ~3.6 nm, and the best peak power difference was 0.45 dB. Besides, the wavelength shift and peak power fluctuation were 0.095 nm and 3.14 dB, respectively, over half an hour. Finally, the emissions of the multi-wavelength laser can be tuned within a tunable range of 2.93 nm by taking advantage of some thermal properties of the Si and polymer layers.