Switchable and tunable multi-wavelength fiber ring laser employing a cascaded fiber filter

Abstract

• We propose a novel cascaded hybrid fiber filter. • A switchable and tunable multi-wavelength fiber laser. • This laser has excellent robustness because of no core-offset splicing point. • This laser operates more stably compare to the previous similar works. A switchable and tunable multi-wavelength fiber laser based on cascaded hybrid fiber filter (CHFF) is proposed and demonstrated. The CHFF is composed of a single ellipsoid hybrid structure optical fiber filter (SE-HSOFF) and a Sagnac loop interferometer. Here the SE-HSOFF consists of single mode fiber (SMF)-few mode fiber (FMF)-SMF, and there is an ellipsoidal structure fabricated by SMF-FMF. It has the function of realizing the switchability of fiber laser. The Sagnac loop interferometer incorporated with a segment of polarization maintaining fiber (PMF) is used as a tuning component. By adjusting the state of polarization controller (PC), the laser can operate in single-, dual-, triple- and quadruple-wavelength laser states, and the lasing wavelength can be tuned by about 10 nm when it operates in dual-wavelength state. The optical signal to noise ratio (OSNR) is larger than 30.0 dB. This laser has excellent robustness because there is no core-offset splicing point and operates very stably in every output state at room temperature.