Switchable and tunable dual-wavelength Yb-doped fiber lasers with asymmetric exposure phase-shifted long-period fiber gratings

A switchable and tunable dual-wavelength Yb-Doped fiber laser was implemented with an asymmetric exposure phase-shifted long-period fiber grating inserted in the ring cavity. The asymmetric exposure phase shifted long-period fiber grating, which was fabricated by a CO2 laser, acts as a dual-wavelength filter with anisotropic transmission spectrum under different states of polarization. The wavelength switching and tuning is attributed to the polarization and bending characteristics of the asymmetric phase-shifted long-period fiber gratings respectively. It shows the possibility to achieve simultaneously switchable and tunable dual-wavelength Yb-Doped fiber lasers in an all-fiber format.