Tuning and wavelength switching erbium-doped fiber ring lasers by controlled bending in arc-induced long-period fiber gratings

In this paper, we report a simple method for the production of an all-fiber, tunable and wavelength switchable erbium-doped fiber ring laser (EDFRL). We use the shift in resonance wavelength and notch-depth of arc-induced long-period fiber gratings (LPFGs) when it is subject to controlled bend to suppress some wavelength gain and promote lasing in a selective way in a fiber laser system. By changing the bending radius, the operating wavelength of the EDFRL can be tuned from 1526 to 1538 nm and then switched and tuned from 1568 to 1557 nm. The maximum separation measured between laser lines was ～42 nm. This is one of the highest laser separations reported in a wavelength switching operation of an EDFL using a single LPFG as wavelength selective filter.