Tunable and switchable dual-wavelength passively mode-locked Bi-doped all-fiber ring laser based on nonlinear polarization rotation

We demonstrate a tunable and switchable dual‐wavelength passively mode‐locked Bi‐doped all‐fiber ring laser by using nonlinear polarization rotation (NPR) technique. Exploiting the spectral filtering effect caused by the combination of the polarizer and intracavity birefringence, the wavelength separation of dual‐wavelength mode‐locked pulses can be flexibly tuned between 2.38 and 20.45 nm. Taking the advantage of NPR‐induced intensity‐dependent loss to suppress the mode competition, the stable dual‐wavelength pulses output is obtained at room temperature. Moreover, the dual‐wavelength switchable operation is achieved by simply rotating the polarization controllers (PCs). (© 2011 by Astro Ltd., Published exclusively by WILEY‐VCH Verlag GmbH & Co. KGaA) (© 2011 by Astro Ltd., Published exclusively by WILEY‐VCH Verlag GmbH & Co. KGaA)