Quadruple-wavelength tunable and dual-wavelength switchable ultrafast fiber laser

We propose a quadruple-wavelength tunable and dual-wavelength switchable ultrafast fiber laser by incorporating four fiber Bragg gratings. The tunable operations depend on the losses induced by intracavity polarization controllers. By appropriately setting the states of PCs, quadruple-wavelength picosecond solitons can be realized at 1530, 1540, 1550 and 1560 nm, respectively. When the losses are suitable, solitons with two different wavelengths can reach the gain balance, and the dual-wavelength operations are switched among the four wavelengths. These results demonstrate that the proposed fiber laser offers potential opportunities in exploiting flexibly switchable multi-wavelength pulse sources.