Channel-spacing switchable multi-wavelength fiber ring laser with one segment of polarization maintain fiber

A channel-spacing switchable multi-wavelength fiber ring laser by using one segment of polarization-maintain fiber (PMF) is experimentally demonstrated. By adjusting the polarization controllers, the wavelength spacing could be efficiently switched between 0.2 nm and 0.4 nm. Compared with the multi-wavelength fiber laser using the PMF filter previously reported, the channel-spacing switchable operation can be realized by using only one segment of PMF without changing the length of PMF. Meanwhile, the lasing output, including the lasing locations and the number of the lasing lines, can also be flexibly adjusted through the wavelength-dependent polarization rotation mechanism