Thermal wavelength tunable all-polarization-maintaining thulium-doped NALM fiber laser

A wavelength tunable polarization-maintaining all-fiber thulium-doped source based on a nonlinear amplifying loop mirror (NALM) is demonstrated for dissipative soliton and stretched pulse operation. Transform-limited pulse durations down to 163 fs and 134 fs are supported for dissipative soliton and stretched pulse operation, respectively. The magnitude and center wavelength shift direction of the fiber-based tunable Lyot filter can be adjusted by heating different fiber sections and lengths. Due to the versatile nature of the fiber-based Lyot filter, the strength of the temperature shift coefficient and free spectral range can be optimized through the corresponding filter design.