Wavelength-Spacing Adjustable Dual-Wavelength Dissipative Soliton Resonance Thulium-Doped Fiber Laser

A dual-wavelength dissipative soliton resonance thulium-doped fiber laser based on nonlinear optical loop mirror (NOLM) has been demonstrated. In this laser, mode-locking is achieved based on equivalent saturation absorption of the NOLM, while the dual-wavelength operation is attributed to the online birefringent fiber filter composed of a polarizer and a section of polarization-maintaining fiber (PMF). The wavelength spacing of dual-wavelength spectrum can be adjusted through changing the PMF length, and the central wavelengths can be tuned through rotating the polarization controllers. It is also found that at the two central wavelengths of the dual-wavelength pulse, switchable single wavelength mode-locked pulse can be generated. In addition, noise-like pulses with broadband spectra can be generated, when two kinds of mode-locking mechanisms conflict. The dual-wavelength dissipative soliton resonance thulium-doped fiber laser has important potential applications in the laser detection, sensing and other fields. Its rich dynamics also provides a system platform for basic research on laser physics.