Polarization-maintaining all-fiber 2-μm pulse seeded by the soliton self-frequency shift of 1.5-μm pulse

This study used erbium-doped fiber laser to pump highly nonlinear fibers to generate soliton self-frequency shift (SSFS), and implemented a full fiber polarization maintaining 2 μm master oscillator power amplifier (MOPA) system based on a 1.5 μm pulse laser frequency shift. By using saturable absorber (SA) mode-locked pulses as seed sources, a traditional soliton with a center wavelength of 1560-nm, and a repetition rate of 67-MHz was obtained. After two-stage amplification, the seed pulse can output a maximum average power of 982mW. After two stages of amplification, it can output a maximum average power of 982mW. Cascade a segment of polarization maintaining high nonlinear fiber (PM-HNLF) after the amplification stage, the amplified optical pulse generates soliton self-frequency shift in the PM-HNLF. In this work, a small core PM1550 fiber is used as the high nonlinear fiber, which can ultimately be frequency shifted to 2060nm, with a signal-to-noise ratio of (SNR) 73.32dB. The system is entirely constructed with polarization maintaining fibers, without any free space optical components, with strong anti-interference ability, good stability, and high integration.