Megahertz-Rate Swept Femtosecond Fiber Laser Source Based on Soliton Self-Frequency Shift

We report a high-speed wavelength-swept femto-second fiber laser source with controllable soliton self-frequency shift (SSFS). By applying an acousto-optic modulator (AOM) to intensity-modulate the ultrashort pulses outside the cavity, the source achieves high-speed wavelength scanning from 1576 nm to 1706 nm. The sweep rate reaches up to megahertz, overcoming the limitations of gain bandwidth and pulse buildup time in conventional intracavity operation. Also, we implement dispersive Fourier transform (DFT) technique to circumvent the speed limitations of optical spectrum analyzers (OSA), enabling real-time characterization of the wavelength scanning dynamics. This swept fiber source, with its unique combination of compact size, all-fiber structure, and high-speed capability, offers significant potential applications in rapid wavelength scanning and ultrafast detection.