Wavelength Tuned Laser Based on Few-mode Long-period Fiber Grating

We construct a comb filter based on the dislocation splicing between optical fibers. Using the mode switching properties of few-mode long-period fiber gratings (FM-LPFG) and the interference effect of dislocation splicing, single-wavelength, dual-wavelength, three-wavelength and four-wavelength tunable laser generation are produced in the laser. In addition, by adjusting the polarization state and power in the cavity, a high-quality ultrafast laser pulse output with a wavelength of 1567.72 nm and a signal-to-noise ratio maintained above 61 dB is achieved. The switchable multi-wavelength all-fiber lasers have potentially important applications for laser processing, wavelength-division multiplexing and signal processing.