Fig. 1. Schematic diagram of vortex Raman fiber oscillator based on acoustically-induced fiber grating (AIFG)

Fig. 2. (a) Transmission spectrum of LP₀₁ mode at different loaded frequencies; (b) Fitted curve between the electrical frequency and wavelength

Fig. 3. (a) Output signal power as a function of pump power and beam spots at corresponding power; (b) Spectrum at the maximum output power

Fig. 4. (a) Original light intensity distribution; (b1)-(b4) Beam profiles after the linear polarizer, where the red arrows refer to the polarization direction; (c), (d) Self-interference patterns