Fig. 1. Schematic diagram of continuous Raman laser for observing laminar‒turbulent transition

Fig. 2. Comparison of laminar and turbulent state characteristics. (a)(b) Power evolution of laminar and turbulent states with roundtrip number; (c)(d) ACF images of laminar and turbulent states, and the insets show the corresponding time domain intensities; (e)(f) normalized intensity probability distribution for laminar and turbulent states respectively, and the insets show unlogarithmically processed data; (g)(h) phase evolution of laminar and turbulent states

Fig. 3. Laminar and turbulent states versus pump power and resonator length. (a) Reflection bandwidth of FBG is 0.8 nm; (b) reflection bandwidth of FBG is 1.0 nm

Fig. 4. Laminar‒turbulent images under different pump powers. (a) Intensity image of laser laminar state with a pump power of 0.8 W; (b) time-domain intensity curves with pump power of 0.8 W and 1.6 W; (c) intensity image of laser turbulent state with a pump power of 1.6 W; (d) spectral intensity curves with pump power of 0.8 W and 1.6 W, and the corresponding 3 dB spectral bandwidths are 0.12 nm and 0.39 nm, respectively

Fig. 5. Laminar‒turbulent images under different cavity lengths. (a) Intensity image of laser turbulent state with a cavity length of 700 m; (b) time-domain intensity curves with cavity lengths of 700 m and 1500 m; (c) intensity image of laser laminar state with a cavity length of 1500 m; (d) spectral intensity curves with cavity lengths of 700 m and 1500 m

Fig. 6. ACF and spectrum width as functions of pump power under different FBG reflection bandwidths (the blue dashed line is the minimum value 0.94 of ACF for laminar state, and the orange dashed line is the maximum width of the spectrum 15dFBG for laminar state). (a) 0.4 nm; (b) 0.8 nm; (c) 1.2 nm; (d) 1.6 nm