Fig. 1. Schematic of experimental setup. LD, laser diode; EYDF, erbium/ytterbium co-doped fiber; SMF, single-mode fiber; ISO, isolator; VOA, variable optical attenuator; PD, photodetector; OSC, oscilloscope; FBG, fiber Bragg grating; OSA, optical spectrum analyzer.

Fig. 2. Power and spectral properties of the EYRFL. (a) Output power versus pump power. (b) Output spectra at different pump powers. (c) Variation of −3dB and −20dB bandwidth of EYRFL with pump power. (d) Optical spectrum filtered by the narrow-bandwidth tunable filter. Dashed line: full spectrum of EYRFL; red line: in the central part; green line: detuned by 0.4 nm; purple line: detuned by 0.8 nm.

Fig. 3. (a) Temporal intensity dynamics and (b) intensity PDF of filtered random lasing radiations at different spectral locations. Green line: filtered in the central part; red line: detuned by 0.4 nm from the center; blue line: detuned by 0.8 nm from the center. The black dashed line in (b) represents the exponential distribution.

Fig. 4. Intensity PDFs of the filtered central part spectrum of EYRFL at different operating regimes. Insert: calculated intensity ACF of the filtered central part spectrum of EYRFL.