Figure 1
From: Quasi mode-locking of coherent feedback random fiber laser
Schematic of quasi mode-locking of coherent feedback Q-switched random fiber laser and diagram of the laser cavity.
(a) Schematic of the Q-switched mode-locking random fiber laser. Reflector: fiber reflector with average reflectivity ≥97.5%, GSA: graphene saturable absorber, Coupler: 1:99 coupler with 1% port as output, PC: polarization controller, WDM: wavelength division multiplexer, EDF: Erbium doped fiber, RD-FBG: random distributed FBG array, inset: detail schematic of graphene based saturable absorber. (b) Nonlinear transmission of GSA. (c) Reflection and transmission spectra of the RD-FBG. (d) Schematic diagram of the laser cavity. L represents the geometric length between fiber reflector and the RD-FBG, ΔLi represents the random optical path length within the RD-FBG due to multi-reflection. The dashed rectangles with different colors reveal the relationship of mode oscillations for Regime-I and Regime-II.
