Random fiber laser based on artificially controlled backscattering fibers.

Abstract

The random fiber laser (RFL), which is a milestone in laser physics and nonlinear optics, has attracted considerable attention recently. Most previously reported RFLs are based on distributed feedback of Rayleigh scattering amplified through the stimulated Raman-Brillouin scattering effect in single-mode fibers, which require long-distance (tens of kilometers) single-mode fibers and high threshold, up to watt level, due to the extremely small Rayleigh scattering coefficient of the fiber. We proposed and demonstrated a half-open-cavity RFL based on a segment of an artificially controlled backscattering single-mode fiber with a length of 210m, 310m, or 390m. A fiber Bragg grating with a central wavelength of 1530nm and a segment of artificially controlled backscattering single-mode fiber fabricated by using a femtosecond laser form the half-open cavity. The proposed RFL achieves thresholds of 25mW, 30mW, and 30mW, respectively. Random lasing at a wavelength of 1530nm and extinction ratio of 50dB is achieved when a segment of 5m erbium-doped fiber is pumped by a 980nm laser diode in the RFL. A novel RFL with many short cavities has been achieved with low threshold.