Brillouin erbium (Er)-doped fiber laser (BEDFL) with single-frequency ultra-narrow line width

Abstract

The invention discloses a Brillouin erbium (Er)-doped fiber laser (BEDFL) with single-frequency ultra-narrow line width and aims to realize stable single-frequency Brillouin laser output in an annular cavity of the BEDFL. The BEDFL consists of a pump laser with narrow line width, a circulator, an Er-doped fiber amplifier (EDFA) capable of realizing bidirectional amplification, a section of singlemode fiber (SMF), a narrow-band optical filter and a fiber coupler. In the invention, the EDFL capable of realizing bidirectional amplification is placed in front of the SMF, Brillouin pump light is pre-amplified firstly and then injected into the SMF so as to improve the Brillouin pump power and further realize higher Brillouin gain in a shorter optical fiber; in addition, the EDFA also can be used for amplifying backscattered light so as to compensate cavity loss of the laser and realize higher-power Brillouin laser output. Therefore, the invention has the beneficial effects of solving the conflict between the short SMF and high Brillouin gain and realizing stable single-frequency BEDFL output and develops a novel hybrid gain type EDFL with ultra-narrow line width.

Description

technical field [0001] The invention relates to a fiber laser, in particular to a single-frequency ultra-narrow linewidth Brillouin-doped erbium fiber laser. Background technique [0002] Ultra-narrow linewidth fiber lasers have become an important development direction of fiber lasers due to their unique low phase noise characteristics. They are widely used in distributed fiber optic sensing and interferometric fiber optic sensing systems to reduce noise and improve detection sensitivity. According to different gain media, ultra-narrow linewidth fiber lasers are mainly divided into stimulated scattering fiber lasers and doped fiber lasers. The Brillouin fiber laser (BFL) uses the nonlinear Brillouin gain in the fiber, and the linewidth can reach below kHz or even sub-Hz level. important applications in communication systems. But the Brillouin gain coefficient of ordinary single-mode fiber is small (~10 -11 m / W), it is necessary to precisely control the length of the reso...

AI Technical Summary

Problems solved by technology

However, the Brillouin gain in the short fiber is small, and it is easy to excite the erbium-doped fiber laser mode, which competes with the BEFL laser mode, and cannot form a stable BEFL laser output.

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