Single-longitudinal-mode narrow-linewidth fiber laser based on double-coupling fiber ring and Mach-Zehnder filter

Abstract

The invention discloses a single-longitudinal-mode narrow-linewidth optical fiber laser based on a double-coupling optical fiber ring and a Mach-Zehnder filter. The laser comprises a first optical isolator (1), a 980nm semiconductor laser (2), a 980 / 1,500nm wavelength division multiplexer (3), an erbium-doped fiber (4) with a concave cladding structure, an optical circulator (5), a non-pumped erbium-doped fiber (6), a fiber bragg grating (7), a passive resonant cavity (8) based on a double-coupling fiber loop and a Mach-Zehnder filter, a polarization beam splitter (9), a 1 * 2 optical coupler(10) and a second optical isolator (11), wherein the optical coupler (8) is composed of a first 2 * 2 optical coupler (12), a second 2 * 2 optical coupler (13) and a third 2 * 2 optical coupler (14).According to the passive resonant cavity based on the double-coupling optical fiber ring and the Mach-Zehnder filter, the two double-coupling optical fiber rings and the Mach-Zehnder filter are formed, the passive resonant cavity can serve as a narrow-band mode selection device to restrain multimode oscillation in the resonant cavity, and the non-pumped erbium-doped optical fiber serves as a saturable absorber; and the ultra-narrow band filtering effect can enable the annular cavity to realize stable single-frequency laser output. The laser has the advantages of narrow linewidth, low noise, high signal-to-noise ratio, simple structure and easiness in integration with an optical fiber system, and has huge potential in the fields of precision laser ranging, optical fiber communication, optical remote sensing and the like.

Description

technical field [0001] The invention relates to a ring-cavity single-frequency fiber laser, in particular to a single-longitudinal-mode narrow-linewidth fiber laser based on a double-coupled fiber ring and a Mach-Zehnder filter. Background technique [0002] Due to its high output laser quality, high power conversion efficiency, low pumping threshold, wide tuning range, compact structure and easy integration, excellent coherence characteristics and easy compatibility with optical fiber communication systems, etc. High-quality light source in. Narrow-linewidth fiber lasers are widely used in fiber optic sensing, fiber optic remote sensing, and high-precision spectroscopy due to their advantages of narrow linewidth and low noise. [0003] Cavity structures for single-frequency narrow-linewidth fiber lasers include linear cavities, traveling-wave ring cavities, and composite cavities. Due to the standing wave effect, the elongated cavity forms space-burning holes in the gain ...

AI Technical Summary

Problems solved by technology

Due to the standing wave effect, the elongated cavity forms space-burning holes in the gain medium, resulting in multi-longitudinal mode oscillations, resulting in broadening of the optical spectrum linewidth

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