Tunable single-frequency single polarization fiber laser based on polarization-preserved fiber grating

Abstract

The invention discloses a tunable single-frequency single polarization fiber laser based on polarization-preserved fiber grating. An a port of a wavelength division multiplexer (2) in the fiber laser is connected with a tail fiber of a pump source (1), an er-doped single mode fiber (3A) is connected between a b port of the wavelength division multiplexer (2) and an incident fiber of an isolator (3), a c port of the wavelength division multiplexer (2) is connected with a c port of a polarization-preserved fiber circulator (7); an a port of a coupler (5) is connected with a tail fiber of the isolator (3), a polarization controller (6) is connected between a b port of the coupler (5) and an a port of the polarization-preserved fiber circulator (7), a c port of the coupler (5) outputs tunablesingle-frequency single polarization laser with wavelength range of 1552.0nm-1552.8nm; a b port of the polarization-preserved fiber circulator (7) and one end of a non-pumping er-doped polarization-preserved fiber (3B) are in 0-degree fusion joint, the other end of the non-pumping er-doped polarization-preserved fiber (3B) and an a port of a polarization modulator (8) are in 45-degree fusion joint, and a b port of the polarization modulator (8) and an incident fiber of double refraction polarization-preserved fiber grating (9) are in 45-degree fusion joint. The laser output by the tunable single-frequency single polarization fiber laser has the characteristics of wavelength tunable single frequency, ultra-narrow line width less than 1KHz, single polarization more than or equal to 20dB andtunable range more than or equal to 0.5nm.

Description

Tunable single-frequency and single-polarization fiber laser based on polarization-maintaining fiber grating technical field The present invention relates to a laser, more particularly, to a tunable single-frequency fiber laser based on a polarization-maintaining fiber grating. Background technique Fiber lasers are widely used in optical communication, optical sensing, spectroscopy and other fields. Among them, single-frequency fiber laser is a single-frequency working laser light source with extremely narrow linewidth. As a single longitudinal mode working laser, the linewidth can reach kHz level and has a long coherence length. It is suitable for high-end testing, sensors, fields of scientific research. There are many ways to obtain narrow-linewidth single longitudinal mode fiber laser output, such as using fiber grating to form a linear cavity structure with distributed feedback or distributed Bragg reflection, a ring cavity structure with unidirectional operation, an...

AI Technical Summary

Problems solved by technology

However, since the cavity length of the laser is inversely proportional to the free spectral range, the longitudinal mode interval of the long-cavity ring cavity is very narrow, which brings difficulties to the single longitudinal mode laser output

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