An ultra-narrow linewidth fiber laser capable of suppressing relaxation oscillations

Abstract

The present application discloses an ultra-narrow linewidth fiber laser capable of suppressing relaxation oscillation. The fiber laser sequentially includes a pump laser source, a first wavelength division multiplexer, a phase-shift grating, an erbium-doped fiber, A second wavelength division multiplexer, an isolator and a coupler; a feedback module is arranged between the coupler and the pump laser source; the laser is divided into output light and feedback light in the coupler; the feedback light input into the feedback module to form a feedback signal; the feedback module is configured to: according to the change value of the output power of the pump laser source, use the feedback signal to adjust the driving current of the pump laser source to suppress relaxation oscillation noise. The present application suppresses the relaxation oscillation noise of the ultra-narrow linewidth fiber laser by means of photoelectric feedback, so that the intensity noise of the ultra-narrow linewidth fiber laser at the relaxation oscillation frequency is reduced by nearly 20 dB.

Description

technical field [0001] The present disclosure generally relates to the technical field of lasers, and in particular, to an ultra-narrow linewidth fiber laser capable of suppressing relaxation oscillation. Background technique [0002] Ultra-narrow linewidth fiber lasers are widely used in distributed fiber sensing and other fields due to their good monochromaticity, high energy conversion rate, compact structure, and high reliability. The application of high-precision distributed optical fiber sensing has high requirements for laser noise performance, especially relaxation oscillation noise characteristics. [0003] There are relaxation oscillations in the process of laser establishment. When the laser is turned on, it is equivalent to giving a step signal to its pump source; due to the sudden change of the laser pump source, the number of inverted particles and the number of photons in the laser changes drastically, which makes the laser output light show the characteristi...

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Problems solved by technology

When the laser is turned on, it is equivalent to giving a step signal to its pump source; due to the sudden change of the laser pump source, the number of inversion particles and the density of photons in the laser change drastically, so that the output light of the laser shows the characteristics of relaxation oscillation; When the pump source of the laser works continuously under constant current drive, the relaxation oscillation still exists; the existence of the relaxation oscillation causes the output light of the laser to be unstable, that is, the intensity noise of the laser has a peak at the relaxation oscillation frequency; The existence of oscillation noise limits the application in fields such as high-precision distributed optical fiber sensing

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