Passive mode-locked fiber laser based on low-mode fiber saturable absorber

Abstract

The invention discloses a passive mode-locked fiber laser based on a low-mode fiber saturable absorber, and relates to the field of ultra-short fiber lasers. The passive mode-locked fiber laser uses a ring cavity structure and comprises a pump source, a wavelength division multiplexer, a gain fiber, a non-polarization maintaining isolator, a polarization controller, the low-mode fiber saturable absorber and a coupler. The low-mode fiber saturable absorber is composed of an input single-mode fiber, a low-mode fiber and an output single-mode fiber which are fused in turn. The saturable absorption characteristic of the low-mode fiber is based on the nonlinear multi-mode interference effect in the low-mode fiber. The saturable absorber used by the passive mode-locked fiber laser is a real all-fiber saturable absorber and has the advantages of low cost, simple structure and high damage threshold so as to greatly improve the stability of the mode-locked fiber laser and have wide application prospect.

Description

technical field [0001] The invention relates to the field of laser technology and nonlinear optics, in particular to a passive mode-locked fiber laser based on a few-mode fiber saturable absorber. Background technique [0002] Due to the advantages of easy operation, compact structure, stable performance, and low cost, passive mode-locked fiber lasers have very important scientific applications in the fields of optical fiber communication, material fine processing, optical frequency combs, lidar, laser medical treatment, and laser spectroscopy. value. Saturable absorbers are the key devices in passive mode-locked fiber lasers, which are mainly divided into two categories: saturable absorbers based on the saturable absorption characteristics of materials (for example: semiconductor saturable absorbing mirrors and two-dimensional lasers represented by graphene materials) and all-fiber saturable absorbers. Among them, the saturable absorber based on the saturable absorption c...

AI Technical Summary

Problems solved by technology

The existing multimode fiber saturable absorbers usually use two types of multimode fibers, graded and step, but the number of high-order modes excited by these two types of multimode fibers is large (about tens to hundreds of modes) and It is difficult to control, resulting in the following problems in the existing multimode optical fiber saturable absorber: (1) due to the large number of modes and complex transmission characteristics, it is difficult to theoretically study the mechanism of its saturable absorption characteristics; (2) more The number of modes makes the mode coupling complex and disordered, so it is difficult to prepare a saturable absorber with stable performance; (3) In the application of high-energy fiber lasers, due to the large number of high-order modes, the energy loss at the melting point is serious, and it is easy to appear heat damage

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