Side pump signal beam combiner for realizing flat-topped light beam and preparation method thereof

Abstract

The invention discloses a side pump signal beam combiner for realizing flat-topped beams and a preparation method thereof, and belongs to the technical field of laser beam shaping. The main signal optical fiber has at least two layers of waveguide structures; the refractive index of the inner-layer waveguide structure is higher than that of the outer-layer waveguide structure; the main signal optical fiber is a multimode optical fiber for laser with a transmission wavelength, the side arm input optical fiber is subjected to fused biconical taper processing to be attached to the interior of a waveguide structure outside the innermost layer waveguide structure of the main signal optical fiber, and the fusion length L of the side arm input optical fiber is 0 mm (L is smaller than or equal to200 mm; the fusion depth H is 0 [mu] m (H is less than or equal to 500 [mu] m; the diameter D of the fusion area is larger than or equal to 5 micrometers and smaller than or equal to 500 micrometers,the optical waveguide mode that signal light in the side arm input optical fiber enters the main signal optical fiber is changed by controlling the tapering fusion length, diameter and depth of the side arm input optical fiber, and therefore output of flat-topped mode light spots is achieved in the main signal optical fiber.

Description

technical field [0001] The invention relates to the technical field of laser beam shaping, in particular to a side-pump signal beam combiner for realizing a flat-hat beam and a preparation method thereof. Background technique [0002] The laser beam is generally a Gaussian beam, and the Gaussian beam has a high intermediate intensity, and the intensity in the radial direction gradually decreases along the Gaussian profile. The top-hat beam concept is a laser beam with a uniform distribution of light intensity. In a high-power and high-energy system, most of the energy of the Gaussian beam is concentrated in the central part, which is easy to damage the optical device. At the same time, the Gaussian beam will bring non-uniform heating to the device and affect the beam quality. In practical applications, the Gaussian beam is very easy to penetrate the material due to the high central light intensity. When the flat-top beam is used for laser engraving, the light intensity is u...

AI Technical Summary

Problems solved by technology

However, after different modes of light are introduced into the optical fiber, a specific refractive index distribution is required to obtain a flat-topped spot energy distribution. The same optical fiber is not universal for different incident lights. In addition, a specific refractive index distribution can be prepared without continuous change. optical fiber preform rod, the required process and cost are relatively high

[0009] At present, the fiber side coupling scheme has been proposed, but it is currently used for the pump light transmission in the fiber laser, the signal light is transmitted in the main signal fiber, the pump light is transmitted in the side arm input fiber, and the opposite side arm enters the main signal fiber. The beam energy distribution of the signal fiber is not required

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