CN103904535A

CN103904535A - Cladding light filtering device for high-power optical fiber laser

Info

Publication number: CN103904535A
Application number: CN201410127040.2A
Authority: CN
Inventors: 李进延; 廖雷; 彭景刚; 邢颖滨; 蒋作文; 戴能利; 李海清; 杨旅云; 王朝
Original assignee: Huazhong University of Science and Technology
Current assignee: Huazhong University of Science and Technology
Priority date: 2014-03-31
Filing date: 2014-03-31
Publication date: 2014-07-02
Anticipated expiration: 2034-03-31
Also published as: CN103904535B

Abstract

The invention discloses a cladding light filtering device for a high-power fiber laser. The device comprises one or more sections of double-cladding optical fibers. The double-cladding optical fibers can partially strip a protection layer and an external cladding in the laser output direction from the small stripping area to the large stripping area at intervals to enable an internal cladding to be exposed, the exposed internal cladding is coated with filtering materials, and the light filtering device is fixed to a heat dissipation metal material or a water cooling plate. According to the cladding light filtering device, the damage to an optical fiber structure is small, light filtering is even, the phenomenon that the temperature of some filtering points is excessively high in the non-even filtering process is avoided, and system stability is improved.

Description

A kind of high-capacity optical fiber laser cladding light filtering device

Technical field

The present invention relates to fiber laser and fiber amplifier, particularly the filtering device of unnecessary cladding light in a kind of high power all optical fibre structure fiber laser.

Background technology

Since E Snitzer in 1988 describes double clad pumping optical fiber laser first, double clad pump technology has been widely used in the field such as fiber laser and fiber amplifier.In recent years, along with high brightness laser diode pumping technology and the development of large mould area double-cladding doped fiber manufacturing process, the power output of single double-cladding fiber laser improves rapidly.Fiber laser, as a class new laser, has the advantages such as conversion efficiency is high, volume is little, good beam quality, is the most potential laser of 21 century.High-capacity optical fiber laser generally comprises two types: one is direct oscillation mode; Another is laser amplifier type.They are all the double clad gain fibres by being mixed with rare earth ion, the pumping laser of injection is changed into signal laser, ideal situation is: signal optical fibre is limited in obtaining in fibre core enough amplifications, and pumping laser is fully absorbed by gain fibre in covering.But reality is really not so, at the output of optical-fiber laser, in the inner cladding of doubly clad optical fiber, still have the unnecessary light of a part, this part light is mainly derived from: the pump light not being completely absorbed; The spontaneous emission light (ASE) that oscillator or amplifier produce in the time of work; Fusion point place reveals or is reflected into the flashlight of fiber cladding.If this part unnecessary light is unclean by filtering, will to the beam quality of fiber laser and below the device in link produce very large harm.

At present roughly can be divided into two classes about the filtering method of high-capacity optical fiber laser cladding light: a class is that the inner cladding of double clad is carried out to micro-processing processing, Chinese patent CN102255235A and CN102255227A propose to remove optical fiber jacket and coat, process some V-type grooves or optical fiber inner cladding is carried out to roughening processing at optical fiber inner cladding, the light in covering is leaked.These class methods have caused damage to the quartz part of optical fiber itself, make the intensity variation of optical fiber, and the method operates and realize more complicated in addition.Another kind of method is to utilize optical cement or metal to reveal unnecessary cladding light, Chinese patent CN101718916A proposes after the surrounding layer of doubly clad optical fiber and coat removal, coat the optical fiber gel of high index of refraction and reveal unnecessary cladding light, and Chinese patent CN103197440A proposes by carrying out the unnecessary cladding light of filtering in the method for inner cladding plating metal on surface film.The defect that these class methods exist is not consider temperature homogeneity problem, cladding light can leak out in a large number in extremely short distance, excess Temperature in easily producing more among a small circle, work as poor heat radiation, and thermal accumlation very easily causes optical fiber to burn to a certain extent time, and then bring destructive impact to whole fiber ring laser system.

Therefore, in the time of filtering high-capacity optical fiber laser cladding light, must adhere to two principles: 1, cladding light goes in should scattering to air as much as possible, instead of is absorbed by the material of optical fiber surface; 2, cladding light should be as much as possible in the filtering of optical fiber surface piecewise uniform, and can not in extremely short distance, concentrate filtering.

Summary of the invention

For above defect or the Improvement requirement of prior art, the invention provides a kind of filtering device of high-capacity optical fiber laser cladding light, its object is unnecessary cladding light in effective filtering fiber laser, solve thus the even filtering that realizes cladding light, avoid the too high technical problem of local temperature.

This device has a section or the multistage of cascade of the double clad energy-transmission optic fibre of high-capacity optical fiber laser or amplifier out; every section of double clad energy-transmission optic fibre surface along in laser transmission direction by divesting that area is ascending and compartment of terrain divests protective layer and the surrounding layer of part; make inner cladding out exposed, above exposed inner cladding, scribble filter.

The surrounding layer of doubly clad optical fiber is strapped in a large amount of cladding lights in covering and transmits, and by changing the refractive index of outsourcing layer, can make cladding light leak from inner cladding.It is more that surrounding layer divests, and it is more that cladding light is revealed, and controls the leakage efficiency that divests area and can control cladding light of surrounding layer, with reference to aforesaid way, protective layer and surrounding layer processed and be conducive to cladding light and reveal at each covering place of divesting equably.

The present invention adopts by divesting the ascending and method of compartment of terrain peeling optical fibre protective layer and inner cladding of area; the Area Ratio divesting by controlling optical fiber; select refractive index suitable; the filter that leaded light performance and heat conductivility are good; when being propagated in optical fiber, cladding light evenly leaks from optical filtering; and as much as possible scattering in air go, the heat simultaneously producing when filtering by metal material is delivered in cooled plate.

The present invention has following beneficial effect:

1, compared with existing additive method, this method has only been destroyed partial protection layer and the inner cladding of optical fiber, has saved as much as possible the original structure of optical fiber from damage, and the damage to optical fiber when processing is less.

2, in this method cladding light along laser direction by evenly filtering, avoid local temperature too high, and compact conformation, be convenient to integratedly, can realize the filtering of higher-wattage cladding light.

Brief description of the drawings

Fig. 1 is that double clad energy-transmission optic fibre divests protective layer and surrounding layer schematic diagram with reference to pagoda-shaped;

Fig. 2 is the energy-transmission optic fibre schematic diagram after again applying according to pagoda-shaped;

Fig. 3 is for being fixed on schematic diagram on metal derby through cladding light filtering energy-transmission optic fibre after treatment;

This cladding light filtering device is applied in the schematic diagram in high-capacity optical fiber laser by Fig. 4.

Embodiment

Below in conjunction with accompanying drawing, the specific embodiment of the present invention is described further.It should be noted that at this, be used for illustrating for the explanation of these execution modes and understand the present invention, but do not form limitation of the invention.

Refer to Fig. 1 to Fig. 3, Fig. 1 is double clad energy-transmission optic fibre, and with reference to the area of the cabinet-type mode that divests from small to large, protective layer 4 and surrounding layer 3 are partly divested successively, expose glass inner cladding 2.Again according to Fig. 2, on expose the

optical fiber

5,6,7,8,9 of glass inner cladding, recoat and be covered with refractive index and be greater than glass, the filter that thermal conductivity and light conductivity are good and form optical filtering part 10,11,12,13,14, this filter can be ultra-violet curing glue, epoxide-resin glue or heat-conducting organic silica gel.As Fig. 3, will be fixed on metal copper billet or aluminium block 16 through again applying optical fiber 21 after treatment, the 17,18,19, the 20th, 4 screwed holes reserving, are closely fixed on metal copper billet or aluminium block in cooled plate with screw, realize good heat radiating.

Embodiment:

The present invention is as shown in Figure 4 applied to a high-capacity optical fiber laser output, the cladding light that filtering is unnecessary.This high-capacity optical fiber laser adopts straight cavity configuration, high reflective grid 24 and low reflective grid 25 form the necessary resonant cavity of laser, the laser that utilizes bundling device 23 that multiple semiconductor lasers 22 are exported is injected in resonant cavity, the 26th, fibre core 1 is 20 μ m, inner cladding 2 is the Yb dosed optical fiber of 400 μ m, it in chamber as gain media.The 28th, high-capacity optical fiber laser output emits, in order to prevent that laser from forming reflection at end face, done the processing of oblique octave to output.The front end emitting at output arranges above-mentioned filtering cladding light device 27; first the protective layer 4 to optical fiber and inner cladding 3 divest for 1:6:20:42:96 carries out pagoda-shaped from small to large with reference to divesting Area Ratio; divest partly and recoat and be covered with epoxide-resin glue at these again; utilize heat-conducting glue that optical fiber is fixed on metal copper billet, finally metal copper billet is fixed on radiating water cooling board.Experiment shows, in the time that laser output power reaches 600w, the temperature of cladding light filtering place remains on 45 degree left and right, and beam quality approaches diffraction limit, is better than beam quality before cladding light filtering.Illustrate that the method can be applied in the filtering of high-capacity optical fiber laser cladding light.

Those skilled in the art will readily understand; the foregoing is only preferred embodiment of the present invention; not in order to limit the present invention, all any amendments of doing within the spirit and principles in the present invention, be equal to and replace and improvement etc., within all should being included in protection scope of the present invention.

Claims

1. a high-capacity optical fiber laser cladding light filtering device; it is characterized in that: one section or the multistage of cascade with the double clad energy-transmission optic fibre of high-capacity optical fiber laser or amplifier out; every section of double clad energy-transmission optic fibre surface along in laser transmission direction by divesting that area is ascending and compartment of terrain divests protective layer and the surrounding layer of part; make inner cladding out exposed, above exposed inner cladding, scribble filter.

2. high-capacity optical fiber laser cladding light filtering device according to claim 1, is characterized in that, the refractive index of described filter is greater than 1.46, and light transmittance is greater than 60%, and conductive coefficient is greater than 2W/mK.

3. high-capacity optical fiber laser cladding light filtering device according to claim 1 and 2, described filter is ultra-violet curing glue, epoxide-resin glue or heat-conducting organic silica gel.

4. according to the high-capacity optical fiber laser cladding light filtering device described in any one in claim 1-3; it is characterized in that; the described optical fiber that scribbles filter is fixed on to heat conduction good, is carved with on the metal material of U-shaped groove, the internal diameter of this U-shaped groove is slightly larger than fiber optic protection layer.

5. high-capacity optical fiber laser cladding light filtering device according to claim 4, is characterized in that, the conductive coefficient of described metal material is greater than 200W/mK, and this metal material is fixed in cooled plate.