CN107907936A - Based on the optical fiber fusing suppressing method for reducing fibre cladding thickness - Google Patents

Abstract

The invention discloses a kind of based on the optical fiber fusing suppressing method for reducing fibre cladding thickness, it is used for the oscillation mode optical fiber laser of all -fiber mechanism, using the passive fiber in the oscillation mode optical fiber laser close to output terminal certain length as processing section, remove the coat of processing section and thickness processing is carried out to the fibre cladding of the processing section to reduce the thickness of the fibre cladding of the processing section.Step index optical fiber laser oscillator of the invention based on all optical fibre structure, therefore its is simple in structure, safety and stability is high, and handled by directly carrying out thickness to passive fiber to reduce the thickness of fibre cladding, it does not introduce other fusion points, extra loss is avoided, its operation difficulty is low, complexity is small, beneficial to reducing cost.

Description

Optical fiber fusing suppression method based on reducing fiber cladding thickness

technical field

The invention relates to the technical field of fiber lasers, in particular to a method for suppressing fiber fusing based on reducing the thickness of the fiber cladding.

Background technique

With the rapid development of optical fiber communication and high-power fiber lasers, the rapid growth of optical fiber transmission capacity in the communication field and the rapid increase of output power of high-power fiber lasers, the power (density) transmitted in optical fibers has also increased rapidly. This brings about a problem: when the optical fiber transmits extremely high power (density), the end face is damaged due to the influence of other factors such as optical fiber overheating and the environment (such as the end face of the optical fiber is contaminated with dust particles, or the end face is inadvertently touched by other The surface of the object, and the unreasonable local excessive bending of the optical fiber, etc.), a certain part of the optical fiber will absorb a large amount of laser energy and convert it into heat accumulation in the optical fiber, which will cause the local temperature of the optical fiber to rise sharply (even up to 10 ⁴ K level) resulting in fiber fusing. Optical fiber fusing refers to the extremely high temperature of the optical fiber core that produces high-temperature and high-pressure plasma in the optical fiber core. The high-temperature and high-pressure plasma propagates at a high speed in the optical fiber at a speed of m/s order, and punches out bullets in the optical fiber. Shaped cavity, which causes irreversible damage to the fiber core, even to the fiber cladding, and even other components on the fiber connection (such as gratings, etc.). Therefore, trying to suppress the fiber fusing phenomenon in the optical fiber has extremely important practical significance for the long-term normal operation of the optical fiber communication system and high-power fiber laser system, and improving the safety and stability of the entire system.

Japanese Patent Document 1 (method of terminating the fiber fuse by expanding the MFD of a part of the SMF, JPN, 4070111, 2002) with the publication number 4070111 discloses a method for suppressing optical fiber fusing, which mainly involves fusing a larger mode field The diameter of the fiber can be used to suppress the phenomenon of fiber fusing, but the splicing loss of the fiber with a small mode field and a large mode field diameter is very large, and the loss is difficult to control. If a series of different types of optical fibers with different mode field diameters are used for multi-stage fusion splicing to increase the mode field matching degree, this will not only affect the operational complexity, safety and stability of the entire system, but also greatly increase the manufacturing cost of the system .

The Japanese patent document 2 (method of terminating the fiber fuse by inserting the optical attenuator of a photonic crystal fiber type, JPN 3455921992) with the application number 345592 discloses a method for suppressing fiber fusing, which is mainly aimed at photonic crystal fibers, and photonic crystal fibers The waveguide structure is mainly determined by the structure of the air hole, so the low-loss splicing of the photonic crystal fiber is a complex and difficult to control problem, and the insertion of the optical attenuator itself will bring a large insertion loss to the system, so it is greatly This increases the loss of the entire system and reduces the transmission performance of the entire system.

In view of this, it is an urgent problem to be solved at this stage to provide a method for suppressing optical fiber fusing with low loss, simple operation, high safety and stability.

Contents of the invention

The purpose of the present invention is to overcome the above-mentioned technical deficiencies, and propose a fiber fusing suppression method based on reducing the thickness of the optical fiber cladding, so as to solve the problem that the optical fiber fusing suppression method in the prior art is complicated to operate and easily leads to large laser loss, low safety and stability. technical problem.

In order to achieve the above technical objectives, the technical solution of the present invention provides a method for suppressing fiber fusing based on reducing the thickness of the fiber cladding, which is used in an oscillation fiber laser with an all-fiber structure, and the passive fiber in the oscillation fiber laser A certain length near the output end is used as a treatment section, the coating layer of the treatment section is removed and the thickness of the fiber cladding of the treatment section is treated to reduce the thickness of the fiber cladding of the treatment section.

Compared with the prior art, the present invention is based on a step-refractive-index fiber laser oscillator with an all-fiber structure, so its structure is simple, its safety and stability are high, and the thickness of the passive fiber is directly processed to reduce the fiber cladding. The thickness, which does not introduce other welding points, avoids additional loss, and its operation difficulty is low, the complexity is small, and it is beneficial to reduce the cost.

Description of drawings

Fig. 1 is the connection structure schematic diagram of fiber laser of the present invention;

Fig. 2 is a schematic view of the corrosion treatment structure of the passive optical fiber of the present invention;

Fig. 3 is a schematic view of the surface of the fiber core where the fiber fusing phenomenon occurs.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

Please refer to Fig. 1, Fig. 2, the present invention provides a kind of fiber fusing suppression method based on reducing the fiber cladding thickness, it is used for the oscillation type fiber laser of all-fiber structure, the passive fiber in the described oscillation type fiber laser 6 is a certain length near the output end as the processing section 6a, remove the coating layer 63 of the processing section 6a and perform thickness treatment on the fiber cladding 62 of the processing section 6a to reduce the thickness of the fiber cladding 62 of the processing section 6a.

Wherein, the above-mentioned oscillating fiber laser can be formed by sequentially connecting a semiconductor laser 1, a fiber combiner 2, a first reflective grating 3, an active optical fiber 4, a second reflective grating 5, and a passive optical fiber 6;

Specifically as shown in Figure 1, the semiconductor laser 1 of the present embodiment can adopt a low-power semiconductor laser 1 with a watt-level output power, which can dissolve the coupling output fiber of the semiconductor laser 1 and the pump pigtail of the fiber combiner 2, The output end of the fiber combiner 2 is then fused with the first reflective grating 3, and one end of the active optical fiber 4 can be fused with the output end of the first reflective grating 3, and the other end is fused with the input end of the second reflective grating 5. The optical fiber 6 is fused with the output end of the second reflective grating 5, which can constitute a straight-cavity oscillating fiber laser, which is based on a step-refractive-index fiber laser oscillator with an all-fiber structure, and its output power can remain stable for a long time It is less sensitive to external mechanical vibrations, and its structure is simpler and easier to maintain than fiber lasers based on photonic crystal fibers with spatially coupled structures. Wherein, the first reflective grating 3 in this embodiment is a high reflective grating, and the second reflective grating 5 is a low reflective grating, and the active optical fiber 4 is preferably an active ytterbium-doped optical fiber.

The length of the above-mentioned passive optical fiber 6 is generally set to be 0.5-1.5 m, and 0.9 m is preferably used in this embodiment.

As shown in Figure 2, the passive optical fiber 6 includes an optical fiber core 61, an optical fiber cladding 62 and a coating 63 arranged sequentially from the inside to the outside. The physical cutting method can also be used. After the thickness treatment, the outer peripheral surface of the optical fiber cladding 62 of the processed section 6a can form a gradually increasing outer diameter from the middle to its two ends. Among them, in this embodiment, the method of corroding and dissolving the treatment section 6a by passing through the glass solvent is preferred, and the treatment uniformity is good.

The processing section 6a of this embodiment is close to the output end of the passive optical fiber 6, and hydrofluoric acid solution can be used for immersion and dissolution during specific treatment, which can reduce the thickness of the optical fiber cladding 62 of the processing section 6a, thereby helping to suppress the optical fiber fusing effect . When selecting the treatment section 6a, generally the length of the treatment section 6a is 0.5-2.5mm, and 2mm is preferably used in this embodiment, which is conducive to maximizing the improvement of the suppression effect.

When carrying out corrosion treatment, the concentration of hydrofluoric acid solution is generally 10～25%, is preferably 13%; The temperature of corrosion treatment is 15～25 ℃, specifically can control the temperature of hydrofluoric acid solution at 15～25 ℃ It is preferably at 17°C; the corrosion treatment time is generally 30 to 120 minutes, generally judged according to the depth of dissolution of the optical fiber cladding 62, that is, when the dissolution depth of the optical fiber cladding 62 reaches one-third of the thickness of the optical fiber cladding 62, then Corrosion treatment can be stopped.

Through the above treatment, although it can better suppress the phenomenon of fiber fusing, it cannot completely avoid the phenomenon of fiber fusing. Therefore, after the above treatment, the output power of the semiconductor laser 1 can be adjusted to gradually increase. If the fiber laser system works normally, If no abnormality occurs, it also shows that there is no fiber fusing; if sparks appear on the passive optical fiber 6 and propagate along the opposite direction of laser transmission at a very fast speed, it means that fiber fusing has occurred; as shown in Figure 3, when it occurs After the optical fiber is fused, the optical fiber core 61 can be observed through a microscope, and the optical fiber core 61 is impacted to form a bullet-shaped cavity.

Compared with the prior art, the present invention is based on a step-refractive-index fiber laser oscillator with an all-fiber structure, so its structure is simple, its safety and stability are high, and the thickness of the passive fiber is directly processed to reduce the fiber cladding. The thickness, which does not introduce other welding points, avoids additional loss, and its operation difficulty is low, the complexity is small, and it is beneficial to reduce the cost.

The specific embodiments of the present invention described above do not constitute a limitation to the protection scope of the present invention. Any other corresponding changes and modifications made according to the technical concept of the present invention shall be included in the protection scope of the claims of the present invention.

Claims (7)

1. a kind of based on the optical fiber fusing suppressing method for reducing fibre cladding thickness, it is used for the oscillation mode optical fiber of all -fiber mechanism Laser, it is characterised in that using the passive fiber in the oscillation mode optical fiber laser close to output terminal certain length as place Section is managed, removes the coat of processing section and the fibre cladding progress thickness of the processing section is handled to reduce the optical fiber of the processing section The thickness of covering.

It is 2. according to claim 1 based on the optical fiber fusing suppressing method for reducing fibre cladding thickness, it is characterised in that institute It is that the processing section is immersed hydrofluoric acid solution to carry out corrosion treatment to state thickness processing.

It is 3. according to claim 2 based on the optical fiber fusing suppressing method for reducing fibre cladding thickness, it is characterised in that institute The length for stating passive fiber is 0.5~1.5m.

It is 4. according to claim 3 based on the optical fiber fusing suppressing method for reducing fibre cladding thickness, it is characterised in that institute The length for stating processing section is 0.5~2.5mm.

It is 5. according to claim 4 based on the optical fiber fusing suppressing method for reducing fibre cladding thickness, it is characterised in that institute The concentration for stating hydrofluoric acid solution is 10~25%.

It is 6. according to claim 5 based on the optical fiber fusing suppressing method for reducing fibre cladding thickness, it is characterised in that institute The temperature for stating corrosion treatment is 15~25 DEG C.

It is 7. according to claim 6 based on the optical fiber fusing suppressing method for reducing fibre cladding thickness, it is characterised in that institute The time for stating corrosion treatment is 30~120 minutes.