CN102255227A - Optical fiber cladding light filter and manufacturing method thereof - Google Patents

Abstract

An optical fiber cladding optical filter and a manufacturing method thereof. The structure of the optical fiber cladding optical filter is to remove a section of the coating layer of a single-clad optical fiber or a section of the coating layer and the outer cladding of a double-clad optical fiber. Use a cutting knife or chemicals to roughen the surface of the exposed cladding or inner cladding, destroying the total reflection conditions of the pump light and cladding laser in the cladding of single-clad fiber and the inner cladding of double-clad fiber. This section of optical fiber is sealed in a metal container with a water inlet and outlet, and the metal container is connected to flowing cooling water. The invention has simple structure, high filtering efficiency, can withstand higher power of filtered cladding light, can prevent thermal damage of the device, and can be used in high-power fiber lasers and high-power fiber amplifiers.

Description

Optical fiber cladding optical filter and manufacturing method thereof

technical field

The invention relates to a fiber laser and a fiber amplifier, in particular to a fiber cladding optical filter and a manufacturing method thereof.

Background technique

In high-power fiber lasers and fiber amplifiers, it is necessary to filter out the pump light and laser light in the cladding of the single-clad fiber or the inner cladding of the double-clad fiber before the final output to improve the final output light. beam quality. The existing technology is to remove a section of coating layer of single-clad optical fiber or a section of coating layer and outer cladding layer of double-clad optical fiber, and soak the exposed part in optical glue, because the refractive index ratio of optical glue requires The cladding or inner cladding to be filtered out has a high refractive index, so the pump light and laser in the cladding of a single-clad fiber or the inner cladding of a double-clad fiber will leak into the optical glue to achieve the filtering effect. Since the optical glue absorbs the pump light and laser to a certain extent, the conversion of light energy into heat energy will cause the temperature of the optical glue to rise beyond the threshold that the optical glue can withstand, thus limiting the optical fiber cladding optical filter. Power that can be filtered.

Contents of the invention

The object of the present invention is to overcome the above-mentioned problems in the prior art, provide an optical fiber cladding light filter and its manufacturing method, so as to increase the upper limit of the power that the cladding light filter can filter.

Technical solution principle of the present invention:

Remove a section of coating layer of single-clad optical fiber or a section of coating layer and outer cladding of double-clad optical fiber, so that the cladding of this exposed single-clad optical fiber or the inner cladding surface of double-clad optical fiber is covered with small The notch makes the incident angle of cladding light on the surface smaller than the critical angle of total reflection, destroying the condition of total reflection of cladding light. Moreover, the cladding light filtered out is incident on the cooling water and then irradiated on the wall of the metal container and converted into heat energy, which is taken away by the flowing cooling water, which overcomes the thermal effect caused by the use of high refractive index optical glue. In addition to the power limit.

Technical solution of the present invention is as follows:

An optical fiber cladding light filter is characterized in that it consists of an optical fiber to be filtered, a metal container and a water chiller, the side wall of the metal container has a water inlet and a water outlet, and each of the two ends has an optical fiber Through holes, the water supply port of the chiller is connected with the water inlet of the metal container, and the water return port of the chiller is connected with the water outlet of the metal container; the cladding light to be filtered unit The cladding optical fiber passes through the optical fiber through hole of the metal container, and the single-clad optical fiber coating layer of the cladding light to be filtered is stripped off a section of the optical fiber section that is exposed to the cladding and is full of gaps, or The coating layer of the double-clad optical fiber to be filtered out and the outer cladding stripped to expose a section of the optical fiber section full of gaps in the inner cladding are placed and sealed in the metal container.

The chiller controls the temperature of the cooling water between 15 and 30 degrees Celsius, and the flow of the cooling water in the metal container is greater than 1 liter/minute.

The cross-section of the cladding of the single-clad optical fiber to be filtered out or the inner cladding of the double-clad optical fiber to be filtered can be of any shape, and the core can be single-mode or is multimodal.

The preparation method of described optical fiber cladding optical filter comprises the steps:

① Strip off a section of the coating layer of the single-clad optical fiber to be filtered to expose the cladding, or strip a section of the coating and outer cladding of the double-clad optical fiber to be filtered to expose the cladding Inner cladding;

② Process the exposed cladding or inner cladding so that the surface is covered with notches and is called the notch cladding section of the optical fiber. The depth of the notch is greater than half of the width of the notch, and the depth and width of the notch are greater than the cladding The wavelength of light, the notch does not contact the core of the fiber;

③ passing the optical fiber of the cladding light to be filtered through the optical fiber through hole of the metal container, so that the notched cladding section of the optical fiber is placed and sealed in the metal container;

④ Connect the water supply port of the chiller to the water inlet of the metal container, and the water return port of the chiller to the water outlet of the metal container.

The length of the notch cladding section of the optical fiber is between 1 cm and 10 cm.

The sum of the flat areas between the notches on the notch cladding section of the optical fiber accounts for 10% to 90% of the total surface area.

The contact seal between the two ends of the optical fiber and the metal container should be located on the coating layer, and the entire notched surface should be sealed in the metal container, and the notched surface should not be in direct contact with the metal container.

Technical effect of the present invention:

Compared with the prior art, the present invention has simple structure, high filtering efficiency, can withstand higher power of filtering cladding light, can prevent thermal damage of devices, and can be used for high-power fiber lasers and high-power fiber amplifiers middle.

Description of drawings

Fig. 1 is a schematic structural view of the optical fiber cladding optical filter of the present invention.

Fig. 2 is a diagram of an embodiment of the fiber cladding optical filter of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the embodiments and accompanying drawings, but the protection scope of the present invention should not be limited thereby.

Please refer to Fig. 1, Fig. 1 is the structural representation of the optical fiber cladding light filter of the present invention, as shown in the figure, the optical fiber cladding light filter of the present invention is characterized in that it forms the optical fiber that comprises cladding light to be filtered , a metal container 6 and a water chiller 9, the side wall of the metal container 6 has a water inlet, a water outlet, and an optical fiber through hole 7 on both ends, the water supply port of the water chiller 9 is connected to the inlet of the metal container 6 The water outlet is connected, and the water return port of the chiller 9 is connected with the water outlet of the metal container 6; the single-clad optical fiber 1 to be filtered out of the cladding light passes through the optical fiber through hole 7 of the metal container 6, And strip the single-clad optical fiber coating layer 2 of the cladding light to be filtered out for a section of fiber section that is full of gaps to expose the cladding 3, or remove the double-clad optical fiber 1 of the cladding light to be filtered The coated layer and the outer cladding layer 2 are stripped to expose a section of the optical fiber section with the inner cladding layer 3 full of gaps and placed and sealed in the metal container 6 .

The chiller 9 controls the temperature of the cooling water between 15 and 30 degrees Celsius, and the flow of the cooling water in the metal container 6 is greater than 1 liter/minute.

The manufacturing method of described optical fiber cladding light filter, comprises the steps:

① Strip the coating 2 of the single-clad optical fiber 1 to be filtered to expose the cladding 3, or remove the coating and outer cladding 2 of the double-clad optical fiber 1 to filter the cladding light Peel off a section to expose the inner cladding 3;

② process the exposed cladding or inner cladding 3 so that the surface is covered with notches and is called the fiber notch cladding section 5, the depth of the notch is greater than 1/2 of the width of the notch, and the depth and width of the notch are greater than The wavelength of the cladding light, the gap is not in contact with the core 4 of the optical fiber;

③ passing the optical fiber to be filtered out of the cladding light through the optical fiber through hole 7 of the metal container 6, so that the notched cladding section 5 of the optical fiber is placed and sealed in the metal container 6;

④ Connect the water supply port of the chiller 9 with the water inlet of the metal container 6 , and connect the water return port of the chiller 9 with the water outlet of the metal container 6 .

The length of the notch cladding section of the optical fiber is between 1 cm and 10 cm.

The sum of the flat areas between the notches on the notch cladding section 5 of the optical fiber accounts for 10% to 90% of the total surface area.

Fig. 2 is the application example figure of fiber cladding optical filter of the present invention, as shown in the figure, the output optical fiber of kilowatt-level high-power all-fiberization laser 8 uses inner cladding 3 diameters to be the energy-transmitting optical fiber of 400 μ m as output optical fiber 1. Remove a section of coating 2 and outer cladding with a length of 6 cm on the output optical fiber, use a corrosive agent to corrode many small gaps on the surface of the exposed inner cladding 3, and then put this section of optical fiber notch cladding section 5 into the metal In the container 6, the two optical fiber through holes 7 are sealed. Connect the water inlet and the water outlet on the metal container to the water supply port and the water return port on the water cooler respectively, and pass through cooling water at 25°C with a flow rate of 2 liters/minute. An output collimation head 10 is installed at the end of the output optical fiber. About 200W of the pump light and cladding laser involved in the output fiber are filtered out, and the laser output from the collimation head is all distributed from the fiber core, and the beam quality is good, close to the diffraction limit. Experiments show that there is no overheating phenomenon in the optical fiber cladding optical filter. The optical fiber cladding light filter of the present invention has simple structure, high filtering efficiency, can withstand higher power of filtering cladding light, can prevent thermal damage of devices, and can be used for high-power fiber lasers and high-power fiber amplifiers middle.

Claims (5)

1. an optical fiber cladding light filter is characterized in that it constitutes an optical fiber, a metal container (6) and a chiller (9) comprising cladding light to be filtered out, and the side wall of the metal container (6) has The water inlet and the water outlet each have an optical fiber through hole (7) on both ends, the water supply port of the water chiller (9) is connected with the water inlet of the metal container (6), and the return of the water chiller (9) The water port is connected with the water outlet of the metal container (6); the single-clad optical fiber (1) of the described cladding light to be filtered passes through the optical fiber through hole (7) of the metal container (6), and Strip the single-clad optical fiber coating layer (2) of the cladding light to be filtered out to a section of the optical fiber section that is exposed to the cladding (3), or the double-clad optical fiber section of the cladding light to be filtered The coated layer and the outer cladding (2) of the layered optical fiber (1) are stripped, and a section of the optical fiber section that is exposed to the inner cladding (3) and covered with gaps is placed and sealed in the metal container (6). 2. The optical fiber cladding optical filter according to claim 1, characterized in that the temperature of the cooling water is controlled between 15 and 30 degrees Celsius by the chiller (9), and in the metal container (6) The flow rate of cooling water is greater than 1 liter/minute. 3. the manufacture method of optical fiber cladding optical filter according to claim 1 is characterized in that, the method comprises the steps: ① Strip the coating layer (2) of the single-clad optical fiber (1) to be filtered to expose the cladding (3), or remove the double-clad optical fiber (1) The coating layer and the outer cladding (2) strip off a section to expose the inner cladding (3); ② process the exposed cladding or inner cladding (3) so that the surface is covered with gaps, which are called optical fiber gap cladding sections (5), the depth of the gap is greater than 1/2 of the gap width, and the gap The depth and width are greater than the wavelength of the cladding light, and the gap is not in contact with the core (4) of the optical fiber; ③ Pass the optical fiber of cladding light to be filtered through the optical fiber through hole (7) of the metal container (6), so that the notch cladding section of the optical fiber (5) is placed and sealed in the metal container (6). Inside the container (6); ④ The water supply port of the chiller (9) is connected to the water inlet of the metal container (6), and the water return port of the chiller (9) is connected to the water outlet of the metal container (6). 4. The manufacturing method of the optical fiber cladding light filter according to claim 3, characterized in that, the length of the notch cladding section of the optical fiber is between 1 cm and 10 cm. 5. the manufacture method of optical fiber cladding light filter according to claim 3, is characterized in that, the summation of flat area between each breach on described optical fiber notch cladding section (5) accounts for this total surface area between 10% and 90%.

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