KR102333205B1 - Apparatus for Monitoring of Retro-reflection Light and Laser Beam Combiner including the same - Google Patents

Abstract

Disclosed are a reflected light monitoring device and a laser beam combiner including the same.
According to an embodiment of the present invention, a plurality of input optical fibers for irradiating a laser beam emitted from a fiber laser engine, the plurality of input optical fibers are arranged in an inner space formed in the center as the plurality of input optical fibers are combined in a predetermined shape, and the output unit It provides a laser beam combiner comprising a monitoring optical fiber for entering reflected light reflected back from the monitoring optical fiber and a reflected light monitoring device for receiving and monitoring the reflected light incident on the monitoring optical fiber.

Description

Apparatus for Monitoring of Retro-reflection Light and Laser Beam Combiner including the same

The present invention relates to a reflected light monitoring device capable of combining a high-power laser beam output from a fiber laser engine and monitoring the reflected output light, and a laser beam combiner including the same.

The content described in this section merely provides background information for the present embodiment and does not constitute the prior art.

Recently, processing technology using a laser has been developed in various industries, and accordingly, a fiber laser with excellent beam quality and excellent price competitiveness is in the spotlight. In particular, while the loss of the light source is small, the demand for a high-power fiber laser capable of obtaining a high output is increasing.

1 is a diagram showing the configuration of a conventional fiber laser.

The conventional fiber laser 100 includes a pump module 110 , a fiber laser engine 120 , and a laser beam combiner 130 .

The pump module 110 combines a signal beam and a plurality of pump beams into one and emits them to the fiber laser engine 120 . The signal beam and the plurality of pump beams are combined by a pump beam combiner (not shown), and the pump beam combiner may be configured in the form of the number of pump light sources (not shown) (n) × output (1).

The optical fiber laser engine 120 selectively amplifies the pump beam incident from the pump module 110 using an optical fiber Bragg grating (not shown) and a gain medium optical fiber (not shown), and then emits it to the laser beam combiner 130 . do. The fiber laser engine 120 may be configured in plurality, and has an output value of about 1 kW per unit fiber laser engine 120 .

The laser beam combiner 130 combines the laser beams output from the plurality of fiber laser engines 120 into one. As described above, since one fiber laser engine 120 has an output value of about 1 kW, when the fiber laser engine 120 is composed of three or more, the fiber laser 100 by the laser beam combiner 130 The output value of can be improved to 3kW or more. The structure of the laser beam combiner 130 will be described with reference to FIG. 2 .

2 is a view showing the structure of a conventional laser beam combiner.

The conventional laser beam combiner 130 includes a first input optical fiber 210 , a second input optical fiber 220 , and a third input optical fiber 230 .

The laser beam combiner 130 may be configured in the form of the number (n) × output (1) of the fiber laser engines 120 , and combines the laser beams output from the plurality of fiber laser engines 120 into one.

The first input optical fiber 210 , the second input optical fiber 220 , and the third input optical fiber 230 inject the laser beams output from the plurality of optical fiber laser engines 120 into the cores 212 , 222 , and 232 to external output as

In this way, the laser beam combiner 130 provides a laser beam of high power by combining the laser beams output from the plurality of fiber laser engines 120 .

Although the high-power fiber laser has a high output value, a phenomenon in which the output light returns to the input part of the fiber laser may occur due to unintentional retro-reflection. The output light reflected back in this way (hereinafter, abbreviated as 'reflected light') flows into the optical fiber amplifier or resonator in the optical fiber laser, thereby reducing the output amplification efficiency of the optical fiber laser system. Moreover, since the reflected light has a high peak output, when it enters the amplifier or resonator, it may damage the laser light source and the laser engine.

Moreover, the structure of the conventional laser beam combiner 130 has a limitation in that it cannot sense reflected light. In addition, when a separate monitoring device capable of detecting reflected light is attached to the laser beam combiner 130 and used, there is a problem in that the volume of the device increases.

On the other hand, since the light moving inside the fiber laser 100 has a wavelength in the infrared (IR) band, it is difficult to identify it with the naked eye. Accordingly, by changing the structure of the conventional laser beam combiner 130, it is required to develop a fiber laser capable of detecting reflected light and visually checking the movement of light moving inside the fiber laser.

An embodiment of the present invention has an object to provide a reflected light monitoring device for combining a laser beam output from a fiber laser engine into one, and a laser beam combiner including the same.

Another object of the present invention is to provide a reflected light monitoring device capable of preventing damage to a pump module or a fiber laser engine by reflected light, and a laser beam combiner including the same.

According to one aspect of the present invention, a plurality of input optical fibers for irradiating a laser beam emitted from a fiber laser engine, the plurality of input optical fibers are arranged in an inner space formed in the center as the plurality of input optical fibers are combined in a predetermined shape, and in the output unit It provides a laser beam combiner comprising a monitoring optical fiber for incident back-reflected light and a reflected light monitoring device for receiving and monitoring the reflected light incident on the monitoring optical fiber.

According to an aspect of the present invention, the monitoring optical fiber includes a core and a clad, and the reflected light reflected back from the output unit is incident on the core.

According to an aspect of the present invention, the reflected light monitoring device is characterized in that it is coupled to the monitoring optical fiber.

As described above, according to one aspect of the present invention, by combining the laser beams output from the fiber laser engine into one, there is an advantage in that it is possible to provide a high-power laser beam required for processing technology.

In addition, according to an aspect of the present invention, there is an advantage in that damage to the fiber laser can be prevented by monitoring the reflected light using a device connected to the laser beam combiner.

1 is a diagram showing the configuration of a conventional fiber laser.
2 is a view showing the structure of a conventional laser beam combiner.
3 is a diagram showing the configuration of a fiber laser according to an embodiment of the present invention.
4 is a stereoscopic view of a laser beam combiner according to an embodiment of the present invention.
5 is a cross-sectional view taken along line A-A' of FIG. 4 .
6 is a cross-sectional view taken along line BB′ of FIG. 4 .
7 is a cross-sectional view taken along line C-C' of FIG. 4 .
8 is a diagram illustrating a configuration of a reflected light monitoring apparatus according to an embodiment of the present invention.

Since the present invention can have various changes and can have various embodiments, specific embodiments are illustrated in the drawings and described in detail. However, this is not intended to limit the present invention to a specific embodiment, it should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention. In describing each figure, like reference numerals have been used for like elements.

Terms such as first, second, A, and B may be used to describe various elements, but the elements should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component. and/or includes a combination of a plurality of related listed items or any of a plurality of related listed items.

When a component is referred to as being “connected” or “connected” to another component, it is understood that the other component may be directly connected or connected to the other component, but other components may exist in between. it should be On the other hand, when it is said that a certain element is "directly connected" or "directly connected" to another element, it should be understood that no other element is present in the middle.

The terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. It should be understood that terms such as “comprise” or “have” in the present application do not preclude the possibility of addition or existence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification in advance. .

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and should not be interpreted in an ideal or excessively formal meaning unless explicitly defined in the present application. does not

3 is a diagram showing the configuration of a fiber laser according to an embodiment of the present invention.

The fiber laser 300 according to an embodiment of the present invention includes a pump module 310 , a fiber laser engine 320 , a laser beam combiner 330 , and a reflected light monitoring device 340 .

The pump module 310 includes a signal light source 312 , a pump light source 314 , a connecting optical fiber (not shown) and a pump beam combiner 316 .

The pump module 310 oscillates a signal beam and a pump beam using a plurality of light emitting devices. The oscillated signal beam and pump beam are transmitted to a connecting optical fiber, and are combined by a pump beam combiner 316 .

The signal light source 312 oscillates a signal beam and makes it incident on the fiber laser engine 320 . The signal light source 312 may be implemented as a laser diode, which is a semiconductor light emitting device, but is not limited thereto.

The pump light source 314 oscillates the pump beam and transmits it to the connecting optical fiber. The pump light source 314 may be implemented in the form of a plurality of laser diodes, but is not limited thereto. Pump beams oscillated from a plurality of laser diodes are combined by a pump beam combiner 316 and are incident on a fiber laser engine 320 .

The pump beam combiner 316 combines the signal beam and the plurality of pump beams generated from the signal light source 312 and the pump light source 314 . Typically, the pump beam coupler 316 may be configured of an optical fiber, and the optical fiber is configured in the form of the number of pump light sources 314 (n)×output (1).

The fiber laser engine 320 includes a fiber Bragg grating FBG 322 and a gain medium optical fiber 324 .

The fiber laser engine 320 injects the pump beam combined into one by the pump beam combiner 316 . The fiber laser engine 320 amplifies the incident pump beam and transmits it to the laser beam combiner 330 . The fiber laser engine 320 may have an output value of about 1 kW and may be configured in plurality.

The optical fiber Bragg grating 322 is a refractive index change pattern formed in the optical fiber core, and selectively reflects or transmits only a specific wavelength of the pump beam. The pump beam amplified by the fiber Bragg grating 322 is coupled or absorbed at the fiber core.

The gain medium optical fiber 324 is a gain medium of the pump light source 314 and may include a structure for selectively amplifying only a specific wavelength of the pump beam generated by the pump light source 314 . The gain medium optical fiber 324 is coupled to the output end of the pump beam combiner 316 and includes a core (not shown) and a cladding (not shown). The gain medium optical fiber 324 may be an active optical fiber including a core made of a silica material to which a rare earth is added, but is not limited thereto.

The laser beam combiner 330 combines the laser beams output from the plurality of fiber laser engines 320 into one, and oscillates a high-power laser beam to the outside. At the same time, the laser beam combiner 330 transmits the reflected light incident to the laser beam combiner 330 to the reflected light monitoring device 340 .

More specifically, the laser beam combiner 330 receives the laser beam output from the fiber laser engine 320 and injects an input optical fiber (not shown) and reflected light that irradiates or transmits the laser beam to the outside and the reflected light monitoring device 340 . It includes a monitoring optical fiber (not shown) that outputs to. The laser beam combiner 330 may be configured in the form of the number (n) of the number of fiber laser engines 320 + the monitoring optical fiber (1), but the shape may be changed according to the number (n) of the fiber laser engines 320 . have. A detailed description of the structure of the laser beam combiner 330 will be described later with reference to FIGS. 4 to 7 .

The reflected light monitoring device 340 analyzes the information of the reflected light output from the monitoring optical fiber, generates a warning sound or a warning light, or cuts off the power supply of the optical fiber laser 300 , and thereby the pump module 310 or the optical fiber laser engine 320 . ) not to be damaged by reflected light. The reflected light monitoring device 340 is connected to the end of the monitoring optical fiber of the laser beam combiner 330 , and the configuration of the reflected light monitoring device 340 will be described in detail with reference to FIG. 8 .

4 is a three-dimensional view of a laser beam combiner according to an embodiment of the present invention, FIG. 5 is a cross-sectional view taken along line A-A' of FIG. 4, and FIG. 6 is a cross-sectional view taken along line B-B' of FIG. And FIG. 7 is a cross-sectional view taken along line C-C' of FIG. 4 .

As shown in FIG. 4 , the laser beam combiner 330 according to an embodiment of the present invention includes an input unit 410 , a splicing unit 420 , and an output unit 430 .

The laser beam combiner 330 may be implemented in the form of a heterogeneous optical fiber. As the laser beam combiner 330 is implemented in the form of a heterogeneous optical fiber, the structures of the input unit 410 and the output unit 430 of the laser beam combiner 330 are different.

The input unit 410 guides the laser beam output from the fiber laser engine 320 and transmits it to the output unit 430 . In addition, as will be described later with reference to FIG. 5 , the input unit 410 includes the monitoring optical fiber 540 to output reflected light to the reflected light monitoring device 340 .

The outside of the input unit 410 is surrounded and protected by the capillary tube 415 . The capillary tube 415 may be made of a thermoplastic plastic, but is not limited thereto.

The rear end of the input unit 410 is implemented in a bundle shape by a tapering process, and is coupled to the front end of the output unit 430 by a splicing unit 420 .

Furthermore, although not shown in the drawings, the laser beam combiner 330 may include a temperature sensor (not shown) at the rear end of the input unit 410 . Since the laser beam coupler 330 includes a temperature sensor, it is possible to detect overheating caused by the laser beam. The laser beam combiner 330 is provided with a separate temperature monitoring device (not shown) connected to the temperature sensor, so that the fiber laser 300 is not damaged by heat.

Referring to FIG. 5 , the input unit 410 includes a first input optical fiber 510 , a second input optical fiber 520 , a third input optical fiber 530 , and a monitoring optical fiber 540 .

As described above, the input unit 410 receives the laser beams output from the plurality of fiber laser engines 320 and transmits the received laser beams to the output unit 430 . The outer diameter of the cross section of A-A' of the input unit 410 may be configured to be around 860 μm, and the inner diameter may be configured to be around 500 μm, but is not limited thereto.

The first to third input optical fibers 510 , 520 , and 530 include cores 512 , 522 , 532 and clads 514 , 524 , 534 , and transmit the laser beam output from the optical fiber laser engine 320 , respectively. It is incident on the cores 512 , 522 , and 532 , and guides it to the output unit 430 .

The output light (reflected light) reflected back from the output unit 430 of the laser beam combiner 330 may be introduced into the laser beam combiner 330 again. At this time, the reflected light is incident on the core (not shown) of the monitoring optical fiber 540 of the input unit 410 along the core 710 of the output unit 430 of the laser beam combiner 330 . More specifically, the reflected light is mainly focused and incident on the core portion of each optical fiber constituting the laser beam combiner 330 . The laser beam combiner 330 receives the reflected light and transmits the reflected light to the reflected light monitoring device 540, using the monitoring optical fiber 540 disposed in the space formed in the center of the input optical fibers 510, 520, and 530 to reflect the reflected light. get hired And the monitoring optical fiber 540 outputs the incident reflected light to the reflected light monitoring device 340 connected to the terminal. The monitoring optical fiber 540 outputs the reflected light to the reflected light monitoring device 340 , so that the reflected light is not further introduced into the optical fiber laser 300 .

The monitoring optical fiber 540 may be disposed in a space of about 80 μm formed in the center according to the shape in which the first input optical fiber 510, the second input optical fiber 520, and the third input optical fiber 530 are typically disposed. have. The monitoring optical fiber 540 includes a core (not shown) and a clad (not shown), and extends in the opposite direction from which the laser beam is output from the laser beam combiner 330, and has a reflected light monitoring device 340 at the end. is combined

In one embodiment of the present invention, the number of input optical fibers 510, 520, and 530 constituting the input unit 410 is shown as three, but the number of input optical fibers 510, 520, and 530 is the number of fiber laser engines 320 ( Depending on n), four or six may be implemented. Even if the number (n) of the fiber laser engines 320 is different, since a space is formed inside the disposed fiber laser engines 320 , the monitoring optical fiber 540 may be disposed in the formed internal space.

As shown in FIG. 6, the rear end of the input unit 410 by tapering is bundled with a first input optical fiber 510, a second input optical fiber 520, a third input optical fiber 530, and a monitoring optical fiber 540. It is composed in the form of a bundle). The outer diameter of the input unit 410 bundled by tapering may be implemented in a range of 160 to 170 µm and an inner diameter of 100 µm, but is not limited thereto. Although the input unit 410 is tapered to reduce the size of the outer and inner diameters compared to the tip, the first input optical fiber 510, the second input optical fiber 520, the third input optical fiber 530, and the monitoring optical fiber 540 The shape of the core and clad of the is maintained without distortion.

Referring back to FIG. 4 , the output unit 430 combines the laser beam guided from the input unit 410 and outputs it to the outside. As the output unit 430 combines a plurality of laser beams, the fiber laser 300 according to an embodiment of the present invention oscillates a high-power laser beam. The front end of the output unit 430 is connected to the rear end of the input unit 410 by the splicing unit 420 . A more detailed structure of the output unit 430 will be described later with reference to FIG. 7 .

As shown in FIG. 7 , the output unit 430 includes a core 710 and a clad 720 .

As described above, the output unit combines the laser beam guided by the input unit 410 to oscillate a high-power laser beam to the outside. The laser beam guided by the input unit 410 is mainly incident on the core 710 of the output unit 410 , and the laser beam moving along the core 710 is output to the outside. At this time, a part (reflected light) of the output laser beam is reflected back and returned to the core 710 of the output unit 430 , and the reflected light follows the core 710 of the output unit 430 and the input unit 410 is monitored. It is incident to the optical fiber 540 .

8 is a diagram illustrating a configuration of a reflected light monitoring apparatus according to an embodiment of the present invention.

Referring to FIG. 8 , the reflected light monitoring device 340 includes an integrating sphere 810 , a photodetector 820 , an ADC converter 830 , a controller 840 , a display 850 , a storage 860 , and an alarm output. part 870 .

The integrating sphere 810 is connected to the end of the monitoring optical fiber 540, and diffusely reflects the reflected light into a uniform luminous intensity. Since the inside of the integrating sphere 810 is coated with a material having a high reflectance, the reflected light is continuously diffusely reflected within the integrating sphere 810 . As the reflected light is continuously diffusely reflected, the intensity and optical characteristics of the reflected light are averaged and output to the photodetector 820 . Accordingly, damage to the photodetector 820 by the reflected light having a high output is prevented.

Meanwhile, the integrating sphere 810 may be replaced with a thermal sensing type optical power sensor (not shown). In this case, the reflected light monitoring device 340 may be implemented in such a way that the light detection unit 820 is directly connected to the monitoring optical fiber 540 .

The photodetector 820 is coupled to one side of the integrating sphere 810 , converts the light uniformly distributed by the integrating sphere 810 into a current, and outputs the value to the ADC converter 830 .

The ADC converter 830 converts the analog signal of the current output from the photodetector 820 into a digital signal and transmits it to the controller 840 .

The controller 840 analyzes the analog signal of the current received from the ADC converter 830 and controls each component of the reflected light monitoring device 340 to generate a warning light or a warning sound.

The control unit 840 controls the operation of the display unit 850 by calculating the power value of the reflected light based on the digital signal received from the ADC converter 830 . That is, the control unit 840 digitizes the calculated power value of the reflected light so that it can be displayed on the display unit 850 .

The control unit 840 receives the digital signal from the ADC converter 830 and controls the operation of the alarm output unit 870 . The control unit 840 compares and analyzes the data recorded in the storage unit 860 and controls the alarm output unit 870 to generate a warning light or a warning sound when the signal received from the ADC converter 830 is above a preset level. .

Furthermore, when the signal received from the ADC converter 830 is higher than a preset level compared to the data recorded in the storage unit 860, the control unit 840 is configured to turn off the power supply to the optical fiber laser 300 . Control the supply unit (not shown).

The display unit 850 displays the power value of the reflected light digitized under the control of the control unit 840 using the display device. As the display unit 850 displays the power of the reflected light as a numerical value, the power value of the reflected light flowing into the pump module 310 or the fiber laser engine 320 may be grasped.

The storage unit 860 stores the amount of current of the reflected light as a digital signal and provides it to the control unit 840 by converting it into a database.

The alarm output unit 870 generates a warning light or a warning sound so that the user can recognize by the control unit 840 when the amount of current of the reflected light is equal to or greater than a preset level under the control of the control unit 840 .

The above description is merely illustrative of the technical idea of this embodiment, and various modifications and variations will be possible by those skilled in the art to which this embodiment belongs without departing from the essential characteristics of the present embodiment. Accordingly, the present embodiments are intended to explain rather than limit the technical spirit of the present embodiment, and the scope of the technical spirit of the present embodiment is not limited by these embodiments. The protection scope of this embodiment should be interpreted by the following claims, and all technical ideas within the equivalent range should be interpreted as being included in the scope of the present embodiment.

100: conventional fiber laser
110: pump module
120: fiber laser engine
130: laser beam combiner
210, 510: first input optical fiber
220, 520: second input optical fiber
230, 530: third input optical fiber
300: fiber laser
310: pump module
320: fiber laser engine
330: laser beam combiner
340: reflected light monitoring device
410: input of the laser beam combiner
415: capillary tube
420: splicing unit
430: output unit
540: monitoring optical fiber
710: output core
720: output clad
810: integrating sphere
820: light detection unit
830: ADC converter
840: control unit
850: display unit
860: storage
870: alarm output unit

Claims (3)

an input unit receiving and guiding the laser beam emitted from the fiber laser engine; and
It includes a core and a clad, and includes an output unit for receiving the laser beam guided from the input unit into its core and outputting it to the outside,
The input unit,
a plurality of input optical fibers each including a core and a clad, the plurality of input optical fibers receiving the laser beam emitted from the optical fiber laser engine into each core and transmitting the laser beam to the output unit; and
It includes a core and a clad, and is disposed in an inner space formed in the center as the plurality of input optical fibers are disposed adjacent to each other, and a part of the laser beam output from the output unit is reflected back to the core of the output unit. Accordingly, it receives the reflected light reflected back to the input unit to its core, and includes a monitoring optical fiber that makes the incident reflected light incident to the reflected light monitoring device,
The rear end of the input unit is implemented in a bundle shape by a tapering process, coupled to the front end of the output unit by a splicing unit, and coupled to the rear end of the input unit by the splicing unit The output unit combines a plurality of laser beams guided from the input unit and outputs them to the outside,
The monitoring optical fiber extends in the opposite direction from which the laser beam is output from the laser beam coupler, and the reflected light monitoring device is coupled to the end thereof,
The reflected light monitoring device is connected to the end of the monitoring optical fiber, and analyzes information on the reflected light output from the monitoring optical fiber to generate a warning or cut off the power supply.
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