KR102432710B1 - Fiber laser monitoring system - Google Patents

Abstract

A high-power fiber laser monitoring system according to an embodiment comprises: a light source for outputting a laser beam; a first large-area optical fiber for guiding the laser beam generated from the light source to an output terminal; a second large-area optical fiber that installed to have at least part of the first large-area optical fiber coupled thereto and transmitting part of the laser beam passing the first large-area optical fiber; an optical fiber coupler for supporting coupling between the first large-area optical fiber and the second large-area optical fiber; a polarization measuring part including a polarization beam splitter connected to the second large-area optical fiber and a photodetector receiving the laser beam separated by the polarization beam splitter; and a control part for measuring the polarization state of the laser beam based on a result measured by the polarization measuring part. Therefore, the accuracy of measuring the performance of laser can be ensured.

Description

High Power Fiber Laser Monitoring System {FIBER LASER MONITORING SYSTEM}

The following description relates to a high power fiber laser monitoring system.

Fiber laser has high structural stability, excellent beam quality and output stability, and all-optical fiber laser made of optical fiber can be compact and lightweight. There is an increasing demand for increased output power and reduced size and weight of fiber lasers.

Research on increasing the output of fiber lasers is being actively conducted, and recently, several kW class single fiber lasers and several tens of kW class lasers combining multiple single fiber lasers have been reported. As fiber lasers of several kW or more and fiber laser-based tens of kW-class beam-combined lasers can be realized, the importance of monitoring the performance (output and polarization state) of high-power fiber lasers is increasing in terms of fiber laser applications and laser high output.

To check the laser output performance of kW or higher, an output meter with a water-cooled heat dissipation structure is required, and a chiller for cooling the output meter is required to operate the output meter.

In order to check the polarization state of the high-power fiber laser, an additional optical system or equipment is needed after the fiber laser, but the use of an additional optical system for checking the polarization state of the laser has a disadvantage in terms of compactness and weight reduction of the fiber laser.

On the other hand, even if polarization maintaining (PM) is used in kW-class high-power fiber lasers, it is necessary to monitor the polarization state. Therefore, polarization state monitoring is required, and an additional optical system is required for this.

The above-mentioned background art is possessed or acquired by the inventor in the process of derivation of the present invention, and cannot necessarily be said to be a known technology disclosed to the general public prior to the filing of the present invention.

It is an object of one embodiment to provide a high power fiber laser monitoring system.

A high-power fiber laser monitoring system according to an embodiment includes: a light source for outputting laser light; a first large-area optical fiber guiding the laser light generated from the light source to an output terminal; a second large-area optical fiber that is installed to couple at least a portion of the first large-area optical fiber and transmits a portion of the laser light passing through the first large-area optical fiber; an optical fiber coupler for supporting coupling between the first large-area optical fiber and the second large-area optical fiber; a polarization measuring unit including a polarization beam splitter connected to the second large-area optical fiber and a photodetector receiving laser light separated through the polarization beam splitter; and a control unit configured to measure a polarization state of the laser based on a result measured by the polarization measurement unit.

The optical fiber coupler may include: a coupler unit to which the first large-area optical fiber and the second large-area optical fiber are coupled; and a coupler fixing part fixedly accommodating the coupler part.

The coupler fixing unit may include: a lower housing having a groove inside which the coupler unit is accommodated; an upper housing covering an upper side of the lower housing; a first leaf spring interposed between the upper housing and the coupler part to provide an elastic force for pressing the coupler part into the housing; and a first fastening member fastened between the upper housing and the lower housing.

The high-power fiber laser monitoring system according to an embodiment may further include an optical fiber fixing unit configured to surround the first large-area optical fiber and the second large-area optical fiber connected to the optical fiber coupler.

The optical fiber fixing unit may include: a lower guide having a receiving groove in which the first large-area optical fiber or the second large-area optical fiber is accommodated; an upper guide covering an upper side of the lower guide; a cushioning material filled in the state in which the optical fiber is accommodated in the receiving groove; a second leaf spring interposed between the upper guide and the cushioning material to provide an elastic force for pressing the cushioning material into the lower guide; and a second fastening member fastened between the upper guide and the lower guide.

The optical fiber fixing unit is installed along a section of the first large-area optical fiber connected from the optical fiber coupler to the output end, and installed along a section of the second large-area optical fiber connected between the polarizing beam splitter from the optical fiber coupler. can be

The optical fiber fixing part may be formed of a rigid body integrally formed with the coupler fixing part.

The polarization measuring unit includes a first measuring unit and a second measuring unit respectively connected to both ends of the second large-area optical fiber passing through the optical fiber coupler, and each of the first measuring unit and the second measuring unit is the optical fiber coupler. a polarization beam splitter connected to the second large-area optical fiber connected from; and a photodetector receiving each of the two types of laser beams distributed from the polarizing beam splitter.

The polarization measuring unit may include: a variable optical attenuator connected to a second large-area optical fiber connected from the optical fiber coupler; and an interferometric optical coupler connected to each of the photodetector and the variable light attenuation unit, wherein the polarization measuring unit may have an interferometric structure.

According to the high-power optical fiber laser monitoring system according to an embodiment, it is possible to implement a high-power all-fiber optical fiber laser structure, and the laser output is directly measured compared to the laser output monitoring method using a non-contact measurement method, thereby measuring the accuracy of the laser performance. can be secured

When the large-area optical fiber-based optical coupler according to an embodiment is applied, an all-optical fiber laser configuration is possible, making it possible to reduce the size and weight compared to conventional lasers.

1 is a block diagram schematically showing the configuration of a high-power fiber laser monitoring system according to an embodiment.
2 is a plan view of a coupler fixing part and an optical fiber fixing part according to an embodiment.
3 is a cross-sectional view illustrating a configuration of an optical fiber fixing unit according to an embodiment.
4 is a cross-sectional view illustrating a configuration of a coupler fixing part according to an embodiment.
5 is a block diagram schematically illustrating the configuration of a high-power fiber laser monitoring system according to an embodiment.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. The following description is one of several aspects of the embodiments, and the following description forms part of the detailed description of the embodiments.

However, in describing an embodiment, a detailed description of a well-known function or configuration will be omitted in order to clarify the gist of the present invention.

In addition, the terms or words used in the present specification and claims should not be construed in a dictionary meaning, and the inventor may properly define the concept of the term in order to best describe his invention. Based on the principle that there is, it should be interpreted as a meaning and concept consistent with the technical idea of a high-power fiber laser monitoring system according to an embodiment.

Therefore, the embodiments described in this specification and the configurations shown in the drawings are only the most preferred embodiment of the high-power fiber laser monitoring system, and do not represent all the technical ideas of the fastening device according to the embodiment, so the present application It should be understood that there may be various equivalents and variations that may be substituted for them at any point in time.

1 is a block diagram schematically showing the configuration of a high-power fiber laser monitoring system according to an embodiment, FIG. 2 is a plan view of a coupler fixing part and an optical fiber fixing part according to an embodiment, and FIG. 3 is an embodiment FIG. 4 is a cross-sectional view showing the configuration of the optical fiber fixing part according to the embodiment.

1 to 4 , the high-power fiber laser monitoring system 1 according to an embodiment may monitor the output and polarization state of the high-power fiber laser in real time.

A high-power fiber laser monitoring system 1 according to an embodiment includes a light source 11 , a first large-area optical fiber 19a, an output terminal 15 , a polarization control unit 12 , an amplifier 13 , and an optical fiber coupler 14 . , a second large-area optical fiber 19b, an optical fiber fixing unit 16 , a polarization measuring unit 17 and a control unit 18 may be included.

The light source 11 can generate a laser beam. The light source 11 may be connected through the first large-area optical fiber 19a, so that the laser beam generated from the light source 11 may move along the first large-area optical fiber 19a.

The first large-area optical fiber 19a is installed between the light source 11 and the output terminal 15 to move the laser beam generated by the light source 11 to the output terminal 15 .

The second large-area optical fiber 19b may be coupled to the first large-area optical fiber 19a through the optical fiber coupler 14 to receive a portion of the laser beam propagating through the first large-area optical fiber 19a.

For example, the first large-area optical fiber 19a and the second large-area optical fiber 19b may have a diameter of 400 μm or more, unlike a general standard optical fiber having an outer diameter of about 125 μm.

For example, each of the first large-area optical fiber 19a and the second large-area optical fiber 19b includes a core 192 that is a central portion through which a laser beam passes, and a cladding surrounding the outer periphery of the core 192 ( 191 , and a coating 193 surrounding the outer surface of the cladding 191 may be included.

For example, the thickness of the core 192 of each of the first large-area optical fiber 19a and the second large-area optical fiber 19b may be between 20 μm and 30 μm, and the first large-area optical fiber 19a and the second large-area optical fiber 19a and The thickness of the cladding 191 of each of the two large-area optical fibers 19b may have a size between 250 μm and 400 μm.

The output terminal 15 may be connected from one end of the first large-area optical fiber 19a connected to the light source 11 to the other end opposite to that of the first large-area optical fiber 19a connected to the light source 11 .

The polarization control unit 12 is installed in the first large-area optical fiber 19a, and can adjust the polarization state of the laser beam passing through the first large-area optical fiber 19a through the control of the controller 18 .

For example, when the first large-area optical fiber 19a and the second large-area optical fiber 19b are polarization-maintaining fibers, the configuration of the polarization control unit 12 may be omitted.

The amplifier 13 may be an optical amplifier installed in the first large-area optical fiber 19a and capable of amplifying an optical signal of a laser beam passing through the first large-area optical fiber 19a.

For example, the amplifier 13 may include a preamplifier 131 installed at a position relatively first encountered with respect to the output direction of the laser beam, and a main amplifier 132 installed at a position following it. have.

The optical fiber coupler 14 may be installed at a portion where the first large-area optical fiber 19a and the second large-area optical fiber 19b are coupled.

For example, the optical fiber coupler 14 includes a coupler unit 142 to which the first large-area optical fiber 19a and the second large-area optical fiber 19b are coupled, and the coupler unit 142 fixedly accommodated and wrapped around the optical fiber coupler 14 . It may include a coupler fixing part 141 .

The coupler fixing part 141 may be a member of a housing type that supports the coupler part 142 in a surrounding form so that the coupler part 142 can be accommodated in a fixed position.

For example, the coupler fixing unit 141 includes a lower housing 1412 having a groove in which the coupler unit 142 is accommodated, an upper housing 1411 covering an upper side of the lower housing 1412 , and an upper portion. Between the first leaf spring 1413 interposed between the housing 1411 and the coupler part 142 to provide an elastic force for the coupler part 142 to be pressed into the housing, and the upper housing 1411 and the lower housing 1412 . It may include a first fastening member 1414 fastened to the.

For example, the lower housing 1412 may include a groove recessed from the upper side to accommodate the coupler unit 142 . For example, the shape of the groove of the lower housing 1412 may have a recessed shape to match the hexahedral coupler part 142 .

For example, as shown in FIG. 4 , the upper housing 1411 includes the first leaf spring 1413 so that the coupler part 142 is interposed in a state facing the coupler part 142 from the upper side. A groove in which a portion of the can be accommodated may be formed recessed from the lower side.

The first fastening member 1414 may be a member that connects and fixes the upper housing 1411 and the lower housing 1412 . For example, the first fastening member 1414 may be a fastening member such as screws, bolts, and nails.

As shown in FIG. 4 , the first leaf spring 1413 may have a plate-shaped structure in which the central portion is bent downward, and may press the coupler unit 142 through the downwardly protruding portion.

According to the coupler fixing unit 141, it is possible to minimize the change in polarization state due to external environmental factors such as physical movement or vibration in the process of the laser beam passing through the optical fiber coupler 14, thereby improving the reliability of the inspection. .

The optical fiber fixing unit 16 may be a housing for fixing the first large-area optical fiber 19a or the second large-area optical fiber 19b connected from the optical fiber coupler 14 so as to surround it. For example, the optical fiber fixing unit 16 may be fixedly connected to the coupler fixing unit 141 .

For example, the optical fiber fixing unit 16 may be installed along the section of the first large-area optical fiber 19a connected from the optical fiber coupler 14 to the output terminal 15 as shown in FIGS. , may be installed along a section of the second large-area optical fiber 19b connected between the optical fiber coupler 14 and the polarizing beam splitter 171 .

For example, the optical fiber fixing unit 16 includes a lower guide 162 having a receiving groove 1621 in which the first large-area optical fiber 19a or the second large-area optical fiber 19b is accommodated, and the lower guide. An upper guide 161 covering the upper side of the 162, a cushioning material 163 filled in a state in which a large-area optical fiber is accommodated in the receiving groove 1621, and a cover 165 installed on the upper surface of the cushioning material 163, A second leaf spring 166 interposed between the upper guide 161 and the cover 165 to provide an elastic force for pressing the cover 165 and the cushioning material 163 into the lower guide 162, and the upper guide 161 ) and a second fastening member 167 fastened between the lower guide 162 may be included.

For example, the lower guide 162 may include a receiving groove 1621 recessed from the upper side to accommodate the first large-area optical fiber 19a or the second large-area optical fiber 19b.

For example, as shown in FIG. 3, the lower portion of the receiving groove 1621 of the lower guide 162 has a cylindrical shape that is fitted to the outer circumferential surface of the first large-area optical fiber 19a or the second large-area optical fiber 19b. may be included, and through this, the first large-area optical fiber 19a or the second large-area optical fiber 19b can be molded to and closely adhered to the lower portion of the receiving groove 1621, so that it can be effectively fixed.

For example, as shown in FIG. 3 , the upper guide 161 may be interposed between the second leaf spring 166 and the cover 165 facing the cover 165 from the upper side. A groove in which a part can be accommodated may be recessed from the lower side.

The second fastening member 167 may be a member for connecting and fixing the upper guide 161 and the lower guide 162 . For example, the second fastening member 167 may be a fastening member such as screws, bolts, and nails.

The second leaf spring 166 may have a plate-shaped structure in which the central portion is bent downward as shown in FIG. 2 , and may be pressed against the cover 165 and the cushioning material 163 through the downwardly protruding portion. have.

According to the cover 165 , the elastic force of the second leaf spring 166 may be uniformly distributed and transmitted to the cushioning material 163 .

According to the optical fiber fixing unit 16 according to an embodiment, the optical fiber coupler 14 as a starting point between the first large-area optical fiber 19a and the second large-area optical fiber 19b are connected to subsequent optical components. Since each optical fiber can be fixed in the section, a change in the polarization state due to a change in the refractive index of each optical fiber 19 can be minimized.

According to the optical fiber fixing unit 16 according to an embodiment, it is possible to prevent physical damage to the optical fiber for transmission of a high-power laser of kW or higher due to external factors.

The polarization measuring unit 17 includes a polarization beam splitter 171 connected to a second large-area optical fiber 19b connected from the optical fiber coupler 14, and a laser beam separated through the polarization beam splitter 171. A photodetector 172 may be included.

For example, the polarization measuring unit 17 may be installed at each of the two ends of the second large-area optical fiber 19b connected to the optical fiber coupler 14, and in this case, along the first large-area optical fiber 19a Based on the direction in which the laser beam propagates toward the output end 15, the measuring unit connected to the second large-area optical fiber 19b input to the optical fiber coupler 14 may be referred to as a “first measuring unit 17a” and , a measuring unit connected to the second large-area optical fiber 19b output from the optical fiber coupler 14 may be referred to as a “second measuring unit 17b”.

For example, the photodetector 172 may be a photodiode that receives a bifurcated laser beam that is branched from the polarization beam splitter 171 .

For example, it should be noted that a configuration in which only one of the first and second measuring units 17a and 17b is installed is also possible.

The controller 18 may measure an output or a polarization state of the laser beam based on a value of an optical signal input to the photodetector 172 of the polarization measuring unit 17 .

For example, the control unit 18, based on the signal input to each of the photodetectors 172 branched from the polarization beam splitter 171 and connected, the laser polarization state at the position of the optical fiber coupler 14, and the output terminal ( 15), you can check the laser polarization state.

For example, as in the embodiment shown in FIG. 1 , the polarization measuring unit 17 is connected to both ends of the second large-area optical fiber 19b, respectively, of the first measuring unit 17a and the second measuring unit 17b. In the case of including the configuration, the control unit 18 measures the output of the laser beam by summing the values of the optical signals input to the photodetectors 172 of the first and second measuring units 17a and 17b, respectively. can

5 is a block diagram schematically illustrating the configuration of a high-power fiber laser monitoring system according to an embodiment.

The high-power fiber laser monitoring system 2 according to an embodiment includes a light source 21 , a first large-area optical fiber 29a, an output terminal 25 , a polarization control unit 22 , an amplifier 23 , and an optical fiber coupler 24 . , a second large-area optical fiber 29b, an optical fiber fixing unit 26, a polarization measuring unit 27 and a control unit 28 may be included.

For example, the optical fiber fixing part 26 may be installed along the section of the first large area optical fiber 29a connected from the optical fiber coupler 24 to the output end 25 as shown in FIG. 5, and the optical fiber coupler It may be installed along a section of the second large-area optical fiber 29b connected between the 24 and the polarizing beam splitter 271 .

The polarization measurement unit 27 includes a polarization beam splitter 271 connected from one end of the second large-area optical fiber 29b connected from the optical fiber coupler 24 and a polarization beam splitter 271 as shown in FIG. 5 . The output meter 273 measuring the output of the laser beam separated through It may include a variable light attenuation unit 274 connected to and connected to the interferometric optical coupler 275, a photodetector 272 and an interferometric optical coupler 275 connected to each of the variable light attenuation unit 274. .

As the interferometric structure can be formed by the structure of the optical fiber branched and connected to the polarizing beam splitter 271 and the variable light attenuator 274 through the interferometric optical coupler 275, the controller 28 controls the laser beam It becomes possible to measure the polarization state.

For example, the controller 28 may measure the output of the laser beam based on a signal measured by the output meter 273 , for example.

As described above, the embodiment has been described with reference to specific matters such as specific components and limited embodiments and drawings, but these are provided to help the overall understanding. In addition, the present invention is not limited to the above-described embodiments, and various modifications and variations are possible from these descriptions by those skilled in the art to which the present invention pertains. Therefore, the spirit of the present invention should not be limited to the above-described embodiments, and not only the claims to be described later, but also all those with equivalent or equivalent modifications to the claims will fall within the scope of the spirit of the present invention.

1,2 High power fiber laser monitoring system
11 light source
12 Polarization controller
13 amplifier
14 Fiber Optic Coupler
141 coupler fixing part
142 coupler part
15 output stage
16 Fiber optic fixture
17 Polarization measurement unit
171 Polarizing Beam Splitter
172 photodetector
18 control
19 Large Area Fiber Optic
191 1st large area optical fiber
192 second large area optical fiber

Claims (9)

a light source for outputting laser light;
a first large-area optical fiber guiding the laser light generated from the light source to an output terminal;
a second large-area optical fiber that is installed to couple at least a portion of the first large-area optical fiber and transmits a portion of the laser light passing through the first large-area optical fiber;
an optical fiber coupler for supporting coupling between the first large-area optical fiber and the second large-area optical fiber;
a polarization measuring unit including a polarization beam splitter connected to the second large-area optical fiber and a photodetector receiving laser light separated through the polarization beam splitter;
a control unit for measuring a polarization state of the laser based on a result measured by the polarization measuring unit; and
and an optical fiber fixing unit for fixing the first large-area optical fiber and the second large-area optical fiber connected to the optical fiber coupler to surround it;
The optical fiber coupler,
a coupler unit to which the first large-area optical fiber and the second large-area optical fiber are coupled; and
A high-power fiber laser monitoring system, including; a coupler fixing part fixedly accommodating the coupler part.
delete a light source for outputting laser light;
a first large-area optical fiber guiding the laser light generated from the light source to an output terminal;
a second large-area optical fiber that is installed to couple at least a portion of the first large-area optical fiber and transmits a portion of the laser light passing through the first large-area optical fiber;
an optical fiber coupler for supporting coupling between the first large-area optical fiber and the second large-area optical fiber;
a polarization measuring unit including a polarization beam splitter connected to the second large-area optical fiber and a photodetector receiving laser light separated through the polarization beam splitter; and
a control unit for measuring the polarization state of the laser based on the result measured by the polarization measuring unit;
The optical fiber coupler,
a coupler unit to which the first large-area optical fiber and the second large-area optical fiber are coupled; and
Including; a coupler fixing part for fixedly receiving the coupler part;
The coupler fixing part,
a lower housing having a groove in which the coupler unit is accommodated;
an upper housing covering an upper side of the lower housing;
a first leaf spring interposed between the upper housing and the coupler unit to provide an elastic force for pressing the coupler unit into the housing; and
and a first fastening member fastened between the upper housing and the lower housing.
delete The method of claim 1,
The optical fiber fixing unit,
a lower guide having a receiving groove inside which the first large-area optical fiber or the second large-area optical fiber is accommodated;
an upper guide covering an upper side of the lower guide;
a cushioning material filled with the optical fiber in the receiving groove;
a second leaf spring interposed between the upper guide and the cushioning material to provide an elastic force for pressing the cushioning material into the lower guide; and
A high-power fiber laser monitoring system comprising a; a second fastening member fastened between the upper guide and the lower guide.
6. The method of claim 5,
The optical fiber fixing unit,
High-power fiber laser installed along a section of the first large-area optical fiber connected from the optical fiber coupler to the output end, and installed along a section of the second large-area optical fiber connected from the optical fiber coupler to the polarizing beam splitter monitoring system.
6. The method of claim 5,
The high-power fiber laser monitoring system, characterized in that the optical fiber fixing part is formed of a rigid body integrally formed with the coupler fixing part.
6. The method of claim 5,
The polarization measuring unit,
and a first measuring unit and a second measuring unit respectively connected to both ends of the second large-area optical fiber passing through the optical fiber coupler,
Each of the first measurement unit and the second measurement unit,
a polarizing beam splitter connected to the second large-area optical fiber connected from the optical fiber coupler; and
A high-power fiber laser monitoring system including; a photodetector that receives the two types of laser beams distributed from the polarizing beam splitter, respectively.
6. The method of claim 5,
The polarization measuring unit,
a variable optical attenuator connected to a second large-area optical fiber connected from the optical fiber coupler; and
Further comprising; an interferometric optical coupler connected to each of the photodetector and the variable light attenuator;
The high-power fiber laser monitoring system, characterized in that the polarization measuring unit has an interferometric structure.

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