KR20160114519A - Fiber laser device - Google Patents
Fiber laser device Download PDFInfo
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- KR20160114519A KR20160114519A KR1020160033822A KR20160033822A KR20160114519A KR 20160114519 A KR20160114519 A KR 20160114519A KR 1020160033822 A KR1020160033822 A KR 1020160033822A KR 20160033822 A KR20160033822 A KR 20160033822A KR 20160114519 A KR20160114519 A KR 20160114519A
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- wavelength
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- fiber
- optical amplifier
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
- H01S3/06—Construction or shape of active medium
- H01S3/063—Waveguide lasers, i.e. whereby the dimensions of the waveguide are of the order of the light wavelength
- H01S3/067—Fibre lasers
- H01S3/06754—Fibre amplifiers
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/09—Processes or apparatus for excitation, e.g. pumping
- H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
- H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
- H01S3/094042—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light of a fibre laser
- H01S3/094046—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light of a fibre laser of a Raman fibre laser
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/50—Amplifier structures not provided for in groups H01S5/02 - H01S5/30
- H01S5/509—Wavelength converting amplifier, e.g. signal gating with a second beam using gain saturation
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- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)
- Lasers (AREA)
- Optics & Photonics (AREA)
- Engineering & Computer Science (AREA)
- Plasma & Fusion (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
Abstract
A fiber laser apparatus comprising: a first optical amplifier for outputting light of a first wavelength; A first wavelength filter optically coupled to the first optical amplifier and transmitting light of the first wavelength and blocking light of wavelengths other than the first wavelength; A first Raman wavelength conversion unit optically coupled to the first wavelength filter to generate an inductive Raman scattering effect and to convert output light from the first wavelength filter into light having a second wavelength longer than the first wavelength; A second wavelength filter optically coupled to the first Raman wavelength converter and transmitting light of the second wavelength and blocking light of a wavelength other than the second wavelength; A second optical amplifier optically coupled to the second wavelength filter and amplifying output light from the second wavelength filter; A second Raman wavelength conversion unit optically coupled to the second optical amplifier to convert the output light from the second optical amplifier into light having a third wavelength longer than the second wavelength, And a third wavelength filter that is optically coupled to the second Raman wavelength conversion unit, transmits the third wavelength light, and blocks light having a wavelength other than the third wavelength.
Description
The present invention relates to a fiber laser device.
A fiber laser device having a pulse oscillator, a first wavelength filter, a wavelength converter, a second wavelength filter, and an optical fiber amplifier is disclosed in Patent Document 1 below.
In this fiber laser device, the pulse light output from the pulse oscillator passes through the first wavelength filter and enters the wavelength converter. The wavelength is converted into a wavelength within a gain wavelength band of the optical fiber amplifier so that the wavelength can be amplified to a desired output by a downstream optical fiber amplifier. The pulse light whose wavelength has been converted by the wavelength converter passes through the second wavelength filter. On the other hand, the pulse light whose wavelength has not been converted by the wavelength converter is blocked by the second wavelength filter. The pulse light transmitted through the second wavelength filter is amplified and output to a desired output by an optical fiber amplifier, and is used for laser processing or the like.
On the other hand, the reflected light from the surface to be processed is amplified by being transmitted through the optical fiber amplifier, becomes the high-intensity reflected light, and enters the second wavelength filter. Since the wavelength of the reflected light matches the wavelength of the output light incident on the optical fiber amplifier from the wavelength converter, the reflected light passes through the second wavelength filter and enters the wavelength converter. The reflected light transmitted through the wavelength converter is incident on the first wavelength filter, but the wavelength of the reflected light is blocked by the first wavelength filter because it differs from the wavelength of the original output light output from the pulse oscillator. In this manner, since the reflection light can be prevented from entering the pulse oscillator, it is possible to prevent the components in the pulse oscillator from being broken by the reflected light.
<Prior Art Literature>
- Patent Document 1: Japanese Patent No. 5198292
2. Description of the Related Art In recent years, the use of fiber laser devices has been diversified and a fiber laser device for outputting laser light on the longer wavelength side than the conventional one is sometimes required. However, there is a limitation in increasing the wavelength of light obtained by the optical fiber amplifier. Therefore, in the fiber laser device of Patent Document 1, there is a problem that laser light having a desired wavelength on the long wavelength side can not be obtained. Therefore, it is required to provide a fiber laser device capable of obtaining a laser beam having a desired wavelength on the long wavelength side while suppressing the influence of reflected light on a signal light generating portion such as a pulse oscillator.
An object of the present invention is to provide a fiber laser device capable of obtaining a laser beam having a desired wavelength on a longer wavelength side while suppressing the influence of reflected light on a signal light generating portion, .
According to an aspect of the present invention, there is provided a fiber laser apparatus including a first optical amplifier for outputting light of a first wavelength, a second optical amplifier optically coupled to the first optical amplifier, A first wavelength filter for blocking light having a wavelength other than the first wavelength; A first Raman wavelength conversion unit optically coupled to the first wavelength filter and expressing an induced Raman scattering effect and converting output light from the first wavelength filter into light having a second wavelength longer than the first wavelength; A second wavelength filter optically coupled to the first Raman wavelength converter and transmitting light of the second wavelength and blocking light of a wavelength other than the second wavelength; A second optical amplifier optically coupled to the second wavelength filter, the second optical amplifier amplifying output light from the second wavelength filter; A second Raman wavelength conversion unit optically coupled to the second optical amplifier to convert the output light from the second optical amplifier into light having a third wavelength longer than the second wavelength, And a third wavelength filter that is optically coupled to the second Raman wavelength conversion unit, transmits the third wavelength light, and blocks light having a wavelength other than the third wavelength.
The wavelength of the output light from the second optical amplifier is shifted to the long wavelength side and the light of the second wavelength is shifted to the second wavelength side by the third wavelength < RTI ID = 0.0 > As shown in FIG. Therefore, even if the second optical amplifier alone has a limitation on the long wavelength, output light with a longer wavelength can be obtained as compared with a conventional apparatus that does not include the second Raman wavelength converter.
On the other hand, when the reflected light of the third wavelength reflected from the irradiated object returns from the irradiated object, the light passes through the third wavelength filter and is incident on the second Raman wavelength converter. Here, the wavelength of the reflected light is also shifted to the long wavelength side, and the reflected light of the longer wavelength is incident on the second optical amplifier. The reflected light is amplified by the second optical amplifier, but the wavelength of the reflected light amplified by the second optical amplifier is longer than the third wavelength and is different from the wavelength (second wavelength) of the light converted by the first Raman wavelength converter Therefore, the reflected light amplified by the second optical amplifier can not pass through the second wavelength filter. Further, even if the second wavelength component is included in the reflected light and the second wavelength component can pass through the second wavelength filter, the second wavelength component can not pass through the first wavelength filter.
As described above, according to the fiber laser device of this embodiment, it is possible to obtain a desired output light having a longer wavelength, which can not be obtained only by the second optical amplifier, and at the same time, the influence of the reflected light on the first optical amplifier can be reliably suppressed.
The first Raman wavelength converter may include a first optical fiber, and the second Raman wavelength converter may comprise a second optical fiber.
In this case, the core diameter of the second optical fiber may be larger than the core diameter of the first optical fiber, and the length of the second optical fiber may be shorter than the length of the first optical fiber.
Wavelength conversion by inductive Raman scattering occurs when a strong incident light is incident to a nonlinear medium such that it exceeds a predetermined threshold value (Raman threshold value). Particularly, when the peak power density (= peak power / core cross section) of light is high and the fiber length is long, the wavelength conversion is more likely to occur. In the case of the above-described fiber laser device, since the incident light to the second Raman wavelength converter is amplified by the second optical amplifier, the peak power is larger than the incident light to the first Raman wavelength converter. Therefore, if the fiber length and the core cross-sectional area are the same, high-order unnecessary Raman scattering may occur in the second Raman wavelength converter. Therefore, according to the above arrangement, unnecessary high-order Raman scattering in the second Raman wavelength converter can be suppressed.
The second optical amplifier may include Yb doped fiber as the amplification fiber, and the wavelength of the light output from the second optical amplifier may be longer than 1060 nm.
When the reflected light of the third wavelength from the irradiated object returns from the irradiated object, it passes through the third wavelength filter and is incident on the second Raman wavelength converter. At this time, the reflected light passes through the second Raman wavelength converter, the wavelength of the reflected light further shifts to the long wavelength side, and the reflected light shifted to the longer wavelength enters the second optical amplifier. Here, the Yb doped fiber tends to have a lower gain as the gain peak is longer than 1060 nm at 1030 nm and 1060 nm. Therefore, when the wavelength of the output light from the second optical amplifier is longer than 1060 nm when the Yb doped fiber is used, the amplification of the reflected light returning from the second optical amplifier to the input side is suppressed and the influence of the reflected light to the first optical amplifier is further suppressed can do.
And the V value of the optical fiber reaching the output fiber from the input fiber to the second Raman wavelength converter is less than 2.4.
According to this configuration, since the output obtained from the fiber laser device is a single mode output, the beam quality is improved.
A polarization-maintaining fiber may be used at least in part and a single polarization may be output.
According to this configuration, it is possible to cope with a use in which a single polarized light is required as output light.
According to this aspect, it is possible to realize a fiber laser device capable of obtaining a laser beam having a desired wavelength on the longer wavelength side while suppressing the influence of reflected light on the signal light generating portion.
1 is a schematic configuration diagram of a fiber laser device according to a first embodiment.
2 is a diagram showing the wavelengths of respective lights after the output of the pulse oscillator, after the output of the first Raman wavelength converter, and after the output of the second Raman wavelength converter.
3A is a diagram showing the transmission characteristics of the first wavelength filter.
3B is a view showing the transmission characteristics of the second wavelength filter.
3C is a diagram showing transmission characteristics of the third wavelength filter.
4 is a schematic configuration diagram of a fiber laser device according to the second embodiment.
5 is a schematic configuration diagram of a modified example of the fiber laser device according to the second embodiment.
6 is a schematic configuration diagram of a modified example of the fiber laser device according to the second embodiment.
[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to Figs. 1 and 2. Fig.
The fiber laser device according to the present embodiment is an example of a pulsed fiber laser device preferable for use in applications such as laser processing. However, the application is not limited to laser processing.
Fig. 1 is a schematic configuration diagram of a fiber laser device according to the present embodiment.
1, the fiber laser device 1 includes a pulse oscillator (first optical amplifier) 2, a
2, the first wavelength? 1, which is the wavelength of the output light from the
The
The first wavelength filter (3) is optically coupled to the pulse oscillator (2). The
The first
The second wavelength filter (5) is optically coupled to the first Raman wavelength converter (4). The
The
The second
As a result, light of wavelength 1080 to 1100 nm is converted into light of wavelengths 1130 to 1150 nm by the second Raman
The
Table 1 summarizes the wavelength characteristics of the respective components described above.
Hereinafter, the operation of the fiber laser device 1 of the present embodiment will be described with reference to Table 1.
<Table 1>
First, attention is paid to output light. The light of the first wavelength? 1 (for example, 1030 nm) outputted from the
The light of the second wavelength? 2 output from the first Raman
Next, attention is paid to reflected light. The reflected light of the third wavelength? 3 from the surface to be processed passes through the
This reflected light is amplified by the
As described above, the fiber laser device 1 of the present embodiment is provided with the second Raman
In addition, the core diameter and fiber length of the optical fiber in each Raman wavelength conversion unit can be appropriately set for the purpose of, for example, adjustment of the optical power in which the inductive Raman scattering occurs. However, the core diameter of the optical fiber (second optical fiber) constituting the second Raman
Wavelength conversion by inductive Raman scattering occurs when a strong incident light is incident to a nonlinear medium such that it exceeds a predetermined threshold value (Raman threshold value). Particularly, when the peak power density (= peak power / core cross section) of light is high and the length of the fiber is long, the wavelength conversion is likely to occur relatively. Here, when A = peak power x (fiber length) / (cross-sectional area of core), when A exceeds a predetermined threshold value, Raman light of an arbitrary wavelength is generated. For example, let A 2 be the threshold at which the second Raman light is generated, A 3 be the threshold at which the third Raman light occurs, ... , let A be a threshold value at which n-th Raman light is generated, A2 <A3 <... <An.
In the case of the fiber laser device 1 according to the present embodiment, since the incident light to the second Raman
As in this embodiment, the wavelength of the output light from the
And the V value of the optical fiber reaching the output fiber from the input fiber to the second
[Second Embodiment]
Hereinafter, a second embodiment of the present invention will be described with reference to FIG.
The basic structure of the fiber laser device according to the second embodiment is the same as that of the fiber laser device of the first embodiment, except that it is a single polarized laser capable of obtaining a single polarized output, which is different from the first embodiment.
In FIG. 4, the same components as those in FIG. 1 used in the first embodiment are denoted by the same reference numerals, and a description thereof will be omitted.
4, the
In Fig. 4, the portion from the
The rest of the configuration is the same as that of the first embodiment.
It is possible to realize the
Although FIG. 4 shows an embodiment in which the
5, in the
As shown in Fig. 6, the
The technical scope of the present invention is not limited to the above embodiment, and various changes can be made within the scope of the present invention.
For example, in the embodiment described above, the first and second Raman wavelength conversion units are formed of optical fibers, but the first and second Raman wavelength conversion units are not necessarily composed of optical fibers. As the first and second Raman wavelength conversion units, for example, nonlinear optical crystals that exhibit an induced Raman scattering effect may be used.
In addition, specific configurations of each component of the fiber laser device, and oscillation wavelength, amplification wavelength, transmission wavelength and blocking wavelength of the wavelength filter, and the like are not limited to those of the above-described embodiments, but can be appropriately changed.
[Industrial applicability]
INDUSTRIAL APPLICABILITY The present invention can be used, for example, in a fiber laser apparatus used for material processing and the like.
1, 11, 21, 31 ... Fiber laser device, 2 ... A pulse oscillator (first optical amplifier), 3 ... A first wavelength filter, 4 ... A first
Claims (5)
A first wavelength filter optically coupled to the first optical amplifier and transmitting light of the first wavelength and blocking light of wavelengths other than the first wavelength;
A first Raman wavelength conversion unit optically coupled to the first wavelength filter and expressing an induced Raman scattering effect and converting output light from the first wavelength filter into light having a second wavelength longer than the first wavelength;
A second wavelength filter optically coupled to the first Raman wavelength converter and transmitting light of the second wavelength and blocking light of a wavelength other than the second wavelength;
A second optical amplifier optically coupled to the second wavelength filter and amplifying output light from the second wavelength filter;
A second Raman wavelength conversion unit optically coupled to the second optical amplifier to convert the output light from the second optical amplifier into light having a third wavelength longer than the second wavelength, And
A third wavelength filter optically coupled to the second Raman wavelength converter and transmitting light of the third wavelength and blocking light of wavelengths other than the third wavelength,
And a fiber laser.
Wherein the first Raman wavelength converter comprises a first optical fiber, the second Raman wavelength converter comprises a second optical fiber,
The core diameter of the second optical fiber is larger than the core diameter of the first optical fiber,
The length of the second optical fiber is shorter than the length of the first optical fiber,
Fiber laser devices.
Wherein the second optical amplifier comprises Yb doped fiber as an amplifying fiber,
The wavelength of the light output from the second optical amplifier is longer than 1060 nm,
Fiber laser devices.
The V-value of the optical fiber reaching from the input fiber to the output fiber to the second Raman wavelength converter is less than 2.4,
Fiber laser devices.
A polarization-maintaining fiber is used at least in part, and a single-
Fiber laser devices.
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JP2015060597A JP6140750B2 (en) | 2015-03-24 | 2015-03-24 | Fiber laser equipment |
JPJP-P-2015-060597 | 2015-03-24 |
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US6885683B1 (en) * | 2000-05-23 | 2005-04-26 | Imra America, Inc. | Modular, high energy, widely-tunable ultrafast fiber source |
JP2002006348A (en) * | 2000-06-21 | 2002-01-09 | Mitsubishi Electric Corp | Optical amplifier |
TWI231076B (en) * | 2003-04-29 | 2005-04-11 | Univ Nat Chiao Tung | Evanescent-field optical amplifiers and lasers |
TW200700871A (en) * | 2005-04-27 | 2007-01-01 | Nat Inst Japan Science & Technology Agency | Method for optical analog/digital conversion and device therefor |
TW200711238A (en) * | 2005-09-09 | 2007-03-16 | Univ Nat Chiao Tung | Adjustable optical fiber amplifier and laser using discrete fundamental-mode cutoff |
TW200737624A (en) * | 2006-03-28 | 2007-10-01 | Shen-Kuei Liaw | Laser source structure of optical laser pump |
CN101584093B (en) * | 2007-06-27 | 2011-11-23 | 株式会社藤仓 | Fiber laser having excellent reflected light resistance |
EP2381543B1 (en) * | 2008-12-26 | 2019-07-10 | Fujikura Ltd. | Fiber laser apparatus |
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JP5388204B2 (en) * | 2009-12-28 | 2014-01-15 | Kddi株式会社 | Communication apparatus and communication method |
JP5878165B2 (en) * | 2010-04-21 | 2016-03-08 | モビアス フォトニクス, インク. | Multi-wavelength Raman laser |
JP2012243789A (en) * | 2011-05-16 | 2012-12-10 | Miyachi Technos Corp | Fiber laser processing apparatus and laser processing method |
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TWI575827B (en) | 2017-03-21 |
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