CN115966992A - Fiber laser with sectional gain structure - Google Patents
Fiber laser with sectional gain structure Download PDFInfo
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- CN115966992A CN115966992A CN202310005566.2A CN202310005566A CN115966992A CN 115966992 A CN115966992 A CN 115966992A CN 202310005566 A CN202310005566 A CN 202310005566A CN 115966992 A CN115966992 A CN 115966992A
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- linear cavity
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- 239000000835 fiber Substances 0.000 title claims abstract description 52
- 239000013307 optical fiber Substances 0.000 claims abstract description 27
- 238000010521 absorption reaction Methods 0.000 claims abstract description 13
- 230000003321 amplification Effects 0.000 claims abstract description 8
- 238000005253 cladding Methods 0.000 claims abstract description 8
- 238000003199 nucleic acid amplification method Methods 0.000 claims abstract description 8
- 229910052769 Ytterbium Inorganic materials 0.000 claims abstract description 5
- 238000001914 filtration Methods 0.000 claims abstract description 5
- NAWDYIZEMPQZHO-UHFFFAOYSA-N ytterbium Chemical compound [Yb] NAWDYIZEMPQZHO-UHFFFAOYSA-N 0.000 claims abstract description 4
- 230000003287 optical effect Effects 0.000 claims description 27
- 101100456571 Mus musculus Med12 gene Proteins 0.000 claims description 13
- 238000005086 pumping Methods 0.000 claims description 9
- 238000000034 method Methods 0.000 claims description 4
- 230000010355 oscillation Effects 0.000 claims description 3
- 229910052761 rare earth metal Inorganic materials 0.000 description 5
- 150000002500 ions Chemical class 0.000 description 4
- 238000012423 maintenance Methods 0.000 description 4
- 238000012986 modification Methods 0.000 description 4
- 230000004048 modification Effects 0.000 description 4
- 230000005855 radiation Effects 0.000 description 4
- -1 rare earth ions Chemical class 0.000 description 4
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000010453 quartz Substances 0.000 description 2
- 150000002910 rare earth metals Chemical class 0.000 description 2
- 238000002310 reflectometry Methods 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 238000011161 development Methods 0.000 description 1
- 230000008713 feedback mechanism Effects 0.000 description 1
- 230000005283 ground state Effects 0.000 description 1
- 230000017525 heat dissipation Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A90/00—Technologies having an indirect contribution to adaptation to climate change
- Y02A90/10—Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation
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Abstract
The invention provides a fiber laser with a segmented gain structure, which comprises a high-reflection grating, a front-section gain fiber, a low-reflection grating, a rear-section gain fiber, a beam combiner and an output device QBH, wherein the high-reflection grating is connected with the front-section gain fiber; the Yb fiber doped with ytterbium of the original linear cavity is divided into two parts, the front half part is a linear cavity seed source part which comprises a high-reflection grating, a front-section gain fiber and a low-reflection grating and is used for generating seed laser with high beam quality; the second half part is an amplifier which comprises a rear section of gain fiber, a beam combiner and a QBH and is used for amplification, and the absorption coefficient is 15dB; the linear cavity seed source is of a linear cavity structure, residual pump light is absorbed by the linear cavity seed source, high beam quality is generated by the residual pump light, and optical fiber cladding light stripper CPS is not needed for cladding light filtering. The invention can output high beam quality continuous light by adopting a seed source and amplifier structure, can remove the CPS of the traditional linear cavity and reduce optical fiber devices.
Description
Technical Field
The invention relates to the technical field of laser, in particular to a fiber laser with a sectional gain structure.
Background
The optical fiber laser is a novel solid laser taking doped optical fiber as a laser medium, and has the advantages of good heat dissipation, high beam quality and the like.
As in conventional solid-state, gas lasers. The fiber laser basically consists of three basic elements, namely a pumping source, a gain medium and a resonant cavity. The pumping source generally adopts a high-power semiconductor Laser (LD), the gain medium is a doped fiber or a common nonlinear fiber, the resonant cavity can form various linear resonant cavities by optical feedback elements such as fiber gratings, the pumping light enters the gain fiber through coupling of a proper optical coupling system, the gain fiber forms population inversion after absorbing the pumping light, and stable laser output is finally formed after stimulated amplification and mode selection of the resonant cavity.
The gain medium is an optical fiber core doped with rare earth ions, and the doped optical fiber is clamped between the 2 reflectors, so that an F-P resonant cavity is formed.
Rare earth doped fiber amplifiers have facilitated the development of fiber lasers because fiber amplifiers can form fiber lasers through appropriate feedback mechanisms. When the pump light passes through the rare earth ions in the optical fiber, the pump light is absorbed by the rare earth ions. The rare earth atomic electrons absorbing photon energy can be excited to a higher lasing level, so that ion number inversion is realized, the inverted ion number can be transferred from the high level to a ground state in a radiation form, energy is released, and stimulated radiation is completed.
At present, two optical paths are adopted in a high-power continuous fiber laser, the first is an MOPA structure which realizes high-power continuous optical output by adopting a seed source and amplifier structure, and the second is a structure which adopts a grating as a resonant cavity for direct output. In the high-power continuous optical fiber laser, the quality of the output laser beam directly influences the use of the laser, the first beam quality is superior to that of the second mode, but the first mode is limited by a complex optical path structure and has high cost and poor later maintenance, and the high-power continuous optical output is realized by adopting the second mode in most of the conventional optical fiber lasers. That is, in the prior art, a linear cavity structure is mostly adopted for simplifying the optical path and facilitating maintenance in the later period, and the quality of the light beam is lower than that of the MOPA structure optical path.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides the optical fiber light path with the segmented structure, solves the defect of poor complex maintainability of the light path in the traditional MOPA structure, and can realize high-beam-quality and high-power continuous laser output of the MOPA structure under the condition that the number of devices is less than that of the devices in the traditional linear cavity.
The invention provides a fiber laser with a segmented gain structure, which comprises a high-reflection grating, a front-segment gain fiber, a low-reflection grating, a rear-segment gain fiber, a beam combiner and an output device QBH, wherein the high-reflection grating is arranged on the front-segment gain fiber;
the ytterbium-doped Yb optical fiber of the original linear cavity is divided into two parts, the front half part is a linear cavity seed source part which comprises a high-reflection grating, a front-section gain optical fiber and a low-reflection grating and is used for generating seed laser with high beam quality; the rear half part is an amplifier and comprises a rear section of gain optical fiber, a beam combiner and a QBH, the amplifier of the rear half part is used for amplifying, the absorption coefficient of the amplifier is 15dB, and residual pump light can enter the linear cavity seed source due to backward pumping of the amplifier;
the linear cavity seed source is of a linear cavity structure, the residual pump light is absorbed by the linear cavity seed source and can be used for generating high beam quality, and therefore an optical fiber cladding light stripper CPS is not needed for filtering cladding light.
Further, the linear seed source has a low absorption coefficient, but only needs to output low power due to the seed source + amplification optical path structure.
Further, the linear seed source used a 10m ytterbium-doped Yb fiber and the amplifier used a 20m ytterbium-doped Yb fiber.
The invention also provides an operation method of the optical fiber laser adopting the sectional type gain structure, which comprises the following steps: under the condition that the original linear cavity optical device is not changed, a seed source of the device and an amplified light path structure are recombined to form a high-power optical fiber laser with a master oscillation power amplification MOPA structure.
The method of the invention has the following advantages:
the invention can output high beam quality continuous light by adopting a seed source and amplifier structure based on the linear cavity device, and can remove CPS compared with the traditional linear cavity because the pumping light can be reasonably utilized, thereby reducing the optical fiber devices and facilitating later maintenance.
Drawings
FIG. 1 is a linear chamber optical path diagram;
FIG. 2 is a MOPA light path diagram;
fig. 3 is a segmented gain structure.
Detailed Description
Preferred embodiments of the present invention will be described in detail with reference to the following examples. It is to be understood that the following examples are given for illustrative purposes only and are not intended to limit the scope of the present invention. Numerous modifications and alternative arrangements may be devised by those skilled in the art without departing from the spirit and scope of the present invention and all such modifications and alternatives fall within the scope of the appended claims.
Beam quality refers to the output laser definition: measuring the degree of focus of a laser beam
The beam quality of a laser beam has a number of definitions, which are typically used to measure how well the laser beam is focused under certain conditions (e.g., limited beam divergence angle).
LD, laser diode semiconductor Laser;
MOPA, master OscillattorPower-Amplifier, amplifying the main oscillation power;
CPS, clasdingpower striper, fiber cladding Stripper;
QBH, quartz Block head, quartz output head;
absorption coefficient, absorption capacity of gain fiber to pump light, absorption coefficient
The laser absorption coefficient is usually 20dB or 99% in design;
the amplifier is designed with an absorption coefficient typically greater than 15dB, about 97%.
As shown in fig. 1, a linear cavity optical path forms an optical resonant cavity by a high reflective grating and a low reflective grating, pump light of an LD with a wavelength of 976nm or 915nm is combined by a beam combiner, ytterbium ions absorb energy to generate ion number inversion when the pump light enters the resonant cavity and passes through a gain fiber, upper level ions spontaneously radiate to generate laser, and the wavelength is selected by the resonant cavity to finally generate 1080nm laser of stimulated radiation. 3kW of continuous light is generated, and 7 kinds of optical fiber devices are required. Fewer devices, but poorer beam quality.
The MOPA optical path principle is shown in fig. 2, and a low-power seed optical amplifier structure is adopted to output high-power laser.
Taking the example of outputting 3kW laser, the optical power of the seed is 100W, the amplification factor of the amplifier is 30 times, and finally the 3kW laser is output. 3kW of continuous light is generated, and 11 optical fiber devices are required. The device is more, but the light beam is high in quality.
The invention designs a fiber laser with a segmented gain structure, as shown in figure 3, which generates 3kW continuous light and needs 6 fiber devices.
High reflecting grating: the reflectivity of the laser output wavelength is 99.9%, and the laser output wavelength and the low-reflection grating form an optical resonant cavity together.
Front-end gain fiber: the optical fiber is used as a gain fiber in a front-stage optical resonant cavity, and can form population inversion by utilizing residual pump light of a backward LD, and the population inversion and the high-low reflective grating jointly form the optical resonant cavity to provide seed light with high beam quality.
Low light reflecting grating: the reflectivity of the output laser wavelength is 10%, the laser and the high reflecting grating form an optical resonant cavity together, and the residual pump light can be utilized to generate laser of stimulated radiation.
Rear-end gain fiber: as a gain fiber in the amplifier, backward pump light was used to power-amplify the seed light to generate 3kW of high-power laser light.
A beam combiner: several hundreds of watts of LDs may be energy combined to provide sufficient pump power for the amplifier.
QBH: as the output device, the laser light can be output in any direction.
The devices are mature devices at present, and the invention just recombines the optical path on the basis of the devices to form an optical path structure similar to MOPA, and the structure is less than that of the traditional MOPA structure device.
The Yb fiber doped with ytterbium of the original linear cavity is divided into two parts, the front half part is a linear cavity seed source part which comprises a high-reflection grating, a front-section gain fiber and a low-reflection grating and is used for generating seed laser with high beam quality; the rear half part is an amplifier and comprises a rear gain optical fiber, a beam combiner and a QBH, the amplifier of the rear half part is used for amplifying, the absorption coefficient is about 15dB, the residual pump light of the backward pumping adopted by the amplifier can enter a seed source, the seed source is a linear cavity structure and can generate high beam quality by utilizing the residual pump light, and therefore CPS does not need to be adopted for cladding light filtering.
The absorption coefficient of the seed source part is low, but the seed source only needs to output lower power due to the adoption of a seed + amplification optical path structure, and the residual pumping light of the amplifier part is absorbed by the seed source, so that the filtering of the seed part is not needed to be increased.
The sectional gain structure is to combine the devices in the original linear cavity according to a new mode. By "segmented gain" is meant that the fiber in the original linear cavity is divided into 2 segments, one segment being used to generate seed laser light of high beam quality and the other segment being used for amplification. The structure with the seed source and the amplifier is the same as the structure principle of the traditional MOPA, but the light path is simplified, the sectional gain structure has few devices, and the system is stable and convenient for later maintenance.
The absorption coefficient of the gain fiber in the original linear cavity is 20dB, according to 30m 20/400 fiber estimation, a 10m ytterbium-doped Yb fiber is used as a seed source of the sectional gain structure, and a 20m ytterbium-doped Yb fiber is used as an amplifier, so that a light path of the sectional gain structure can be realized, and high-beam-quality laser output can be realized. The sectional gain structure has few devices and high light beam quality.
The invention provides a method for realizing a fiber laser with a segmented gain structure, which comprises the following steps:
under the condition that the original linear cavity optical device is not changed, the high-power optical fiber laser with the MOPA structure is formed by recombining the devices, and the new optical path structure is defined as a sectional type gain structure.
Although the invention has been described in detail above with reference to a general description and specific examples, it will be apparent to one skilled in the art that modifications or improvements may be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.
Claims (4)
1. A fiber laser with a segmented gain structure comprises a high-reflection grating, a front-section gain fiber, a low-reflection grating, a rear-section gain fiber, a beam combiner and an output device QBH;
the ytterbium-doped Yb optical fiber of the original linear cavity is divided into two parts, the front half part is a linear cavity seed source part which comprises a high-reflection grating, a front-section gain optical fiber and a low-reflection grating and is used for generating seed laser with high beam quality; the rear half part is an amplifier and comprises a rear section of gain optical fiber, a beam combiner and a QBH, the amplifier of the rear half part is used for amplifying, the absorption coefficient of the amplifier is 15dB, and residual pump light can enter the linear cavity seed source due to backward pumping of the amplifier;
the linear cavity seed source is of a linear cavity structure, the residual pump light is absorbed by the linear cavity seed source and can be used for generating high beam quality, and therefore an optical fiber cladding light stripper CPS is not needed for filtering cladding light.
2. The segmented gain structured fiber laser of claim 1, wherein the linear seed source has a low absorption coefficient but only needs to output low power due to the seed source + amplified optical path structure.
3. The segmented gain structured fiber laser of claim 1, wherein the linear seed source uses 10m ytterbium doped Yb fiber and the amplifier uses 20m ytterbium doped Yb fiber.
4. A method of operating a fibre laser employing a segmented gain structure as claimed in any one of claims 1 to 3, comprising: under the condition that an original linear cavity optical device is not changed, a seed source of the device and an amplified light path structure are recombined to form a high-power optical fiber laser with a master oscillation power amplification MOPA structure.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202310005566.2A CN115966992A (en) | 2023-01-04 | 2023-01-04 | Fiber laser with sectional gain structure |
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| CN202310005566.2A CN115966992A (en) | 2023-01-04 | 2023-01-04 | Fiber laser with sectional gain structure |
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| CN115966992A true CN115966992A (en) | 2023-04-14 |
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111244736A (en) * | 2020-01-16 | 2020-06-05 | 中国科学院西安光学精密机械研究所 | Seed amplification pump sharing MOPA fiber laser and laser generation method |
| CN113823990A (en) * | 2021-08-26 | 2021-12-21 | 南京理工大学 | Short-gain fiber oscillation amplification co-pumping high-power narrow linewidth laser |
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- 2023-01-04 CN CN202310005566.2A patent/CN115966992A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111244736A (en) * | 2020-01-16 | 2020-06-05 | 中国科学院西安光学精密机械研究所 | Seed amplification pump sharing MOPA fiber laser and laser generation method |
| CN113823990A (en) * | 2021-08-26 | 2021-12-21 | 南京理工大学 | Short-gain fiber oscillation amplification co-pumping high-power narrow linewidth laser |
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Application publication date: 20230414 |