Optically amplifying fiber, optically amplifying method, laser oscillating method, laser amplifier, laser oscillator, laser apparatus, and laser finishing machine

The present invention relates to an optical amplification method, an optical oscillation method, a laser device, and a laser processing machine using an optical amplification fiber to which a laser medium is added.

In recent years, laser processing has become widespread as one of the processing methods in the material processing field. For example, it has been recognized that laser welding and laser cutting have higher processing quality than other construction methods. The market is demanding higher quality and higher speed machining, and it produces high output, high efficiency, and better light collection, that is, single mode laser light with good beam quality (= high beam quality). We are looking for a laser oscillator or laser amplifier that emits light.

In a conventional laser oscillator, a fiber to which a laser medium is added and a fiber for transmitting excitation light are arranged in close proximity in order to achieve high output, and the space between them is filled with a substance having a predetermined refractive index (for example). See Patent Document 1 and Patent Document 2).

FIG. 8A shows the conventional laser oscillator, where 101 is an excitation optical amplifier fiber for transmitting excitation light, 102 is a laser optical amplifier fiber to which a laser medium is added, and the excitation optical amplifier fiber 101 and a laser. The optical amplifier fibers 102 are installed in close proximity to each other. Reference numeral 103 denotes a coupling chamber, which includes an excitation optical amplification fiber 101 and a laser optical amplification fiber 102, and is filled with a substance having a predetermined refractive index.

FIG. 8 (b) is a cross-sectional view taken along the line A-A'of FIG. 8 (a).

At both ends of the laser beam amplification fiber, a final stage mirror (not shown) that reflects the laser beam and an output mirror (not shown) that takes out a part of the laser beam and reflects the rest are arranged, whereby the laser beam is amplified by multiple feedback. Will be done.

The operation of the laser oscillator configured as described above will be described. The excitation light propagating through the excitation optical amplification fiber 101 enters the laser optical amplification fiber 102 in the coupling chamber 103 and excites the laser medium. Laser light is generated and emitted by the excitation and multiple feedback amplification.<patcit num="1"><text>JP-A-59-114883 (Fig. 1)</text></patcit><patcit num="2"><text>U.S. Pat. No. 4938561 (Fig. 1)</text></patcit>

<p> However, in a conventional laser oscillator, when trying to obtain a high output, the excitation source is a high-power semiconductor laser, and the diameter of the excitation optical amplification fiber 101 is increased to about 100 micrometers. Therefore, in order to efficiently inject the excitation light into the laser medium in order to increase the output, it is desirable that the diameter of the laser optical amplification fiber 102 is equal to or larger than the diameter of the excitation optical amplification fiber 101. Become. In that case, the beam quality deteriorates. On the other hand, in order to obtain laser light with good beam quality (= high beam quality), the diameter of the laser light amplification fiber 102 must be reduced. In the case of near-infrared laser light generally used for laser processing, the diameter of the laser light amplification fiber is about 6 to 10 micrometers in order to obtain a single-mode laser light with good beam quality. Therefore, the conventional laser oscillator has a problem that a laser beam having high output and high beam quality cannot be obtained.</p><p> An object of the present invention is to provide a compact, high-efficiency laser oscillator capable of obtaining high-power, high-beam quality laser light.</p>

<p> In order to solve the above problems, the laser oscillating device of the present invention guides the excitation light to the second waveguide, the first waveguide for transmitting the excitation light, the second waveguide for generating and transmitting the laser light, and the second waveguide for generating and transmitting the laser light. It has an optical amplification fiber structure with a third waveguide. Then, by combining this optical amplification fiber with an excitation source and a feedback means, a laser apparatus is provided in which excitation light is efficiently incident on a small-diameter excitation medium and efficiently emits high-output, high-beam quality laser light. can do.</p>

<p> As described above, the present invention comprises a first waveguide for transmitting excitation light, a second waveguide composed of a core to which a laser medium is added to generate laser light, and a cladding for transmitting the excitation light, and the first. It consists of a waveguide and a third waveguide including the second waveguide, the refractive index of the first waveguide is n1, the refractive index of the second waveguide clad is n2, and the refraction of the second waveguide core. Assuming that the rate is n3 and the refractive index of the third waveguide is n4, it is an optical amplification fiber in which n1 &lt;n4 &lt;n2 &lt;n3, and by using an excitation source and a feedback means, high output and high beam quality. It is possible to provide a laser device that emits various laser beams.</p>

(Embodiment 1) FIG. 1 (a) is an explanatory diagram of a laser oscillation method and a laser oscillator device using an optical amplifier fiber in the present embodiment 1, and FIG. 1 (b) is an explanatory view of A- of FIG. 1 (a). A'A cross-sectional view taken from the arrow.

In FIG. 1, 10a and 10b are semiconductor lasers that are excitation sources that generate excitation light, respectively, and 11a and 11b are lenses that are optical elements that guide the excitation light to the excitation optical waveguide, respectively. Reference numeral 20 denotes an optical amplifier fiber containing a laser medium as a part thereof, and the cross-sectional shape thereof is the same with respect to the laser light emission direction, that is, the optical axis direction.

The optical amplification fiber 20 is made of glass that transmits excitation light, and has a first waveguide 21 that is an excitation optical waveguide with a diameter of 125 micrometer and a D-shaped second guide that absorbs the excitation light and generates laser light. It is composed of a waveguide 22, a third waveguide 25 of a refractive index matching gel containing silicon as a main component for confining the excitation light, and an outer layer 26 of glass that encloses the refractive index matching gel to enhance the confinement efficiency of the excitation light.

The length of the optical amplification fiber 20 depends on the absorption coefficient of the laser beam determined by the concentration of the laser medium added to the core 23 and the like, the cross-sectional shape of the second waveguide 22, and the like, and is usually about 20 meters.

In addition, the second waveguide 22 has a core 23 having a diameter of 6 micrometer that transmits a single mode by adding neodium, which is a laser medium, and a diameter that is a glass base material that traps the laser light generated by excitation. Consists of 125 micrometer clad 24.

The refractive index of the first waveguide 21 is n1, the refractive index of the clad 24 of the second waveguide 22 is n2, the refractive index of the core 23 is n3, the refractive index of the third waveguide 25 is n4, and the refractive index of the outer layer 26 is n4. If n5, then n5 &lt;n1 &lt;n4 &lt;n2 &lt;n3.

Lenses 11a and 11b and semiconductor lasers 10a and 10b are arranged at both ends of the first waveguide 21, and excitation light is incident on the first waveguide 21, respectively.

On the other hand, at both ends of the core 23, a final stage mirror 12 that feeds back the laser light generated by the core 23 and an output mirror 13 that transmits a part of the laser light are provided so as to face each other.

The operation of the laser oscillator configured as described above will be described. The semiconductor laser 10 which is an excitation source emits a laser beam of 808 nanometers which is an excitation light of neodymium by a power source, a cooling device, and a control device (not shown). This excitation light is condensed to a predetermined numerical aperture (NA) by the lenses 11a and 11b, which are optical elements, and is incident and propagated from both ends of the first waveguide 21, which is an excitation optical waveguide that transmits the excitation light.

Comparing the refractive index n1 of the first waveguide 21 and the refractive index n4 of the third waveguide 25 surrounding the first waveguide 21, since n1 &lt;n4, the excitation light propagates through the first waveguide 21. , Enters the third waveguide 25.

When the refractive index n5 of the outer layer 26 and the refractive index n4 of the third waveguide 25 are compared, the excitation light incident on the third waveguide 25 is confined in the third waveguide 25 because n5 &lt;n4, and is confined to the third waveguide 25. Propagate while multiple reflections in the waveguide 25.

A part of the excitation light propagating in the third waveguide 25 is clad because the refractive index n2 of the clad 24 of the second waveguide 22 and the refractive index n4 of the third waveguide 25 are n2&gt; n4. It is incident on 24, confined in the second waveguide 22, and propagates through the second waveguide 22 while being multiple-reflected.

A part of the excitation light propagating in the second waveguide is incident on the core 23 because the refractive index n3 of the core 23 and the refractive index n2 of the clad 24 of the second waveguide 22 are n3&gt; n2. At that time, since the cross section of the clad 24 of the second waveguide 22 has a D-shaped shape, all of the clad 24 is absorbed by the core 23 while repeating multiple reflections in the clad 24 to excite neodium, which is a laser medium.

That is, the excitation light incident from both ends of the first waveguide 21 propagates while being attenuated in the second waveguide 22 by this absorption process, and is eventually absorbed by the neodymium in the core 23 to excite the neodymium. The light generated by excitation is a single-mode laser beam with a wavelength of 1064 nanometers, which is subjected to multiple amplification feedback and mode selection by the final stage mirror 12 provided at both ends of the core 23, the output mirror 13, and the core 23 that transmits single mode. Next, it emits from the output mirror 13.

In the first embodiment, the final stage mirror 12 and the output mirror 13 that feed back the laser beam may be FBG (fiber bragg grating) that can select the reflectance at the relevant wavelength or Frenel reflection on the fiber end face.

Further, in the first embodiment, a refractive index matching liquid containing glycerin as a main component may be used instead of the refractive index matching gel.

Further, in the first embodiment, the excitation light is incident from both ends of the first waveguide 21, but the excitation light may be incident only from one end.

Further, in the first embodiment, the optical amplification fiber 20 is configured and the first waveguide for transmitting the excitation light is one, but a plurality of the first waveguides may be used.

As described above, the optical amplification fiber 20 that includes the second waveguide 22 having a core for transmitting the single mode and the first waveguide 21 for transmitting the excitation light so that the excitation light can enter the core 23 is used. Therefore, it is possible to provide a laser oscillator that emits laser light having high output and high beam quality.

(Embodiment 2) In the second embodiment, the same configurations as those in the first embodiment are designated by the same numbers, and detailed description thereof will be omitted.

FIG. 2 (a) is an explanatory diagram of the laser oscillation method and the laser oscillation device using the optical amplification fiber according to the second embodiment, and FIG. 2 (b) is a cross section taken along the line A-A'of FIG. 2 (a). It is a figure.

The difference from the first embodiment is that the outer layer 29 is a horseshoe-shaped fluororesin, and the semiconductor laser 15 as an excitation source is connected to the semiconductor laser at one end by a fiber 16 and transmits excitation light at the other end. The point connected to the first waveguide, the point that the lenses 11a and 11b are not required, and the cross-sectional shape of the optical amplification fiber 28 in the direction perpendicular to the optical axis of the third waveguide 27 are D-type ultraviolet curable resins. There is a part thereof protruding from the outer layer 29, and in addition, the third waveguide 27 facing the curved portion of the second waveguide 22 is formed in a straight line.

The operation of the laser oscillator configured as described above will be described. In FIG. 2, the excitation light with a wavelength of 808 nanometers emitted by the semiconductor laser 15 with a fiber propagates through the fiber 16 and enters the first waveguide 21. As it propagates through the first waveguide 21, it enters the third waveguide 27. The refractive index n4 of the third waveguide 27, which the curved portion of the third waveguide 27 is in contact with, is larger than the refractive index of the outer layer 29 of the fluororesin, and the straight portion of the third waveguide 27 protruding from the outer layer 29 is Greater than the refractive index of the surrounding environment in contact.

Therefore, the excitation light is confined in the third waveguide 27 and propagates. At that time, since the cross section of the third waveguide 27 has a D-shaped shape, all of it is absorbed by the second waveguide 22 and excites neodymium while repeating multiple reflections in the third waveguide 27.

The light generated by excitation is multiplied by amplification feedback and mode selection by the final stage mirror 12 provided at both ends of the core 23, the output mirror 13, and the core 23 that transmits the single mode, and becomes single mode laser light from the output mirror 13. Exit.

In the second embodiment, the portion of the third waveguide 27 facing the curved portion of the second waveguide 22 is a straight line portion, but the arrangement thereof may be changed.

Further, in the second embodiment, the final stage mirror 12 and the output mirror 13 are provided at both ends of the second waveguide 22 to form a laser oscillator, but the final stage mirror 12 and the output mirror 13 are removed to perform laser amplification. A laser amplification device may be used as a laser amplification device in which seed light as a seed is incident from the end face of the second waveguide 22, amplified by the above excitation, and emitted from the other end of the second waveguide 32.

As described above, by using the optical amplification fiber 28 that includes the second waveguide 22 having a core for transmitting the single mode and the first waveguide 21 for transmitting the excitation light so that the excitation light can enter the core. It is possible to provide a laser oscillator that efficiently emits high-power, high-beam quality laser light.

(Embodiment 3) Fig. 3 (a) is an explanatory diagram of the optical amplification method and the laser amplification device using the optical amplification fiber according to the present embodiment 3, and FIG. 3 (b) is A of FIG. 3 (a). -A'arrow cross-sectional view, FIG. 3 (c) is a B-B' arrow-view cross-sectional view of FIG. 2 (a).

In FIG. 3, 14 is a semiconductor laser as an excitation source whose emitted laser light wavelength is 915 nanometers, and 11 is a lens which is an optical element that guides the excitation light to the excitation optical waveguide. Reference numeral 30 denotes an optical amplification fiber containing a laser medium as a part thereof, which is a glass that transmits excitation light. The first waveguide 31, which is an excitation optical waveguide with a diameter of 125 micrometer, absorbs the excitation light and emits the laser light. The second waveguide 32 having a D-shaped cross section in the direction perpendicular to the generated optical axis, the third waveguide 35 of the refractive index matching gel that traps the excitation light, and the refractive index matching gel are enclosed to confine the excitation light. Consists of an outer layer 36 of glass that enhances efficiency.

Further, the first waveguide 31 has a tapered shape in which the cross-sectional area gradually decreases in the direction of the optical axis. The second waveguide 32 has a 6-micrometer-diameter core 33 that transmits a single mode by adding itribium, which is a laser medium, and a 125-micron diameter glass base material that traps the laser light generated by excitation. Consists of metric clad 34.

The refractive index of the first waveguide 31 is n31, the refractive index of the clad 34 of the second waveguide 32 is n32, the refractive index of the core 33 is n33, the refractive index of the third waveguide 35 is n34, and the refractive index of the outer layer 36 is n34. If n35, then n35 &lt;n31 &lt;n34 &lt;n32 &lt;n33.

The operation of the laser amplification device configured as described above will be described. The semiconductor laser 14, which is an excitation source, emits a laser beam of 915 nanometers, which is the excitation light of itribium, by a power supply, a cooling device, and a control device (not shown). This excitation light is condensed to a predetermined numerical aperture (NA) by the lens 11 which is an optical element, and is incident and propagated from both ends of the first waveguide 31, which is an excitation optical waveguide that transmits the excitation light.

At this time, since the first waveguide 31 has a tapered shape in which the cross-sectional area in the direction perpendicular to the optical axis gradually decreases in the optical axis direction, the number of openings is larger than that of the columnar waveguide having the same cross section with respect to the laser optical axis. (NA) can be expected.

When the refractive index of the first waveguide 31 is n31 and compared with the refractive index n34 of the third waveguide 35 surrounding the first waveguide 31, the excitation light propagates through the first waveguide 31 because n31 &lt;n34. As a result, it enters the third waveguide 35. At that time, since the first waveguide 31 has a gradually decreasing tapered shape, the excitation light gradually increases the angle of incidence on the third waveguide 35 as it propagates through the first waveguide 31.

As a result, the excitation light is incident on the third waveguide 35 at a shorter distance in the direction of the laser optical axis as compared with the columnar waveguide having the same cross section with respect to the laser optical axis, and the refractive index n35 of the outer layer 36 and the th. Comparing with the refractive index n34 of 3 waveguide 35, since n35 &lt;n34, it is confined in the 3rd waveguide 35 and propagates while being multiple-reflected in the 3rd waveguide 35.

A part of the excitation light propagating in the third waveguide 35 is n32&gt; n34 when comparing the refractive index n32 of the clad 34 of the second waveguide 32 and the refractive index n34 of the third waveguide 35. It enters the clad 34, is confined in the second waveguide 32, and propagates through the second waveguide 32 while being multiple-reflected.

A part of the excitation light propagating in the second waveguide 32 is incident on the core 33 because the refractive index n33 of the core 33 and the refractive index n32 of the clad 34 of the second waveguide 32 are n33&gt; n32. To do. At that time, while repeating multiple reflections in the clad 34 of the second waveguide 32, all of them are absorbed by the core 33 and excite the itribium which is a laser medium. That is, the excitation light incident on the first waveguide 31 propagates while being attenuated in the second waveguide 32 by this absorption process, and is eventually absorbed by the itribium in the core 33 to excite the itribium. On the other hand, the seed light, which is the seed of laser amplification, is incident from the end face of the second waveguide 32. The incident seed light is amplified by the above excitation and emitted from the other end of the second waveguide 32.

In the third embodiment, the cross-sectional shape of the second waveguide is D-shaped, but it may be rectangular.

Further, as in the first embodiment, a refractive index matching liquid may be used instead of the refractive index matching gel.

As described above, the second waveguide 32 having a core for transmitting the single mode and the first waveguide 31 having a tapering taper shape in the optical axis direction for transmitting the excitation light are included so that the excitation light can enter the core. By using the optical amplification fiber 30, it is possible to provide a laser amplification device that emits laser light having high output and high beam quality.

(Embodiment 4) In the fourth embodiment, the same configurations as those in the third embodiment are designated by the same numbers, and detailed description thereof will be omitted.

FIG. 4 (a) is an explanatory view of the optical amplification method and the laser amplification device using the optical amplification fiber according to the fourth embodiment, and FIG. 4 (b) is a cross section taken along the line A-A'of FIG. 4 (a). In the figure, FIG. 4 (c) is a cross-sectional view taken along the line B-B'of FIG. 4 (a).

The difference from the third embodiment is that the first waveguide 31 is tilted in the direction of the laser optical axis and the shape of the third waveguide 45 changes accordingly, and similarly, the semiconductor laser 14 and the lens 11 is a point tilted with respect to the direction of the laser beam so that the excitation light enters from the front of the first waveguide 31.

In FIG. 4, the first waveguide 31 is tilted in the laser optical axis direction so that the minimum distance h between the first waveguide 31 and the second waveguide 32 is constant in the optical amplification fiber 40 in the laser optical axis direction. To do. Similarly, the semiconductor laser 14 and the lens 11 are tilted in the direction of the laser optical axis so that the excitation light is incident from the front of the first waveguide 31.

The operation of the laser oscillator configured as described above will be described. The excitation light emitted from the semiconductor laser 14 which is the excitation source propagates through the first waveguide 31 and then enters the third waveguide 45. At that time, the excitation light has a shape in which the cross-sectional area in the direction perpendicular to the optical axis of the first waveguide 31 gradually decreases in the optical axis direction, and the minimum distance from the second waveguide 32 is fixed. The angle from the waveguide 31 to the second waveguide 32 does not decrease as the excitation light propagates through the first waveguide 31, and is efficiently confined in the second waveguide 32 to excite itribium. On the other hand, the seed light, which is the seed of laser amplification, is incident from the end face of the second waveguide 32. The incident seed light is amplified by the excitation and emitted from the other end of the second waveguide 32.

In the present embodiment, the environment around the outer layer 36, that is, air, is used, but a layer having a refractive index smaller than the refractive index n35 of the outer layer 36, preferably a resin layer, may be provided.

As described above, a high-power, high-beam quality laser beam is provided by a fiber that includes a waveguide having a core that transmits a single mode and a tapering tapered waveguide that transmits excitation light so that the excitation light can enter the core. A laser amplification device that emits light can be provided.

(Embodiment 5) In the fifth embodiment, the same configurations as those in the second embodiment are designated by the same numbers, and detailed description thereof will be omitted.

FIG. 5 is an explanatory diagram of a laser oscillation method, an optical amplification method, and a laser apparatus using the optical amplification fiber according to the fifth embodiment.

The difference from the second embodiment is that the laser oscillator 51 of the second embodiment and the laser amplification devices 52 and 53 obtained by removing the final stage mirror 12 and the output mirror 13 from the laser oscillator 51 are multi-staged in series. Is.

The operation of the laser oscillator configured as described above will be described with reference to FIG. The excitation light with a wavelength of 808 nanometers emitted from the semiconductor laser 15 as an excitation source is incident on the optical amplification fiber 28 by the fiber 16 and has a wavelength of 1064 nanometers together with the final stage mirror 12 and the output mirror 13 as feedback means. Emit a laser beam. Next, this laser beam is incident on a second waveguide (not shown) in the optical amplification fiber 28b of the next stage. The incident laser light is amplified by the semiconductor laser 15b and is incident on a second waveguide (not shown) in the optical amplification fiber 28c of the next stage. The incident laser light is amplified by the semiconductor laser 15c and emitted.

In the fifth embodiment, the method in which the laser light emitted from the laser oscillator 51 is incident on the second waveguide of the optical amplification fiber 28b of the laser amplification device 52 in the next stage, and the laser amplification device 53 in the next stage. Although the method of incident on the second waveguide of the optical amplification fiber 28c of the above is not mentioned, spatial transmission using a lens or fiber transmission may be used. At that time, one end of the fiber 16b is connected to the laser oscillator 51 and the other end is connected to the laser amplification device 52, preferably fused, and one end of the fiber 16c is connected to the laser amplification device 52 and the other end to the laser amplification device 53. You may.

Further, the laser oscillator may be configured by using the second waveguide constituting the laser oscillator 51 and the laser amplifiers 52 and 53 in common. In addition, if the laser device of the fifth embodiment is mounted on the laser processing device and the emitted light is collected, processing such as welding and cutting can be performed, and the processing device can be used for production as a production facility.

As described above, laser oscillation using fibers 16, 16b, 16c including the second waveguide having a core for transmitting a single mode and the first waveguide for transmitting excitation light so that the excitation light can enter the core. By connecting the device 51 and the laser amplification devices 52 and 53 in series, it is possible to provide a laser device that emits laser light having high output and high beam quality.

(Embodiment 6) In the sixth embodiment, the same configurations as those of the first and second embodiments are assigned the same numbers and detailed description thereof will be omitted.

FIG. 6 (a) is an explanatory view of the laser oscillation method and the laser oscillator device using the optical amplifier fiber according to the sixth embodiment, and FIG. 6 (b) is a cross section taken along the line A-A'of FIG. 6 (a). It is a figure.

The difference from the first embodiment and the second embodiment is that the optical amplification fiber 60 includes four first waveguides 21 for transmitting excitation light, and arranges them so as to surround the second waveguide 62. , FBG (fiber Bragg grating) that reflects laser light at one end of the core 63 to which neodium, which is a laser medium that generates laser light, is added, and FBG (fiber) that transmits a part of laser light at the other end. Bragg grating) is provided.

The operation of the laser oscillator configured as described above will be described. In FIG. 6, each excitation light emitted by the semiconductor laser 15 with a fiber propagates through the fiber 16 and enters the first waveguide 21. As it propagates through the first waveguide 21, it enters the third waveguide 65. The incident light is absorbed by the second waveguide 62 and excites neodymium while repeating multiple reflections in the third waveguide 65. The light generated by the excitation is subjected to multiple amplification feedback and mode selection by the FBG provided at both ends of the core 63 and the core 63 that transmits the single mode, and becomes a single mode laser beam and is emitted from the end face of the optical amplification fiber 60.

In the sixth embodiment, the shapes and refractive indexes of the four first waveguides 21 are the same, but they may be different from each other. However, the refractive index of each of the four first waveguides 21 must be smaller than the refractive index n4 of the third waveguide 65. Also, the arrangement does not have to be equidistant with respect to the core 63.

As described above, the light including the second waveguide 62 having the core 63 for transmitting the single mode and the plurality of first waveguides 21 for transmitting the excitation light so that the respective excitation lights can be incident on the core 63 at the same time. It is possible to provide a laser oscillator that efficiently emits laser light with high output and high beam quality by using the amplification fiber 60.

(Embodiment 7) Fig. 7 (a) is an explanatory diagram of the laser oscillation method and the laser oscillator device using the optical amplifier fiber according to the present embodiment 7, and FIG. 7 (b) is A of FIG. 7 (a). -A'arrow cross-sectional view, FIG. 7 (c) is a B-B' arrow-view cross-sectional view of FIG. 7 (a).

In FIG. 7, 95a, 95b, and 95c are excitation sources that generate excitation light with a wavelength of 808 nanometers, respectively. Semiconductor lasers 77a, 77b, 77c transmit excitation light Excitation light transmission fibers 77d, 77e, 77f are excitation light. It is a transmission fiber core.

Reference numeral 70 denotes an optical amplification fiber of the seventh embodiment containing neodium, which is a laser medium, in the idle region 81a, 81b, 81c for transmitting excitation light in the longitudinal direction, and the excitation light for the laser medium. It is composed of injection regions 82a and 82b to be injected into the including waveguide.

The idle regions 81a, 81b, and 81c are excitation optical waveguides that transmit excitation light, and are the first waveguide composed of the excitation light transmission fiber core 71 of quartz glass, and the glass base material that absorbs the excitation light and generates laser light. The second optical wave guide 72, the third optical wave guide 75 of the ultraviolet curable resin that traps the excitation light, and the outer layer 76 of the glass that enhances the confinement efficiency of the excitation light are formed around it.

The injection regions 82a and 82b are composed of a second waveguide 72 that absorbs the excitation light and generates a laser beam, a third waveguide 75 that traps the excitation light, and an outer layer 76 that enhances the confinement efficiency.

Further, the second waveguide 72 is composed of a core 73 that transmits a single mode by adding neodymium, which is a laser medium, and a clad 74 of a glass base material that traps the laser beam generated by excitation.

The refractive index of the first waveguide 71 is n71, the refractive index of the clad 74 of the second waveguide 72 is n72, the refractive index of the core 73 is n73, the refractive index of the third waveguide 75 is n74, and the refractive index of the outer layer 76 is n74. If n75, then n75 &lt;n71 &lt;n74 &lt;n72 &lt;n73.

On the other hand, both ends of the core 73 have a highly reflective FBG78 that feeds back the laser light generated by the core 73 and a FBG79 that transmits a part of the laser light.

The excitation optical transmission fibers 77a, 77b, 77c penetrate the outer layer 76, and the excitation optical transmission fiber cores 77d, 77e, 77f are connected to the third waveguide 75.

Further, the excitation optical transmission fiber cores 77d, 77e, 77f are arranged at predetermined intervals, and the excitation optical transmission fiber core 77e and the excitation optical transmission fiber core 77f are opposed to each other.

The operation of the laser oscillator configured as described above will be described. Laser light with a wavelength of 808 nanometers emitted from the semiconductor laser 95a transmits the excitation light transmission fiber core 77a and the excitation light transmission fiber core 77d, and is incident on the third waveguide 75 in the idle region 81a of the optical amplification fiber 70. ..

The excitation light incident on the third waveguide 75 is incident on the injection region 82a of the optical amplification fiber 70, where the refractive index n75 of the outer layer 76 is compared with the refractive index n74 of the third waveguide 75, and n75 &lt;n74. Therefore, it is confined in the third waveguide 75 and propagates while being multiple-reflected in the third waveguide 75.

A part of the excitation light propagating in the third waveguide 75 is n72&gt; n74 when comparing the refractive index n72 of the clad 74 of the second waveguide 72 and the refractive index n74 of the third waveguide 75. It is incident on the clad 74, confined in the second waveguide 72, and propagates through the second waveguide 72 while being multiple-refracted.

A part of the excitation light propagating in the second waveguide 72 is n73&gt; n72 when comparing the refractive index n73 of the core 73 and the refractive index of the clad 74 of the second waveguide 72 with n72. Incident.

That is, the excitation light is all present in the third waveguide 75 in the idle region 81a, while it is present in the third waveguide 75 and the second waveguide 72 in the injection region 82a.

Similarly, laser light with a wavelength of 915 nanometers emitted from the semiconductor laser 95b transmits the excitation optical transmission fiber core 77b and the excitation optical transmission fiber core 77e, and the third waveguide 75 in the idle region 81b of the optical amplification fiber 70. Incident in.

The excitation light incident on the third waveguide 75 is incident on the injection region 82b of the optical amplification fiber 70, where the refractive index n75 of the outer layer 76 and the refractive index of the clad 74 of the second waveguide 72 are compared with n72. Since n75 &lt;n74, it is confined in the third waveguide 75 and propagates while being multiple reflected in the third waveguide 75.

A part of the excitation light propagating in the third waveguide 75 is n72&gt; n74 when comparing the refractive index n72 of the clad 74 of the second waveguide 72 and the refractive index n74 of the third waveguide 75. It is incident on the clad 74, confined in the second waveguide 72, and propagates through the second waveguide 72 while being multiple-refracted.

A part of the excitation light propagating in the second waveguide 72 is n73&gt; n72 when comparing the refractive index n73 of the core 73 and the refractive index of the clad 74 of the second waveguide 72 with n72. Incident.

That is, the excitation light is all present in the third waveguide 75 in the idle region 81b, while it is present in the third waveguide 75 and the second waveguide 72 in the injection region 82b.

Further, the laser light having a wavelength of 808 nanometers emitted from the semiconductor laser 95c transmits the excitation light transmission fiber core 77c and the excitation light transmission fiber core 77f, and enters the third waveguide 75 in the idle region 81c of the optical amplification fiber 70. Incident.

The excitation light incident on the third waveguide 75 is incident on the injection region 82b of the optical amplification fiber 70, where the refractive index n75 of the outer layer 76 is compared with the refractive index n74 of the third waveguide 75, where n75 &lt;n74. Therefore, it is confined in the third waveguide 75 and propagates while being multiple-refracted in the third waveguide 75.

A part of the excitation light propagating in the third waveguide 75 is n72&gt; n74 when comparing the refractive index n72 of the clad 74 of the second waveguide 72 and the refractive index n74 of the third waveguide 75. It is incident on the clad 74, confined in the second waveguide 72, and propagates through the second waveguide 72 while being multiple-refracted.

A part of the excitation light propagating in the second waveguide 72 is n73&gt; n72 when comparing the refractive index n73 of the core 73 and the refractive index of the clad 74 of the second waveguide 72 with n72. Incident.

That is, the excitation light is all present in the third waveguide 75 in the idle region 81c, while it is present in the third waveguide 75 and the second waveguide 72 in the injection region 82b.

From the above, each excitation light emitted from the semiconductor lasers 95a, 95b, and 95c enters the core 73 and excites the itribium added to the core 73. The light generated by excitation is subjected to multiple amplification feedback and mode selection by the highly reflected FBG78 that feeds back the laser light, the FBG79 that transmits some laser light, and the core 73 that transmits the single mode, which are provided at both ends of the core 73. , It becomes a single mode laser beam with a wavelength of 1064 nanometers and emits from the optical amplification fiber 70.

In the seventh embodiment, the laser beam is emitted from one end of the optical amplification fiber 70. However, by making the highly reflective FBG78 a partially transmissive type, the laser beam is emitted from both ends, and the laser beam is emitted from both ends. The output may be used as an output or a wavelength monitor.

In the seventh embodiment, the FBG is provided at the end of the optical amplification fiber, but the FBG is provided in the injection region, and the injection region is newly divided into three regions, an injection region, a free running region, and an injection region. Alternatively, the laser apparatus may be formed by a laser oscillation region composed of a pair of high-reflection FBG and transmission FBG, and another laser amplification region .

As described above, the second waveguide 72 having a core for transmitting a single mode and the first waveguide 71 for transmitting the excitation light are included so that the excitation light can be incident on the core by providing an idle region and an injection region. It is possible to provide a laser oscillating device that emits laser light having high output and high beam quality by the optical amplification fiber 70.

The optical amplification fiber, the optical amplification method, the optical oscillation method, the laser device, and the laser processing machine of the present invention are industrially useful as a laser device that emits a laser beam having high output and high beam quality.

<figref num="1">(a) Explanatory drawing of the laser oscillation method and the laser oscillation apparatus using the optical amplification fiber in the first embodiment of the present invention (b) A-A'cross-sectional view of FIG. 1 (a)</figref><figref num="2">(a) Explanatory drawing of the laser oscillation method and the laser oscillation apparatus using the optical amplification fiber in the second embodiment (b) A-A'cross-sectional view of FIG. 2 (a).</figref><figref num="3">(a) Explanatory drawing of the optical amplification method and the laser amplification apparatus using the optical amplification fiber in the third embodiment (b) A-A'arrow cross-sectional view of FIG. 3 (a) (c) FIG. 3 (a) B-B'arrow view cross section</figref><figref num="4">(a) Explanatory drawing of the optical amplification method and the laser amplification device using the optical amplification fiber according to the fourth embodiment (b) A-A'cross-sectional view of FIG. 4 (a) (c) FIG. 4 (a) ) B-B'arrow cross section</figref><figref num="5">Explanatory drawing of a laser oscillation method, an optical amplification method, and a laser apparatus using an optical amplification fiber in the fifth embodiment.</figref><figref num="6">(a) Explanatory drawing of the laser oscillation method and the laser oscillator apparatus using the optical amplification fiber in the sixth embodiment (b) A-A'cross-sectional view of FIG. 4 (a).</figref><figref num="7">(a) Explanatory drawing of the laser oscillation method and the laser oscillation device using the optical amplification fiber in the same embodiment (b) A-A'cross-sectional view of FIG. 7 (a) (c) FIG. 7 (a). B-B'arrow view cross section</figref><figref num="8">(a) Explanatory view of the conventional laser device (b) Cross-sectional view taken along the line A-A'in FIG. 8 (a)</figref>

Code description

10a, 10b Semiconductor laser 11, 11a, 11b Lens 12 Final stage mirror 13 Output mirror 14, 15, 15b, 15c Semiconductor laser 16, 16b, 16c Fiber 21, 31, 71 1st waveguide 22, 32, 62, 72th 2 waveguides 23, 33, 63, 73 cores 24, 34, 64, 74 clad 25, 27, 35, 45, 65, 75 3rd waveguide 28, 28b, 28c, 30, 40, 60, 70 Optical amplification fiber 51 Laser Oscillator 52, 53 Laser Amplifier 77a, 77b, 77c Excitation Optical Transmission Fiber 77d, 77e, 77f Excitation Optical Transmission Fiber Core 78 High Reflection FBG 79 Transmit FBG 81a, 81b, 81c Airborne Region 82a, 82b Injection Region