JP6738218B2 - Optical device and laser device - Google Patents

Description

The present invention relates to an optical device and a laser device including the optical device.

The fiber laser device is used in various fields such as a laser processing field and a medical field because it is excellent in light condensing property, has a high power density, and can obtain a light having a small beam spot.

The fiber laser device propagates a high-power laser beam emitted from an oscillator to an optical fiber, and emits the laser beam via a quartz block connected to the emission end of the optical fiber. Since the quartz block is provided for the purpose of reducing the energy density of laser light emitted from the optical fiber, it generally has a larger outer diameter than the cladding diameter of the optical fiber. The structure on the emission end side of the laser light in such a fiber laser device is disclosed in, for example, Patent Document 1 below. Hereinafter, the surface of the quartz block on the side to which the output end of the optical fiber is connected is referred to as the incident surface, and the surface on the opposite side may be referred to as the output surface.

Japanese Patent No. 5243273

The light that enters the quartz block from the optical fiber is emitted from the emission surface of the quartz block, is condensed by passing through a machining head having a condenser lens, and is irradiated onto the object to be machined. The light applied to the object to be processed becomes heat by being absorbed by the object to be processed, and contributes to the processing. However, a part of the light emitted to the object to be processed may be reflected on the surface of the object to be processed, and a part of the reflected light may return to the quartz block. The light emitted from the quartz block and returning to the quartz block in this manner may be hereinafter referred to as return light. Further, the light output from the oscillator and propagating to the exit surface side of the quartz block may be referred to as signal light below.

When the light emitted from the quartz block and ideally collected at the processing point is vertically incident on the surface of the object to be processed and reflected vertically, the return light is condensed by the processing head and It is re-coupled to the core of the optical fiber connected to the quartz block on the incident surface side. In this way, when the return light is recombined with the core of the optical fiber, it is easy to detect the intensity of the return light.Therefore, measures such as safely stopping the emission of the laser light are taken, which causes a problem. It is easy to prevent from happening.

However, in reality, ideal focusing is difficult due to the aberration of the lens of the processing head and the thermal lens effect. In addition, fine irregularities and slopes are generally formed on the surface of the object to be processed. Therefore, the return light may enter the periphery of the core of the optical fiber on the incident surface of the quartz block, for example, the clad of the optical fiber or the portion to which the optical fiber is connected. Thus, when the return light enters around the core of the optical fiber on the incident surface side of the quartz block, the quartz block and the optical fiber are heated, which may cause a problem such as deterioration of the characteristics of the laser device.

Therefore, it is an object of the present invention to provide an optical device capable of suppressing heating of a quartz block or an optical fiber by return light, and a laser device including the optical device.

The optical device of the present invention includes a quartz block having an incident surface and an emitting surface facing the incident surface, a light emitting core connected to the incident surface for propagating light incident on the quartz block, and the incident surface. Among them, at least one photodetection core connected to the periphery of the connection portion with the light emission core, and a detector for detecting the intensity of light emitted from the photodetection core, To do.

Further, a laser device of the present invention is characterized by including the above optical device and at least one light source that emits light propagating through the light emitting core.

The light propagating through the light emitting core enters the quartz block and exits from the emitting surface of the quartz block. Part of the light emitted from the emission surface may be return light returning to the quartz block as described above. In the above optical device, the photodetection core is connected to the periphery of the connection part with the light emission core on the incidence surface of the quartz block, so that the connection part with the light emission core on the incidence surface of the quartz block is connected. The return light that is incident on the surroundings can be incident on the photodetection core. Further, by providing a detector capable of detecting the intensity of the light emitted from the light detection core, the intensity of the return light incident on the light detection core can be indirectly detected as described above. That is, it is possible to detect the intensity of the returning light that is incident on the periphery of the connection portion with the light emitting core on the incident surface of the quartz block. Therefore, measures can be taken before the quartz block or the optical fiber is excessively heated by the returning light, and the quartz block or the optical fiber can be prevented from being heated by the returning light.

Further, at least in a portion connected to the quartz block, the light emitting core and the light detecting core are integrally surrounded by a glass body having a lower refractive index than the light emitting core and the light detecting core. Is preferred.

By integrating the light emitting core and the light detecting core as described above, the glass body between the light emitting core and the light detecting core is provided in addition to the returning light directly incident on the light detecting core. A part of the incident return light can also be incident on the photodetection core through the glass body. Therefore, it becomes easy to detect the return light incident on the periphery of the connection portion with the light emitting core on the incident surface of the quartz block. Further, by integrating the light emitting core and the light detecting core as described above, the light emitting core and the light detecting core are maintained while maintaining the relative positional relationship between the light emitting core and the light detecting core. It becomes easy to connect the core for use to a predetermined position of the quartz block.

Further, the glass body has a high refractive index portion that surrounds the light emitting core, and a low refractive index portion that has a lower refractive index than the high refractive index portion and that surrounds the high refractive index portion. It is preferable that the detection core is surrounded by the low refractive index portion.

Since the glass body surrounding the light emitting core has the high refractive index portion and the low refractive index portion as described above, even if light leaks from the light emitting core, the light has a low refractive index from the high refractive index portion. It is difficult to enter the rate section. Therefore, by surrounding the photodetection core with the low refractive index portion, it is possible to prevent the light propagating through the light emission core from leaking and entering the photodetection core, and to prevent erroneous detection of return light. it can.

Further, it is preferable that a reflecting portion is provided inside or at an end of the light detecting core, and the detector detects the intensity of the light reflected by the reflecting portion.

By thus providing the light detecting core with the reflecting portion, it is possible to cause the light detecting core to emit the return light and detect the return light with the detector with a simple configuration.

Further, it is preferable that the light emitting core and the light detecting core are separated from each other on the side opposite to the side connected to the quartz block.

Since the light emitting core and the light detecting core are separated, the light detecting core can be bent, and the return light propagating through the light detecting core can be guided to a desired place and detected by the detector. You can Therefore, the degree of freedom in designing the optical device can be improved.

Further, a plurality of the photodetection cores are provided, and the plurality of photodetection cores are arranged at equal intervals on a circle centered on the central axis of the light emission core, at least in a portion connected to the quartz block. It is preferably arranged.

By providing a plurality of photodetection cores in this way, it is easy to cause the return light to enter the photodetection core regardless of which direction the return light is incident on the light exit core.

Further, it is preferable that a plurality of the light detection cores and the plurality of the detectors are respectively provided, and the plurality of the detectors individually detect the intensities of light emitted from the plurality of the light detection cores.

By individually detecting the intensities of the light emitted from the plurality of light detection cores in this manner, it is easy to determine in which direction the return light is incident on the light emission core. Therefore, for example, it becomes easy to determine in which direction the workpiece should be tilted to make it difficult for the returning light to enter the quartz block. As a result, it becomes easier to take appropriate measures before the return light excessively heats the quartz block or the optical fiber, and it becomes easier to further suppress the heating of the quartz block or the optical fiber by the return light.

Further, it is preferable that the diameter of the light detecting core is larger than the diameter of the light emitting core.

The diameter of the light emitting core is limited to some extent by the wavelength of the signal light propagating through the light emitting core. On the other hand, the larger the diameter of the photodetection core, the easier it is for the return light to enter the photodetection core. Therefore, by making the diameter of the light detection core larger than the diameter of the light emission core, it becomes easier for the return light to be incident on the light detection core, and the return light incident at a position displaced from the light emission core can be detected. It will be easier. As a result, it becomes easier to suppress heating of the quartz block and the optical fiber by the returning light.

Further, it is preferable that the refractive index of the light detecting core is higher than that of the quartz block.

Since the refractive index of the photodetection core is higher than that of the quartz block, reflection of return light at the interface between the photodetection core and the quartz block is suppressed, and the return light is easily incident on the photodetection core. Become. Therefore, it becomes easier to detect the return light that enters at a position displaced from the light emitting core, and it becomes easier to suppress the heating of the quartz block or the optical fiber by the return light.

As described above, according to the present invention, an optical device capable of suppressing heating of a quartz block or an optical fiber by return light and a laser apparatus including the optical device are provided.

It is a conceptual diagram which shows the laser apparatus which concerns on 1st Embodiment of this invention. It is sectional drawing which shows a part of optical device shown in FIG. 1 schematically. FIG. 3 is a diagram schematically showing a cross section taken along line III-III of the optical device shown in FIG. 2. It is a figure which expands and shows a part of optical device shown in FIG. It is a graph which shows the relationship between the angle of the processed surface with respect to output light, and the ratio of return light with respect to output light. It is sectional drawing which shows some optical devices which concern on 2nd Embodiment of this invention roughly. FIG. 7 is a diagram schematically showing a cross section taken along line VII-VII of the optical device shown in FIG. 6. It is a figure which shows roughly the one part cross section of the optical device which concerns on other embodiment.

Hereinafter, preferred embodiments of an optical device and a laser apparatus according to the present invention will be described in detail with reference to the drawings.

(First embodiment)
<Laser device>
First, the configuration of the laser device according to the first embodiment of the present invention will be described.

FIG. 1 is a conceptual diagram showing a laser device 1 according to the first embodiment of the present invention. As shown in FIG. 1, the laser device 1 of the present embodiment includes a plurality of light sources 10, an optical combiner 20, and an optical device 30 as main components.

Each light source 10 is a laser device that emits light of a predetermined wavelength, and is, for example, a fiber laser device or a solid-state laser device. When the light source 10 is a fiber laser device, it may be a resonator type fiber laser device or a MO-PA (Master Oscillator Power Amplifier) type fiber laser device. The light emitted from each light source 10 has a wavelength of 1050 nm, for example.

An optical fiber 11 that propagates the light emitted from the light source 10 is connected to each light source 10. Each optical fiber 11 is, for example, a fumode fiber having a core diameter of about 20 μm. In this case, the light emitted from each light source 10 propagates through each optical fiber 11 in LP modes of about 2 to 4.

The optical combiner 20 is a member that connects the core of each optical fiber 11 and the core of the optical fiber 21. The optical combiner 20 is, for example, configured such that each optical fiber 11 and an optical fiber 21 having a diameter larger than the optical fiber 11 are end-face connected. The optical fiber 21 is, for example, a multimode fiber having a core diameter of about 50 μm to 100 μm.

FIG. 2 is a sectional view schematically showing a part of the optical device 30 shown in FIG. 1, and is a sectional view taken along the central axis of the optical fiber 31. FIG. 3 is a diagram schematically showing a cross section of the optical device 30 shown in FIG. 2 taken along the line III-III, and is a cross sectional view perpendicular to the central axis of the optical fiber 31. FIG. 4 is an enlarged view showing a part of the optical device 30 shown in FIG. As shown in FIGS. 2 to 4, the optical device 30 mainly includes an optical fiber 31, a quartz block 35, a housing 40, and a detector 50.

The optical fiber 31 is a multi-core fiber having a plurality of cores. The optical fiber 31 is connected to the core of the optical fiber 21 and propagates the signal light from the light source 10. The light emitting core 31a has a plurality of light detecting cores 32 arranged around the light emitting core 31a. Have. Further, the optical fiber 31 has a clad 31b surrounding the light emitting core 31a and the respective light detecting cores 32, and a coating layer 31c covering the clad 31b. At one end of the optical fiber 31, the coating layer 31c is peeled off and the clad 31b is exposed. The end face 31f of the optical fiber 31 on the side where the coating layer 31c is peeled off is fused to the quartz block 35 by an oxyhydrogen burner or the like.

As described above, the light emitting core 31a and the respective light detecting cores 32 are surrounded by the clad 31b which is a glass body having a lower refractive index than the light emitting core 31a and the respective light detecting cores 32. Therefore, the light emitting core 31a and each of the light detecting cores 32 are integrated by being surrounded by the glass body even at the portion connected to the quartz block 35.

In this embodiment, a total of four photodetecting cores 32 are provided, and they are arranged at equal intervals on a circle centered on the central axis of the light emitting core 31a. Further, in the present embodiment, the diameter of the light detection core 32 is made larger than the diameter of the light emission core 31a. Further, the light detection core 32 has a reflection portion 33 inside. The reflector 33 reflects the light propagating through the photodetection core 32 toward the outside of the optical fiber 31. Examples of such a reflection part 33 include a slant fiber Bragg grating. For example, by forming the slant FBG inclined at 45 degrees with respect to the central axis of the photodetection core 32 as the reflecting portion 33 in the photodetection core 32, the light propagating through the photodetection core 32 is converted into light. It can be reflected in a direction of 90 degrees with respect to the central axis of 32.

The quartz block 35 is a columnar body made of quartz having an entrance surface 35b and an exit surface 35a facing the entrance surface 35b and having an outer diameter larger than that of the optical fiber 31. One bottom surface of the columnar body serves as the entrance surface 35b, and the other bottom surface serves as the exit surface 35a. Such a quartz block 35 is, for example, a cylindrical body made of quartz and having a diameter of about 8 mm and a length of about 23 mm. The incident surface 35b is larger than the end surface 31f of the optical fiber 31, and the light emitting core 31a is fused to the central portion of the incident surface 35b. Further, the light detection core 32 is connected to the periphery of a connection portion of the incident surface 35b with the light emission core 31a.

The housing 40 is a member that houses a part of the quartz block 35 and the optical fiber 31. The housing 40 is formed in a tubular shape, and one end of the optical fiber 31 is inserted therein. Further, one end of the housing 40 is sealed by the quartz block 35. In the housing 40, the position of the quartz block 35 is fixed by fixing the outer peripheral surface 35c to the inner peripheral surface of the housing 40 with an adhesive such as silicone resin. The other end of the case 40 is sealed by a spacer 45. The spacer 45 has a through hole at the center, and the optical fiber 31 is inserted into the through hole. The space 42 formed by the inner peripheral surface of the housing 40, the quartz block 35, and the spacer 45 may be filled with a coolant that cools the optical fiber 31, the quartz block 35, and the housing 40.

The housing 40 is preferably made of, for example, a metal such as copper having excellent thermal conductivity. Further, the outer peripheral surface of the housing 40 may be water-cooled or air-cooled depending on the power of the laser light emitted from the laser device 1 and the like.

The detector 50 can detect the intensity of light emitted from the light detection core 32. In the present embodiment, the detector 50 is provided on the inner peripheral surface of the housing 40. Further, in this embodiment, the detectors 50 are provided in the same number as the photodetecting cores 32, and are provided at positions where the intensities of the light emitted from the photodetecting cores 32 can be individually detected. That is, each of the detectors 50 is provided at a position where the detector 50 is reflected by the reflecting portion 33 provided in each of the photodetecting cores 32 and emitted from the photodetecting core 32, but is incident. As such a detector 50, for example, a photodiode can be used.

Further, the detector 50 is connected to a control unit (not shown), the light detected by the detector 50 is converted into an electric signal, and the electric signal is sent to the control unit. In this way, the control unit can immediately observe the intensity of light detected by the detector 50.

Next, the operation and action of the laser device 1 of this embodiment will be described.

When signal light of a predetermined wavelength is emitted from each light source 10, each signal light propagates through the optical fiber 11, is combined by the optical combiner 20, and is emitted from the optical device 30 via the optical fiber 21. In the optical device 30, since the light emitting core 31a is connected to the incident surface 35b of the quartz block 35, the signal light propagating through the light emitting core 31a is incident on the quartz block 35. In this way, the signal light entering the quartz block 35 from the light emitting core 31a propagates in the quartz block 35 while expanding according to the numerical aperture, the energy density is reduced, and the signal light is emitted from the emitting surface 35a. The light emitted from the emission surface 35a is condensed by a processing head (not shown) and applied to the object to be processed. In this way, the light radiated to the object to be processed becomes heat by being absorbed by the object to be processed, and contributes to the processing.

However, part of the light emitted from the quartz block 35 may be reflected on the surface of the object to be processed, and part of the reflected light may return to the quartz block 35. In the laser device 1, when the light emitted from the emission surface 35a of the quartz block 35 and ideally collected at the processing point is vertically incident on the surface of the object to be processed and reflected vertically, the reflected light is The light is focused by a processing head (not shown), and a focus is formed on the light emitting core 31a on the incident surface 35b side of the quartz block 35. In this way, when the return light is recombined with the light emitting core 31a, it is easy to detect the intensity of the return light, so that measures such as safely stopping the emission of light are taken, which causes a problem. It is easy to prevent from happening.

However, in reality, ideal focusing is difficult due to the aberration of the lens of the processing head and the thermal lens effect. Further, since the surface of the object to be processed is generally formed with minute irregularities and slopes, the return light is incident on the periphery of the incident surface 35b of the quartz block 35 to which the light emitting core 31a is connected. There is a case. When the return light is incident on the position displaced from the light emitting core 31a in this way, the optical fiber 31 and the quartz block 35 may be heated.

FIG. 5 is a graph showing the relationship between the angle of the surface of the object to be processed with respect to the laser light and the ratio of the power of the return light to the power of the laser light when the laser light is applied to the object by simulation. .. Here, a laser device having an optical fiber composed of a core and a clad surrounding the core and a columnar quartz block connected to the emitting end of the optical fiber is used. The diameter of the quartz block is larger than the outer diameter of the optical fiber, and the optical fiber is connected to the center of the incident surface of the quartz block. The horizontal axis of the graph shown in FIG. 5 is the angle [deg] of the surface (working surface) of the object to be processed with respect to the output light emitted from the laser device. When the processing surface angle [deg] is zero, it means that the output light is incident perpendicularly to the processing surface. The vertical axis represents the ratio of the power [W] of the return light to the power [W] of the output light emitted from the laser device. In FIG. 5, the circles indicate the proportion of return light that enters the optical fiber including the core and the clad, and the triangles indicate the incidence on the incident surface of the quartz block other than the part to which the optical fiber is connected. The ratio of the returning light is shown.

As shown in FIG. 5, when the output light is vertically incident on the processed surface, the return light is likely to be incident on the optical fiber. However, it can be seen that as the angle of the processed surface with respect to the output light increases, the return light is more likely to be incident on the periphery of the part of the entrance surface of the quartz block where the optical fiber is connected. Further, as the angle of the processed surface with respect to the output light further increases, the amount of return light incident on the optical fiber also decreases on the incident surface of the quartz block at a position other than the portion to which the optical fiber is connected. It is considered that this is because it is difficult for the returning light to enter the quartz block. Therefore, it is considered that when the angle of the processed surface with respect to the output light becomes large to some extent, it becomes difficult for the return light to enter the quartz block, and the return light makes it difficult to heat the optical fiber or the quartz block.

Here, in the optical device 30, as described below, it is possible to suppress the heating of the optical fiber and the quartz block by the returning light.

In the optical device 30, the photodetection core 32 is connected to the periphery of the connection part with the light emission core 31a on the incident surface 35b of the quartz block 35. Therefore, it is possible to cause the return light that is incident on the incident surface 35b of the quartz block 35 around the connection portion with the light emitting core 31a to be incident on the light detecting core 32. Further, the optical device 30 includes the detector 50 that can detect the intensity of the light emitted from the light detection core 32. Therefore, the intensity of the return light that enters the light detection core 32 can be indirectly detected by the detector 50 as described above. In the optical device 30 of the present embodiment, the light propagating through the photodetection core 32 is reflected to the outside of the optical fiber 31 by the reflector 33, and the detector 50 detects the intensity of the light leaked from the optical fiber 31. As described above, since the light detection core 32 is provided with the reflecting portion 33, the return light can be emitted from the light detection core 32 and the intensity of the return light can be detected by the detector 50 with a simple configuration. ..

In the optical device 30, since the intensity of the return light incident on the photodetection core 32 can be detected by the detector 50 as described above, a countermeasure can be taken before the quartz block 35 and the optical fiber 31 are excessively heated by the return light. Can be given. As a result, it is possible to prevent the quartz block 35 and the optical fiber 31 from being heated by the returning light.

As a countermeasure, for example, when the intensity of light detected by one of the detectors 50 exceeds a preset threshold value, an alarm is issued by the control unit connected to the detector 50, and the laser device 1 is activated. It is possible to encourage the user to tilt the work surface. The optical fiber 31 and the quartz block 35 are heated by inclining the processed surface until the returning light becomes difficult to enter the quartz block 35, that is, until the intensity of the light detected by the detector 50 becomes smaller than the threshold value. Can be suppressed. Further, as another example of the above countermeasure, the angle of the processed surface is automatically adjusted until the intensity of the return light detected by the detector 50 becomes lower than the threshold value, or the return light detected by the detector 50 is used. It is conceivable to safely stop the emission of light from the optical device 30 when the intensity of the light exceeds the threshold value.

The plurality of light detection cores 32 are arranged at equal intervals on a circle centered on the central axis of the light emission core 31a as described above. Since the plurality of light detection cores 32 are provided in this way, it is easy to cause the return light to be incident on the light detection core 32 regardless of which direction the return light is incident on the light emission core 31a. Therefore, it becomes easy to detect the return light.

Further, each detector 50 is provided so as to individually detect the intensity of the light emitted from each photodetection core 32 as described above. Therefore, by discriminating which detector 50 detects the light, it is possible to specify which photodetecting core 32 the return light is incident on. Therefore, for example, it is possible to determine which direction the processed surface should be tilted to prevent the returning light from entering the quartz block 35. Therefore, it is easy to take appropriate measures before the quartz block 35 and the optical fiber 31 are excessively heated by the returning light, and it is easier to prevent the quartz block 35 and the optical fiber 31 from being heated by the returning light.

Further, the light emitting core 31a and the light detecting core 32 are integrated by the clad 31b having a lower refractive index than that of the light emitting core 31a and the light detecting core 32 at the portion connected to the quartz block 35 as described above. Has been done. As a result, in addition to the return light directly incident on the light detection core 32, a part of the return light incident on the clad 31b between the light emission core 31a and the light detection core 32 is also used for light detection via the clad 31b. It can be made incident on the core 32. Therefore, it becomes easy to detect the return light that is incident on the incident surface 35b of the quartz block 35 around the connection portion with the light emitting core 31a. Further, by integrating the light emitting core 31a and the light detecting core 32 as described above, the light emitting core 31a and the light detecting core 32 are kept in a relative positional relationship while the light emitting core 31a and the light detecting core 32 are maintained. It becomes easy to connect the core 31a and the light detection core 32 to a predetermined position of the quartz block 35.

Further, as described above, by making the diameter of the light detection core 32 larger than the diameter of the light emission core 31a, it becomes easy to detect the return light incident on the light detection core 32. The diameter of the light emitting core 31a is limited to some extent by the wavelength of the signal light propagating through the light emitting core 31a. On the other hand, the larger the diameter of the light detection core 32, the easier it is for the return light to enter the light detection core 32. By making it easier for the return light to be incident on the light detection core 32, it becomes easier to detect the return light that is incident at a position displaced from the light emission core 31a, and the quartz light block 31 and the optical fiber 31 are heated by the return light. It becomes easier to suppress this.

Further, by making the refractive index of the photodetection core 32 higher than that of the quartz block 35, reflection of the return light at the interface between the photodetection core 32 and the quartz block 35 is suppressed, and the return light is reflected. It becomes easy to make it enter the detection core 32. Therefore, it becomes easier to detect the return light that is incident on the position shifted from the light emitting core 31a, and it becomes easier to further suppress the heating of the quartz block 35 and the optical fiber 31 by the return light.

As described above, the optical device 30 can prevent the optical fiber 31 and the quartz block 35 from being heated by the returning light.

(Second embodiment)
Next, a second embodiment of the present invention will be described in detail with reference to FIG. In addition, the same or equivalent components as those of the first embodiment are designated by the same reference numerals, and the duplicate description will be omitted unless otherwise specified.

FIG. 6 is a cross-sectional view schematically showing a part of the optical device 130 included in the laser device according to the second embodiment of the present invention, and is a cross-sectional view taken along the central axis of the optical fiber 63. FIG. 7 is a diagram schematically showing a cross section taken along line VII-VII of the optical device shown in FIG. 6, and is a cross sectional view perpendicular to the central axis of the optical fiber 63.

The optical device 130 is the same as the optical device 30 according to the first embodiment except that a bundle fiber 131 is provided instead of the optical fiber 31. The bundle fiber 131 includes an optical fiber 63, a plurality of optical fibers 64, and a capillary 60 that is a glass body that bundles these optical fibers 63, 64 and integrates them. Each of the optical fibers 63 and 64 is integrated with the capillary 60 by being inserted into a through hole of the capillary 60 and fused.

In the bundle fiber 131, the optical fibers 63 and 64 are integrated by the glass body at one end as described above. Further, in the bundle fiber 131, the end portion on the side where the optical fibers 63 and 64 are thus integrated is fused to the quartz block 35. In this way, the optical fibers 63 and 64 are integrally fused and fused to the quartz block 35, so that one end of the optical fibers 63 and 64 is maintained while maintaining the relative positional relationship between the optical fibers 63 and 64. It becomes easy to connect the parts to predetermined positions of the quartz block 35.

The optical fiber 63 has a light emitting core 31a and a clad 61 surrounding the light emitting core 31a. Further, one end of the optical fiber 63 is inserted into the housing 40 through a through hole formed in the spacer 45, and one end thereof is fused to the quartz block 35 as described above. Therefore, one end of the light emitting core 31a is fused to the quartz block 35.

In this embodiment, a total of four optical fibers 64 are provided, and each optical fiber 64 has a photodetection core 132 and a cladding 62 surrounding the photodetection core 132. At the end on the quartz block 35 side, the optical fibers 64 are arranged at equal intervals on a circle centered on the central axis of the light emitting core 31a. Therefore, a total of four photodetection cores 132 are provided, and at the end on the quartz block 35 side, the photodetection cores 132 are arranged at equal intervals on a circle centered on the central axis of the light emission core 31a. Has been done.

The optical fibers 63 and 64 are separated from each other on the side opposite to the side connected to the quartz block 35, and the end of the optical fiber 64 on the side opposite to the side connected to the quartz block 35 is detected. Connected to the container 50. That is, one end of the light detection core 132 is connected to the quartz block 35, and the other end thereof is connected to the detector 50. Thereby, the light emitted from the photodetection core 132 can be made incident on the detector 50. Since the light emitting core 31a and the light detecting core 132 are separated from each other as described above, the light detecting core 132 can be bent, and the return light propagating through the light detecting core 132 can be transmitted to a desired place. Can be detected by the detector 50. Therefore, the degree of freedom in designing the optical device 130 can be improved.

In the optical device 130 of the present embodiment, the plurality of photodetecting cores 132 may be connected to one detector 50, but the plurality of photodetecting cores 132 should be connected to different detectors 50. Is preferred. By connecting the plurality of photo-detecting cores 132 to different detectors 50, it becomes easier to understand in which photo-detecting core 132 the return light is detected, and the bundle fiber 131 and the quartz block 35 are heated. It becomes easy to take appropriate measures to prevent this.

Further, the refractive index of the capillary 60 is preferably lower than the refractive index of the clad 61. That is, in the glass body including the capillaries 60 and the clad 61, the clad 61 surrounding the light emitting core 31 a serves as a high refractive index portion, and the capillary 60 surrounding the clad 61 includes a low refractive index portion having a lower refractive index than the clad 61. It is preferable that Since the high-refractive-index portion and the low-refractive-index portion are provided in this way, even if light leaks from the light-emitting core 31a, the light is a low-refractive-index portion from the cladding 61, which is a high-refractive-index portion. It is difficult to enter the capillary 60. Therefore, light propagating through the light emitting core 31a can be prevented from leaking and entering the light detecting core 32, and erroneous detection of return light can be suppressed. From the same viewpoint, the refractive index of the clad 62 is preferably lower than that of the capillary 60.

Although the present invention has been described above by taking the first and second embodiments as examples, the present invention is not limited to these. For example, the numbers of the light detection cores 32 and 132 and the detectors 50 are not particularly limited. For example, only one photodetection core 32, 132 may be provided. However, at the end portion on the quartz block 35 side, four or more photodetection cores 32 and 132 are provided at equal intervals on a circle centered on the central axis of the light emission core 31a, and each photodetection core is provided. A detector 50 is preferably provided so that the light propagating through 32 and 132 can be individually detected.

Moreover, in the said 1st and 2nd embodiment, the example in which the photodetection cores 32 and 132 were fusion-bonded to the quartz block 35 was demonstrated. However, the light detection cores 32 and 132 may be optically connected to the quartz block 35 so that the return light from the incident surface 35b of the quartz block 35 can enter.

Further, in the above-described first embodiment, the example in which the slant FBG inclined by 45 degrees with respect to the central axis of the light detection core 32 is used as the reflecting portion 33 has been described. However, the reflecting section 33 is not limited to this, and is not particularly limited as long as it can reflect the light propagating through the photodetection core 32 to the outside of the optical fiber 31. Further, the portion where the reflecting portion 33 is formed is not limited to the inside of the photodetecting core 32, and may be the end portion of the photodetecting core 32. Further, holes or defects may be formed in the photodetection core 32 instead of the reflecting portion 33. By forming a hole or a defect in the light detection core 32, the light propagating through the light detection core 32 is scattered by the hole or the defect, and the light can be detected by the detector 50.

Moreover, in the said 1st Embodiment, the example which uses the optical fiber 31 by which the core 31a for light emission and the core 32 for light detection were enclosed by the clad 31b was described. However, the multi-core fiber having the light emitting core 31a and the light detecting core 32 may be a so-called double clad fiber. FIG. 8 is a diagram schematically showing a cross section of a part of an optical device according to another embodiment. In addition, the same or equivalent components as those of the first embodiment are designated by the same reference numerals, and the duplicate description will be omitted unless otherwise specified. The optical device 230 shown in FIG. 8 includes an optical fiber 231. In the optical fiber 231, the clad 31b surrounding the light emitting core 31a includes an inner clad 31bi surrounding the light emitting core 31a and an outer clad 31bo surrounding the inner clad 31bi. The light detection core 32 is surrounded by the outer cladding 31bo. In this case, in the glass body including the inner clad 31bi and the outer clad 31bo, it is preferable that the inner clad 31bi be a high refractive index part and the outer clad 31bo be a low refractive index part having a lower refractive index than the inner clad 31bi.

Further, the method of integrating the light emitting core and the light detecting core at the end portion on the side connected to the quartz block is not limited to the forms exemplified so far. For example, the outer peripheral surface of the clad surrounding the light emitting core and the outer peripheral surface of the clad surrounding the light detecting core may be fused.

As described above, according to the present invention, an optical device capable of suppressing heating of an optical fiber or a quartz block by returning light is provided, and is expected to be used in the fields of processing machines, medical laser devices, and the like. To be done.

1... Laser device 10... Light source 20... Optical combiner 30, 130, 230... Optical device 31, 231... Optical fiber (multi-core fiber)
131... Bundled fiber 31a... Light emitting core 31b... Clad 31bi... Inner clad (high refractive index portion)
31bo... Outer clad (low refractive index part)
31c... Coating layers 32, 132... Photodetection core 33... Reflector 35... Quartz block 35a... Emission surface 35b... Incident surface 40... Housing 50... Detector 60... Capillaries 61, 62... Clad 63, 64... Optical fiber

Claims (10)

A quartz block having an entrance surface and an exit surface facing the entrance surface;
A light emitting core that is connected to the incident surface and propagates light that enters the quartz block,
A plurality of photodetection cores connected to the periphery of the connection portion with the light emitting core of the incident surface,
A plurality of detectors for detecting the intensity of the light emitted from the light detecting core,
Equipped with
An optical device, wherein the plurality of detectors individually detect the intensity of light emitted from the plurality of photodetection cores . At least in a portion connected to the quartz block, the light emitting core and the light detecting core are integrally surrounded by a glass body having a lower refractive index than the light emitting core and the light detecting core. The optical device according to claim 1, wherein the optical device comprises: The glass body has a high refractive index portion surrounding the light emitting core and a low refractive index portion having a lower refractive index than the high refractive index portion and surrounding the high refractive index portion,
The optical device according to claim 2, wherein the light detection core is surrounded by the low refractive index portion. A reflection portion is provided inside or at the end of the photodetection core,
The optical device according to any one of claims 1 to 3, wherein the detector detects the intensity of the light reflected by the reflector. Further comprising a metal housing for housing the light emitting core, the plurality of light detecting cores, and the plurality of detectors,
Each of the detectors is provided on the inner peripheral surface of the housing,
A reflective portion is provided inside each of the photodetection cores,
The detector is arranged to face the side of the reflecting portion apart from the reflecting portion in the radial direction of the light detection core,
The intensity of the light reflected by each of the reflectors is detected by the detector facing the respective reflector.
The optical device according to any one of claims 1 to 3, wherein: The light emitting cores and the light detecting core, light as claimed in any one of claims 1 5, characterized in that are separated from each other at the side opposite to the side connected to the quartz block device. The plurality of photodetection cores are arranged at equal intervals on a circle centered on the central axis of the light emission core, at least in a portion connected to the quartz block. 6. The optical device according to any one of 6 above. The optical device according to claim 1, wherein a diameter of the light detection core is larger than a diameter of the light emission core. 9. The optical device according to claim 1, wherein a refractive index of the light detection core is higher than a refractive index of the quartz block. An optical device according to any one of claims 1 to 9,
At least one light source for emitting light propagating through the light emitting core,
A laser device comprising:

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