WO2005069453A1

WO2005069453A1 - Optical fiber and method for manufacturing same

Info

Publication number: WO2005069453A1
Application number: PCT/JP2004/018856
Authority: WO
Inventors: Tomomi Nakano; Yasuo Niino
Original assignee: Toyoda Koki Kabushiki Kaisha
Priority date: 2004-01-15
Filing date: 2004-12-10
Publication date: 2005-07-28
Also published as: JP3889746B2; JP2005203549A

Abstract

Disclosed is an optical fiber wherein a core member can be excited by more excitation lights and a laser beam can be obtained more efficiently. An optical fiber (1) comprising a core member (30) containing a laser active material and arranged in the longitudinal direction and a cladding member (10) covering at least a part of the core member (30) is characterized in that a plurality of the core members (30) are arranged in the optical fiber (1) along the longitudinal direction thereof so that the core members (30) are located in the peripheral portion of the cladding member (10) in a cross section of the optical fiber (1) perpendicular to the longitudinal direction. In this connection, a plurality of the core members (30) may be arranged in the optical fiber (1) or a single core member (30) may be arranged therein in such a manner that it turns around a plurality of times along the longitudinal direction of the optical fiber (1).

Description

Description Optical fiber and manufacturing method thereof

The present invention relates to an optical fiber used for fiber laser oscillation, comprising a core member containing a laser active material, and a clad member that transmits excitation light, and a method for manufacturing the same.

Conventionally, fiber laser oscillators that can obtain very high-quality laser light with high efficiency using pump light with relatively low beam quality, and optical amplifiers that can perform high-speed, large-capacity, long-distance transmission Various optical fibers used for such purposes have been proposed.

The optical fiber used for the fiber laser is usually about 2 to 12 [μιη] in diameter at the center of the cross section, which is made of a core material (single mode laser light is transmitted and doped with rare earth elements (Nd, Er)). Fiber shape). The laser light is confined in the core member by having a clad member having a lower refractive index than the core member (which is the first clad member and transmits the excitation light) around the core member. . Further, by providing a second clad member having a lower refractive index than the first clad member around the first clad member, the excitation light is confined in the first clad member.

When the excitation light incident on the optical fiber passes through the core member (collides with the core member), the rare-earth element in the core member is excited to generate laser light, and a single-mode laser is generated in the core member. Light remains. This laser Light has a small diameter (depending on the diameter of the core member) and a small divergence angle

(Because it depends on the wavelength of the generated laser beam, the refractive index of the core member and the first cladding member, etc.), the beam quality is very good (the beam quality of the laser beam depends on the radius of the emitted light and the spread angle of the emitted light). The smaller the product, the higher the beam quality.)

As shown in FIG. 8 (A), a conventional general optical fiber 1a (optical fiber used for fiber laser oscillation) has a longitudinal direction of a cylindrical first cladding member 10 (FIG. 8 (A)). A core member 30 containing a laser-active substance is disposed in the Z-axis direction (A)). FIG. 8 (B) shows a cross section perpendicular to the longitudinal direction of the optical fiber 1a (cross section BB in FIG. 8 (A)). As shown in FIG. 8 (B), in a conventional general optical fiber 1a, a core member 30 is disposed at a central portion of a first clad member 10 in a cross section perpendicular to the longitudinal direction.

When the excitation light L in enters from the end face perpendicular to the longitudinal direction of the optical fiber 1 a, the incident excitation light L in travels while being totally reflected in the first clad member 10. Then, when the excitation light L in that travels while being totally reflected in the first clad member 10 collides (accidentally) with the core member 30, the laser light is excited in the core member 30. ,

In the general optical fiber 1a, the diameter of the core member 30 is set to about 2 to 12 [μιη] in order to obtain higher quality laser light, and in order to obtain higher output laser light. The diameter of the first cladding member 10 is set to about 100 [μιη] in order to allow more excitation light to enter. Therefore, the sectional area of the core member 30 with respect to the sectional area of the first clad member 10 is very small. For this reason, as shown in FIG. 8 (), the excitation light Lin does not collide with the core member 30 and is totally reflected within the first cladding member 10 while the first cladding member 10 is not reflected. May orbit along the outer periphery of the. Fig. 8 (C) As shown in (1), an optical fiber having a rectangular cross-sectional shape of the first clad member 10 has been proposed to further reduce the circulating pump light L in. May occur.

In addition, since the excitation light L in has relatively poor beam quality, it is very difficult to aim and enter the core member 30 so as to collide with the core member 30.

Therefore, for example, in the field of fiber laser oscillators, a core member is wound around the outer peripheral surface of a cylindrical glass cylinder, and excitation light is incident from the vicinity of the outer peripheral end of the end surface of the cylindrical body using a prism, and the excitation light is emitted. There has been proposed a fiber laser oscillator that spirally circulates while being totally reflected inside a cylindrical body to further improve the laser output (see, for example, Japanese Patent Application Laid-Open No. H11-284425).

For example, in the field of optical amplifiers, as shown in FIGS. 8 (D) to (G), at least three core members 30 are provided in the first cladding member 10 of the optical fiber, and A multi-core fiber 1 b that has at least two regions 23 with changed mode field diameters to flatten the gain-wavelength characteristics not only when the gain is low but also when the gain is high (For example, refer to Japanese Patent Application Laid-Open No. H10-2442548). In the fiber laser oscillating device described in Japanese Patent Application Laid-Open No. H11-2844255, it is presumed that the core member is easily broken because the exposed core member is wound around the outer peripheral surface of the cylindrical body.

Further, in the fiber laser oscillation device described in Japanese Patent Application Laid-Open No. 11-284,255, excitation light is incident using a prism, and the excitation light is incident around the outer peripheral surface of the cylindrical body. Therefore, it is very difficult to make all the incident excitation light circulate when trying to make more excitation light incident (for example, if the diameter of the excitation light is increased, Excitation light whose incident angle does not satisfy the angle for total reflection inside the cylinder may increase. There is a potential).

In addition, the multi-core fiber lb described in Japanese Patent Application Laid-Open No. H10-224528 has a plurality of core members 30, but as shown in FIGS. 8 (E) to (G), Since the core member 30 is arranged substantially at the center of the cross section, it is estimated that the probability that the excitation light collides around the outer periphery of the first clad member 10 is low.

The present invention has been made in view of such a point, and in a fiber laser oscillation, more excitation light can excite a core member, and a light that can more efficiently obtain laser light. The task is to provide fiber. DISCLOSURE OF THE INVENTION ''

A first invention of the present invention is an optical fiber having a core member containing a laser active substance in a longitudinal direction and at least a part of the core member covered with a cladding member, wherein the plurality of core members are optical fibers. The plurality of core members are arranged in the longitudinal direction, and the plurality of core members are arranged at the edge of the clad member in a cross section perpendicular to the longitudinal direction of the optical fiber.

According to the first aspect, since the plurality of core members are arranged at the edge of the clad member, even if the excitation light totally reflected at the outer peripheral portion of the clad member is totally reflected so as to circulate, a higher value is obtained. Excitation light can collide with the core member with probability.

For this reason, more excitation light can excite the core member, and laser light can be obtained more efficiently.

A second invention of the present invention is the optical fiber according to the first invention, wherein the number of core members is one, and the core members are arranged so as to reciprocate a plurality of times in the longitudinal direction of the optical fiber. According to the second aspect, by arranging one core member so as to reciprocate in the longitudinal direction, a plurality of core members are arranged at the edge of the clad member.

Therefore, the excited laser light is generated inside one core member. Then, when extracting laser light from the output end of the single core member, since there is only one extraction port, a smaller diameter and higher quality laser light can be obtained.

A third invention of the present invention is a method for manufacturing an optical fiber, wherein a plurality of core members are arranged on an edge of the clad member in a cross section perpendicular to the longitudinal direction of the optical fiber, the method comprising: In this method, the core members are arranged in a longitudinal direction, and the clad members are heated until the clad members can flow, and the core members are pressed against the clad members.

According to the third invention, the optical fiber according to the first invention or the second invention can be manufactured more easily.

A fourth invention of the present invention is a method for manufacturing an optical fiber, wherein a plurality of core members are arranged on an edge of the clad member in a cross section perpendicular to the longitudinal direction of the optical fiber, the method comprising: And a ceramic precursor having a refractive index equal to that of the clad member or a ceramic precursor having a refractive index equal to or more than the refractive index of the clad member and less than the refractive index of the core member. And a method of covering an outer periphery of a clad member in which a core member is arranged on the outer periphery.

According to the fourth invention, the optical fiber according to the first invention or the second invention can be manufactured more easily.

According to a fifth aspect of the present invention, an optical fiber manufactured by the method for manufacturing an optical fiber according to the third or fourth aspect is introduced into a hollow member having a lower refractive index than the clad member, Clear the gap between the optical fiber and the hollow member. This is a method of filling with a ceramic precursor having a refractive index equivalent to that of the lad member or a ceramic precursor having a refractive index equal to or higher than the refractive index of the clad member and lower than the refractive index of the core member.

According to the fifth invention, the optical fiber according to the first invention or the second invention can be manufactured more easily.

A sixth invention of the present invention is an optical fiber having a core member containing a laser active substance in a longitudinal direction and at least a part of the core member being covered with a cladding member, wherein at least one of the optical fibers to which excitation light is incident is provided. The end surface is formed as an oblique surface (a flat surface or a curved surface) having a predetermined angle with respect to a cross section perpendicular to the longitudinal direction.

According to the sixth aspect, the end face on which the excitation light is incident is not perpendicular to the longitudinal direction, but is formed on an oblique surface (a flat surface or a curved surface) so as to have a predetermined angle. Can have a larger area.

Thereby, more excitation light can be incident from a larger incident surface, and more excitation light can excite the core member.

A seventh invention of the present invention is the optical fiber according to the sixth invention, further comprising at least one end face on which the excitation light is incident, having a predetermined angle with respect to a cross section perpendicular to the longitudinal direction. A plurality of oblique surfaces (flat or curved) are formed, and the end surface is formed in a polygonal pyramid shape.

According to the seventh aspect, by forming the end surface on which the excitation light is incident into a polygonal pyramid shape, the area of the excitation light incident surface is increased, and the excitation light is directed in the direction of each surface of the polygonal pyramid. An injection device can be arranged.

Thereby, more excitation light can be incident from a plurality of directions, and more excitation light can excite the core member.

An eighth invention of the present invention is the optical fiber according to the sixth invention or the seventh invention, wherein the optical fiber comprises: a pumping light incidence section for receiving the pumping light; And a pumping section that pumps the core member while the reflected pumping light is totally reflected.The cross section perpendicular to the longitudinal direction of a part of the pumping light incidence section is larger than the cross sectional area of the pumping section perpendicular to the longitudinal direction. Are configured so that the cross-sectional area becomes larger.

According to the eighth aspect, the portion where the area of the pumping light incident portion (the cross-sectional area perpendicular to the longitudinal direction) is the largest is the area of the pumping portion (the portion excluding the pumping light incident portion) of the optical fiber (the longitudinal direction). (The cross-sectional area perpendicular to the plane), and further increase the surface on which the excitation light is incident.

Thereby, more excitation light can excite the core member. Brief Description of Drawings

FIG. 1 is a schematic view of an embodiment of the optical fiber 1 of the present invention. FIG. 2 is a schematic view of an embodiment of a fiber laser oscillation device using the optical fiber 1 of the present invention. FIG. 3 is a diagram illustrating an example of a method of manufacturing the optical fiber 1. FIG. 4 is a view for explaining another example of the method for manufacturing the optical fiber 1. FIG. FIG. 5 is a diagram for explaining another example of the optical fiber 1. FIG. FIG. 6 is a diagram illustrating another example of the optical fiber 1. FIG. 7 is a diagram illustrating another example of a fiber laser oscillation device using the optical fiber 1 of the present invention. FIG. 8 is a diagram illustrating a conventional optical fiber. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings. FIG. 1 shows a schematic diagram of an optical fiber 1 of the present invention.

[Structure of optical fiber (Fig. 1)]

FIG. 1 (A) shows the optical fiber 1 of the present embodiment in the longitudinal direction (Fig. 2 shows an example of a cross-sectional view perpendicular to (z-axis direction in FIG. 1). The optical fiber 1 has a core member 30 in the longitudinal direction, and the core member 30 is doped with a laser active material (such as a rare earth element such as Nd or Er). Also, at least a part of the core member 30 is covered with a clad member 10 (hereinafter, the clad member 10 is referred to as a “first clad member 10 j”). In the example, the outer periphery of the first clad member 10 is further covered with the second clad member 20.

The relationship between the refractive indices of the respective members is as follows: the refractive index of the core member 30 (n 30)> the refractive index of the first clad member 10 (nlO)> the refractive index of the second clad member 20 (n 20)> It is set to be the refractive index of air. The second clad member 20 may be omitted.

Also, the concept that the core member 30 is “at least partially covered by the first clad member 10” is, as shown in FIG. 1 (B), a core section 30 that is perpendicular to the longitudinal direction. In addition to the case where the member 30 is disposed inside the first clad member 10, as shown in FIG. 1 (C), in a cross section perpendicular to the longitudinal direction, the core member 30 is the first clad member. Including the case where the core member 30 is located at the boundary between the first clad member 10 and the second clad member 20, as shown in FIG. This includes the case where they are arranged.

Then, the plurality of core members 30 are arranged in the longitudinal direction of the optical fiber 1, and the plurality of core members 30 are arranged on the edge of the first clad member 10 in a cross section perpendicular to the longitudinal direction. (See Fig. 1 (A)-(D)). Thus, even if the excitation light (for example, semiconductor laser light) incident from the end face of the optical fiber 1 travels while being totally reflected at the outer peripheral portion of the first cladding member 10, the excitation light is more reliably cored. By colliding with the member 30, the laser active substance of the core member 30 can be excited to generate output laser light. Note that the plurality of core members 30 arranged in the optical fiber 1 may be configured by arranging a plurality of core members 30 as shown in FIG. 1 (E), or FIG. As shown in (G) and (G), one or more core members may be arranged so as to reciprocate a plurality of times in the longitudinal direction of the optical fiber 1.

[Fiber laser oscillator using optical fiber (Fig. 2)]

Next, an example of a fiber laser oscillator using the optical fiber 1 described above will be described with reference to FIG. FIG. 2 (B) shows a cross section BB perpendicular to the longitudinal direction in FIG. 2 (A), and FIG. 2 (C) shows a cross section CC perpendicular to the longitudinal direction in FIG. 2 (A). I have.

In the example of FIG. 2 (A), the excitation light L in is input from the left end face of the optical fiber 1, and the output laser light L out is extracted from the right end face. In the example shown in FIG. 2A, the right end face of the optical fiber 1 (the end face on the side from which the output laser light is taken out) is narrowed down to a tapered portion Mtp by the tapered portion Mtp. 0 is bundled. By bundling, the diameter (corresponding to pb undle) in FIG. 2 (C), which is a diameter perpendicular to the longitudinal direction (corresponding to pb undle) by the plurality of core members 30 can be reduced, and the beam of the output laser light L out In the case of the optical fiber 1 shown in the example of Fig. 1 (F), it is not necessary to bundle the output laser light Lout since it is output from one place. In the case of the optical fiber 1 shown in the example of FIG. 1 (G), it is preferable to bundle them.

Note that the length of the excitation section M fiber for exciting the core member 30 with the excitation light L in is long enough for the entire excitation light L in to be used for excitation. Also, the cross section shown in FIG. 2 (C) shows a state in which the first clad member 10 and the second clad member 20 are left, but the cross section CC is such that the first clad member 10 is not left. Or the second clad member 20 may not be left. In the tapered portion Mt, neither the first clad member 10 nor the second clad member 20 is required.

At the end face of the optical fiber 1 on the incident side of the pump light L in, there is disposed a dike opening mirror 46 that transmits the pump light L in and reflects (does not transmit) the output laser light L out (in this example, (It is in contact with the input end face (left end face of optical fiber 1).) Instead of the dichroic mirror 46, a coating that transmits the excitation light L in and reflects the output laser light L out may be applied. The arrangement and coating of the dichroic mirror may be performed only on the end face of the core member 30 (in this case, the core member 30 on the left end face of the optical fiber 1).

The output laser light L out is converted into a parallel light on the end face of the optical fiber 1 on the side from which the output laser light L o XI t is extracted (the right end face of the optical fiber 1 in the example of FIG. 2 (A)). A collimating lens 42 for collecting the output laser light L out converted into a parallel light into a smaller diameter is disposed. The output laser light Lout condensed in this way has high output and accuracy with higher beam quality, and can be used for various applications such as laser processing and laser welding.

The optical fiber 1 used in the above-described fiber laser oscillator has an end face diameter (corresponding to cpc 1 ad in FIG. 2 (B)) of about 3 to 1 at which the excitation light Lin is incident. Since it can be as large as 0 [mm], the excitation light L in can be easily incident, and more excitation light L in can be incident.

Also, by bundling the core members 30 at the tapered portion Mtp, it is possible to bundle a plurality of conventional fiber laser optical fibers (fiber laser optical fibers shown in FIGS. 8 (B) and (C)). Since a small-diameter output laser beam L out can be obtained, the beam quality can be further improved.

[Optical fiber manufacturing method 1 (Fig. 3)] Next, an example of a method for manufacturing the optical fiber 1 described in FIG. 1 will be described with reference to FIGS. 3 (A) to 3 (E).

First, as shown in FIG. 3 (A), a first clad member 10 is formed. In the example of FIG. 3, the first clad member 10 is formed in a rectangular shape for convenience, but may be formed in a columnar shape, a polygonal column shape, or the like.

Next, as shown in FIG. 3 (B), a plurality of core members 30 are placed on the side surface of the first clad member 10 in parallel in the longitudinal direction. Further, heating is performed until the first clad member 10 becomes in a flowable state.

Then, as shown in FIG. 3 (C), the core member 30 is pressed in the direction of the first clad member 10 (the core member 30 is pushed into the first clad member 10 by a hot press HP or the like).

The steps shown in FIGS. 3 (B) to 3 (C) are performed over the outer periphery of the first clad member 10, whereby the structure shown in FIG. 3 (D) can be obtained. When the second clad member 20 is omitted, the optical fiber 1 in the state shown in FIG. 3 (D) may be used. If the second clad member 20 is not omitted, the outer periphery is further covered with a solution-like ceramic precursor (a coating agent such as polysilazane) in the state shown in FIG. The second clad member 20 is formed. At this time, a ceramic precursor having a refractive index smaller than that of the first clad member 10 is used.

Through the steps described above, it is possible to realize the optical fiber 1 in which the plurality of core members 30 are arranged on the edge of the first clad member 10.

[Optical fiber manufacturing method 2 (Fig. 4)]

Next, an example of a manufacturing method different from the manufacturing method of the optical fiber 1 described in FIG. 3 will be described with reference to FIGS. 4 (A) to 4 (D).

First, as shown in FIG. 4 (A), a first clad member 10 is formed. Although the first clad member 10 is formed in a cylindrical shape for convenience in the example of FIG. 4, it may be formed in a rectangular or polygonal column shape.

Next, as shown in FIG. 4 (B), a plurality of core members 30 are arranged on the side surface of the first clad member 10 in parallel in the longitudinal direction.

Then, as shown in FIG. 4 (C), the outer periphery is further covered with a solution-like ceramic precursor (a coating agent such as polysilazane) and fired. The ceramic precursor used at this time may be a ceramic precursor having a refractive index equivalent to that of the first clad member 10 or a refractive index not less than the refractive index of the first clad member 10 and less than the refractive index of the core member 30. Is used. As a result, the fired ceramic precursor is thermally bonded to the first clad member 10 prepared in FIG. 4 (A), and the fired ceramic precursor is bonded to the first clad member 10 prepared in FIG. 4 (A). Together with the body, a new first clad member 10a is formed, and the core member 30 is fixed.

When the second clad member 20 is omitted, the optical fiber 1 fired from the state shown in FIG. 4 (C) may be used. When the second clad member 20 is not omitted, in the optical fiber 1 fired from FIG. 4 (C), the outer periphery is further reduced to a solution-like ceramic precursor (which is smaller than the refractive index of the first clad member 10). (A ceramic precursor having a refractive index) and baking to form a second clad member 20.

Alternatively, a second clad member 20 (hollow member such as a hollow glass rod) having a refractive index lower than that of the first clad member 10 is formed, and a third clad member 20 is formed in the hollow portion of the second clad member 20. Insert the optical fiber in the state shown in Fig. (D) or Fig. 4 (B) or Fig. 4 (C). Then, a gap between the optical fiber and the second clad member 20 is formed by a solution-like ceramic precursor having the same refractive index as that of the first clad member 10 or the refractive index of the first clad member 10 or more and the core. Solution ceramic having a refractive index less than that of member 30 An optical fiber 1 is formed by filling with a precursor and firing.

[Other examples (Figs. 5 to 7)]

The optical fiber 1 shown in FIG. 1 shows an example of a structure in which the incident pump light L in collides with and excites the core member 30 with a higher probability, but the optical fiber shown in FIG. 5 to FIG. 1 shows an example of the structure of the optical fiber 1 to which more pump light L in can be incident. In this case, one core member 30 may be disposed at the center, as in a conventional optical fiber, or a plurality of core members may be disposed on the outer periphery of the first clad member 10 as shown in FIG. Thus, the output laser light L out can be obtained with higher efficiency.

5 and 6, the illustration of the core member 30 is omitted for the sake of explanation.

[Example of an optical fiber in which the incident surface of the excitation light is formed obliquely (Figs. 5 (A) and (B))]

As shown in FIGS. 5 (A) and (B), the end face S on which the excitation light Lin is incident (hereinafter, referred to as “excitation light incidence end face S”) is taken with respect to a cross section perpendicular to the longitudinal direction. It is formed on an oblique surface so as to have a predetermined angle (angle Θ in Fig. 5 (B)). In the present embodiment, the shape of the excitation light incident end surface S is a flat surface, but the shape of the excitation light incident end surface S may be formed as a curved surface to have a lens effect.

In this case, when the incident angle of the incident excitation light L in (the angle formed by the perpendicular to the excitation light incident end face S and the excitation light L in) becomes large, the excitation light does not enter the first clad member 10 but enters the first cladding member 10. It is preferable that the incident angle of the excitation light L in is as small as possible because the excitation light L in reflected by the surface of the end face S is likely to increase (in the example of FIG. 5 (B), the incident angle is 0 °). Shown). Further, in this case, since the angle θΐι between the excitation light L in traveling in the first clad member 10 and the side surface of the first clad member 10 tends to be large, the outer periphery of the first clad member 10 is The excitation light Lin may be covered with a member (such as a mirror) that totally reflects the excitation light Lin.

[Example of optical fiber with excitation light incident surface formed in a polygonal pyramid shape (Fig. 5 (C) and (D))]

As another embodiment, as shown in FIGS. 5 (C) and (D), the excitation light incident end face S is formed into a polygonal pyramid (a quadrangular pyramid in the examples of FIGS. 5 (C) and (D)). Form. Hereinafter, differences from FIGS. 5 (A) and 5 (B) will be described.

In this case, not only does the area of the excitation light incident end face S increase, but also the excitation light L in incident means (the excitation light L in generator, etc.) in the direction of the normal to each plane of the excitation light incident end face S. ) Can be arranged, so that more excitation light L in can be incident more easily.

[Example of an optical fiber with a larger diameter of the pumping light incident surface (Figs. 6 (A) to (C))]

As still another embodiment, as shown in FIGS. 6 (A) to 6 (C), an optical fiber 1 is used to enter an excitation light incident section M in which an excitation light L in is incident, and an incident excitation light L is incident. When in is divided into the excitation section M fiber that excites the core member 30 while total reflection occurs, a part of the excitation light incidence section M in is larger than the area S cross section perpendicular to the longitudinal direction of the excitation section M fiber. The excitation light incident part M in is configured so that the area S max of the cross section perpendicular to the longitudinal direction becomes larger.

The excitation light L in may be incident perpendicularly to the excitation light incident end face S (the incident angle is 0 °) (see FIG. 6 (B)), or the reflection angle in the excitation section M fiber (It is also possible to make the incident angle (（6a, 66c in FIG. 6 (C)) such that Θ7a, Θ7c) in FIG. 6 (C) is small. Hereinafter, since it is the same as FIG. 5 (A) to (D), the description is omitted.

[Fiber laser oscillator in other examples (Fig. 7)]

Next, a fiber laser oscillator using the optical fiber 1 shown in FIGS. 5 (A) and (B) will be described.

The example of the fiber laser oscillation device shown in FIG. 7 (A) is an example in which the number of core members 30 is plural, and the example of the fiber laser oscillation device shown in FIG. 7 (B) is the core member 30. This is an example in the case of one. The mounting method of the die mirror 46 is different from that of the fiber laser oscillator shown in Fig. 2 (A). Hereinafter, this difference will be described.

In the example shown in FIGS. 7 (A) and (B), one dichroic mirror 46 is provided on the end face of one core member 30 and the dichroic mirror 46 is provided on the excitation light incident end face S. Is not provided. In addition, a coating may be applied instead of the dichroic mirror. In this case, a member (a dichroic mirror 46 or the like) that reflects the output laser light L out is attached to each end face of the core member 30 (each end face on the excitation light incident end face S side) on the end face of the core member 30. What is necessary is just to provide so that it may contact | abut so that it may become perpendicular to the longitudinal direction of the said core member.

The end faces of the core member 30 on the excitation light incident end face S side may be connected as shown by a one-point line in FIG. 7 (A) (C in FIG. 7 (A)). part). Since the connected core member 30 has no end face, there is no need to provide a member that reflects the output laser light Lout.

The optical fiber 1 of the present invention and its manufacturing method are not limited to the shape, configuration, structure, method, and the like described in the present embodiment, and various changes, additions, and deletions may be made without departing from the spirit of the present invention. It is possible.

The numerical values used in the description of the present embodiment are examples, and the present invention is not limited to these numerical values. In the present embodiment, a semiconductor laser is used for the excitation light Lin, but various types of excitation light can be used. Industrial applicability

The optical fiber 1 of the present invention can be applied to various devices using laser light, such as a laser processing device.

Claims

The scope of the claims

1. An optical fiber having a core member containing a laser active substance in a longitudinal direction and at least a part of the core member covered with a cladding member, wherein a plurality of core members are arranged in the longitudinal direction of the optical fiber. An optical fiber, wherein the plurality of core members are arranged at an edge of the clad member in a cross section perpendicular to the longitudinal direction of the optical fiber.

2. The optical fiber according to claim 1, wherein

An optical fiber, wherein the number of core members is one, and the core member is arranged so as to reciprocate a plurality of times in the longitudinal direction of the optical fiber.

3. A method for manufacturing an optical fiber in which a plurality of core members are arranged on an edge of a clad member in a cross section perpendicular to the longitudinal direction of the optical fiber, the core being disposed on an outer periphery of the clad member and in a longitudinal direction. Arrange the members,

A method for manufacturing an optical fiber, comprising heating a clad member to a flowable state and pressing a core member against the clad member.

4. A method for manufacturing an optical fiber in which a plurality of core members are arranged at an edge of a clad member in a cross section perpendicular to the longitudinal direction of the optical fiber, the core being disposed on an outer periphery of the clad member and in a longitudinal direction. Arrange the members,

A ceramic precursor having a refractive index equivalent to that of the clad member or a ceramic precursor having a refractive index equal to or greater than the refractive index of the clad member and less than the refractive index of the core member; A method for producing an optical fiber, which covers an outer periphery.

5. The optical fiber manufactured by the optical fiber manufacturing method according to claim 3 or 4 is inserted into a hollow member having a lower refractive index than the cladding member, and a gap between the optical fiber and the hollow member is formed. A ceramic precursor having the same refractive index as the clad member, or a refractive index equal to or higher than the refractive index of the clad member A method for producing an optical fiber, comprising filling a ceramic precursor having a refractive index less than the refractive index of one core member.

6. An optical fiber having a core member containing a laser active substance in the longitudinal direction and at least a part of the core member covered with a cladding member, wherein at least one end face for receiving the excitation light has a longitudinal direction. An optical fiber formed on an oblique surface having a predetermined angle with respect to a bent surface perpendicular to the optical fiber.

7. The optical fiber according to claim 6, wherein

Further, at least one end face on which the excitation light is incident, a plurality of oblique faces having a predetermined angle with respect to a cross section perpendicular to the longitudinal direction are formed, and the end face is formed in a polygonal pyramid shape. An optical fiber.

8. The optical fiber according to claim 6 or 7, wherein

The optical fiber is composed of a pumping light input section for inputting pumping light, and an excitation section for pumping the core member while totally reflecting the incident pumping light.

The light is characterized in that a cross-sectional area of a cross section perpendicular to the longitudinal direction in a part of the excitation light irradiation part is larger than a cross-sectional area of a cross section perpendicular to the longitudinal direction in the excitation part. fiber.