Optical fiber amplifier and optical fiber laser having the same

Abstract

The present application provides a fiber amplifier and a fiber laser having the same, and the fiber amplifier includes: a seed source, a signal fiber, a pump source, a pump fiber and a coupler. The seed source and the pump source input the signal light and the pump light into the coupler through the signal fiber and the pump fiber respectively, and couple the pump light into the signal fiber through the coupler, so that the pump light is converted into the signal light, and the optical signal is amplified, and finally the coupled light after the optical signal is amplified is obtained. The coupler of the fiber amplifier of the present application only needs to set the fiber end cap and the focusing lens, and no color separation mirror is required to couple the pump light into the signal fiber, so that the pump light is converted into the signal light, and the optical signal is amplified. Compared with the prior art, the fiber amplifier and the fiber laser of the present application can meet the requirements of integration, miniaturization and low cost while amplifying the optical signal.

Description

Technical Field

[0001] The present application relates to the field of laser technology, and more particularly to an optical fiber amplifier and an optical fiber laser having the same, and more particularly to an optical fiber amplifier with an integrated and miniaturized structure and an optical fiber laser having the same. Background Art

[0002] Fiber lasers have the advantages of high electro-optical conversion efficiency, good heat dissipation and output beam quality, high stability, etc., and are widely used in laser welding, cutting, drilling, surface treatment and marking. With the advancement of science and technology, the requirements for processing technology in terminal application fields are also constantly increasing, and the most urgent demand is to increase the power level of fiber lasers.

[0003] Existing fiber lasers generally use fiber amplifiers to amplify the signal light power transmitted by optical fibers to meet the market's power requirements for high-power fiber lasers. Conventional high-power fiber lasers generally use pump light for multi-stage amplification. Each amplification stage requires multiple devices such as mode field adapters (MFA), cladding power strippers (CPS), isolators, beam expanders, and couplers. In order to improve the utilization rate of pump light, some solutions also require the addition of focusing lenses and dichroic mirrors in the coupler to make full use of the pump light. Therefore, there are many optical components and complex optical paths in high-power fiber lasers, and there are many problems such as large space occupation, many assembly and adjustment processes, low efficiency, and high cost. Many devices will also deteriorate the beam quality in various links such as assembly and fiber winding, affecting the processing performance of fiber lasers.

[0004] Based on this, it is necessary to invent an integrated and miniaturized optical fiber amplifier that can fully convert pump light into signal light for utilization, so as to meet the market's requirements for lightweight products. Summary of the invention

[0005] The purpose of this application is to provide a fiber amplifier and a fiber laser, which at least solve the problems of fiber lasers in the background technology that require many components, resulting in large space occupation, many assembly and adjustment processes, low efficiency, and poor laser quality. The fiber amplifier and fiber laser provided in this application can meet the market's requirements for lightweight products, fully couple the pump light to the signal fiber, and convert it into signal light for use.

[0006] To achieve the above objectives, this application provides the following technical solutions:

[0007] The present application provides an optical fiber amplifier, comprising a seed source, a signal optical fiber, a pump source, a pump optical fiber and a coupler. The seed source and the pump source input the signal light and the pump light into the coupler through the signal optical fiber and the pump optical fiber respectively, and couple the pump light into the signal optical fiber through the coupler, so that the pump light is converted into the signal light, and the optical signal is amplified, and finally the coupled light after the optical signal is amplified is obtained. The coupler comprises an optical fiber end cap and a focusing lens. The front end of the optical fiber end cap is connected to the signal optical fiber and the pump optical fiber. The focusing lens is located on the side of the optical fiber end cap away from the signal optical fiber and the pump optical fiber. The side of the optical fiber end cap close to the focusing lens is the first surface, the side of the focusing lens close to the optical fiber end cap is the second surface, and the side of the focusing lens away from the optical fiber end cap is the third surface. The first surface and the second surface are arranged in parallel, the third surface is a convex structure, and a color separation film is arranged on the third surface, the color separation film can allow the signal light to pass through, and the pump light is reflected to the connection point where the signal optical fiber and the optical fiber end cap are connected, and then enters the signal optical fiber, and is converted into the signal light by the action of the signal optical fiber. The signal light is mixed with the signal light generated by the seed source, and the process of converting the pump light into the signal light is repeated. The coupler can achieve the coupling effect of the signal light and the pump light, realize the amplification of the optical signal, and finally obtain the coupled light after the optical signal is amplified.

[0008] The present application also provides a fiber laser, which includes the above-mentioned fiber amplifier.

[0009] The difference between the fiber amplifier and fiber laser of the present application and the prior art is that the coupler of the prior art fiber amplifier usually needs to at least separately set up a fiber end cap, a focusing lens and a dichroic mirror in order to couple the pump light into the signal fiber, so that the pump light is converted into signal light, and the optical signal is amplified. The coupler of the fiber amplifier of the present application only needs to set up a fiber end cap and a focusing lens, and no longer needs to separately set up a dichroic mirror to couple the pump light into the signal fiber, so that the pump light is converted into signal light, and the optical signal is amplified. Compared with the prior art, the fiber amplifier and fiber laser of the present application can improve the energy conversion rate of the fiber laser while meeting the requirements of integration, miniaturization and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the embodiments of the present application or the technical solutions of the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0011] Figure 1 A schematic diagram of the structure of the optical fiber amplifier provided in this application;

[0012] Figure 2 A first structural schematic diagram of a coupler of an optical fiber amplifier provided in the present application;

[0013] Figure 3 A second structural schematic diagram of the coupler of the optical fiber amplifier provided in the present application;

[0014] Figure 4 It is a schematic diagram of the structure of a coupler of an existing optical fiber amplifier;

[0015] Figure 5 A third structural schematic diagram of the coupler of the optical fiber amplifier provided in the present application;

[0016] Figure 6 A fourth structural schematic diagram of the coupler of the optical fiber amplifier provided in the present application;

[0017] Figure 7 A fifth structural schematic diagram of the coupler of the optical fiber amplifier provided in the present application;

[0018] Figure 8 This is a sixth structural schematic diagram of the coupler of the optical fiber amplifier provided in the present application.

[0019] Figure numerals: 1. seed source, 2. pump source, 3. coupler, 11. signal fiber, 21. pump fiber, 31. fiber end cap, 32. focusing lens, 33. first sleeve, 34. second sleeve, 110. connection point, 310. offset point, 31a. first surface, 32a. second surface, 32b. third surface, L1. signal light, L2. pump light, L. coupling light. DETAILED DESCRIPTION

[0020] In order to enable those skilled in the art to better understand the present application, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are only part of the embodiments of the present application, and are not limitations on the scope of the rights of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0021] See also Figure 1 , Figure 1The schematic diagram of the structure of the optical fiber amplifier provided in the present application includes: a seed source 1, a signal optical fiber 11, a pump source 2, a pump optical fiber 21 and a coupler 3. The seed source 1 of the optical fiber amplifier of the present application inputs the signal light L1 into the coupler 3 through the signal optical fiber 11, the pump source 2 inputs the pump light L2 into the coupler 3 through the pump optical fiber 21, and the coupler 3 couples the pump light L2 into the signal optical fiber 11, so that the pump light L2 is converted into the signal light L1, and the amplification of the optical signal is realized, and finally the coupled light L after the optical signal amplification is obtained.

[0022] See also Figure 2 , Figure 2 The first structural schematic diagram of the coupler of the optical fiber amplifier provided in the present application. The coupler of the optical fiber amplifier of the present application includes an optical fiber end cap 31 and a focusing lens 32. The front end of the optical fiber end cap 31 is connected to the signal optical fiber 11 and the pump optical fiber 21, and the connection is usually performed by fusion splicing. The focusing lens 32 is located on the side of the optical fiber end cap 31 away from the signal optical fiber 11 and the pump optical fiber 21. The side of the optical fiber end cap 31 close to the focusing lens 32 is a first surface 31a, the side of the focusing lens 32 close to the optical fiber end cap 31 is a second surface 32a, and the side of the focusing lens 32 away from the optical fiber end cap 31 is a third surface 32b. The first surface 31a and the second surface 32a are arranged in parallel, the third surface 32b is a convex structure, and a dichroic film is arranged on the third surface 32b, the dichroic film can allow the signal light L1 to pass through, and the pump light L2 is reflected to the connection point 110 where the signal optical fiber 11 and the optical fiber end cap 31 are connected, and then enters the signal optical fiber 11, and the pump light L2 is converted into the signal light L1 by the action of the signal optical fiber 11. The signal optical fiber 11 can be a doped optical fiber doped with rare earth elements. Under the action of the rare earth elements in the signal optical fiber 11, the pump light L2 can be converted into the signal light L1.

[0023] The difference between the optical fiber amplifier of the present application and the prior art is that the coupler of the prior optical fiber amplifier usually needs to separately set at least an optical fiber end cap, a focusing lens and a dichroic mirror to achieve coupling of the pump light L2 to the signal light L1 and amplification of the optical signal. The coupler of the optical fiber amplifier of the present application only needs to set an optical fiber end cap 31 and a focusing lens 32 to achieve coupling of the pump light L2 to the signal light L1 and amplification of the optical signal.

[0024] The specific working principle of the coupler of the optical fiber amplifier of the present application for coupling the signal light L1 and the pump light L2 to generate the coupled light L is as follows: the signal light L1 output from the seed source 1 passes through the signal optical fiber 11, the optical fiber end cap 31 and the focusing lens 32, and is then output from the third surface 32b of the focusing lens 32. The pump light L2 output from the pump source 2 passes through the pump optical fiber 21, the optical fiber end cap 31 and the focusing lens 32, and is then reflected by the third surface 32b of the focusing lens 32 to the signal optical fiber 11. The signal optical fiber 11 converts the pump light L2 into the signal light L1, and the signal light L1 and the signal light L1 generated by the seed source are mixed and continue to be transmitted in the direction of the optical fiber end cap 31 and the focusing lens 32. The dichroic film of the focusing lens 32 allows the signal light L1 to pass through, and the pump light L2 is reflected to the signal optical fiber 11. In this way, the coupler 3 can realize the coupling effect of the signal light L1 and the pump light L2, realize the amplification of the optical signal, and finally obtain the coupled light L after the optical signal is amplified.

[0025] See also Figure 3 , Figure 3 This is a second structural schematic diagram of the coupler of the optical fiber amplifier provided in this application. Figure 2 Based on the coupler shown, Figure 3 The coupler shown also includes: a first sleeve 33, which is used to carry and fix the optical fiber end cap 31 and the focusing lens 32. The spatial positions of the optical fiber end cap 31 and the focusing lens 32 are kept unchanged, thereby ensuring that the pump light L2 and the signal light L1 are transmitted on the preset path.

[0026] See also Figure 4 , Figure 4 FIG. 1 is a schematic diagram of the structure of a coupler of an existing optical fiber amplifier. In this embodiment, Figure 4 The coupler shown and the present application Figure 2The coupler shown has the same structure, and also includes a fiber end cap 31 and a focusing lens 32. A dichroic film is provided on the third surface 32b of the focusing lens 32, and the dichroic film can allow the signal light L1 to pass through, but the pump light L2 is usually reflected to the offset point 310 on the fiber end cap 31, and the offset point 310 is located at a position on the side of the connection point 110 on the fiber end cap 31 away from the pump fiber 21. The above situation shows that after reducing the dichroic mirror, it is usually difficult for the pump light L2 to be reflected into the signal fiber 11. That is, in the absence of the dichroic mirror to adjust the optical path of the pump light L2, if the dichroic film on the focusing lens 32 is used to realize the pump light L2 being reflected into the signal fiber 11. It is necessary to make complex adjustments to the placement angles of the fiber end cap 31 and the focusing lens 32, or to set the convex surface of the color separation film to a specially customized aspheric structure. The above methods either affect the quality of the coupled laser beam, or fail to reduce the overall volume of the fiber laser, or have high production and processing costs. These are undoubtedly not ideal solutions.

[0027] To solve Figure 4 The problems encountered in the actual production of the coupler of the optical fiber amplifier shown in the figure. This application also provides another coupler. Please refer to Figure 5 , Figure 5 This is a third structural schematic diagram of the coupler of the optical fiber amplifier provided in the present application. Figure 5 The coupler shown and Figure 2 The coupler shown has the same general structure, and also includes a fiber end cap 31 and a focusing lens 32. The front end of the fiber end cap 31 is connected to the signal fiber 11 and the pump fiber 21. The focusing lens 32 is located on the side of the fiber end cap 31 away from the signal fiber 11 and the pump fiber 21. The side of the fiber end cap 31 close to the focusing lens 32 is a first surface 31a, the side of the focusing lens 32 close to the fiber end cap 31 is a second surface 32a, and the side of the focusing lens 32 away from the fiber end cap 31 is a third surface 32b. The first surface 31a and the second surface 32a are arranged in parallel, the third surface 32b is a convex structure, and a dichroic film is arranged on the third surface 32b, which allows the signal light L1 to pass through, and the pump light L2 can be reflected by the dichroic film.

[0028] Figure 5 The coupler shown and Figure 2The difference between the coupler shown is that when the first surface 31a of the fiber end cap 31 and the second surface 32a of the focusing lens 32 extend from the end point on the side close to the signal fiber 11 to the end point on the side close to the pump fiber 21, the first surface 31a and the second surface 32a are gradually inclined toward the side close to the third surface 32b. With such a design, when the pump light L2 is reflected, the span perpendicular to the output direction of the signal light L1 can be increased from the span of h to the span of H, thereby increasing the size of the reflection angle that can be tolerated when the pump light L2 is reflected by the dichroic film. That is, the dichroic film on the third surface 32b can more easily reflect the pump light L2 to the connection point 110 of the signal fiber 11, and then make the pump light L2 enter the signal fiber 11, and convert the pump light L2 into the signal light L1.

[0029] See also Figure 6 , Figure 6 This is a fourth structural schematic diagram of the coupler of the optical fiber amplifier provided in this application. Figure 5 Based on the coupler shown, Figure 6 The coupler shown also includes a first sleeve 33, which is also used to carry and fix the optical fiber end cap 31 and the focusing lens 32. The spatial positions of the optical fiber end cap 31 and the focusing lens 32 are kept unchanged, thereby ensuring that the pump light L2 and the signal light L1 are transmitted on the preset path.

[0030] See also Figure 7 , Figure 7 This is a fifth structural schematic diagram of the coupler of the optical fiber amplifier provided in the present application. Figure 7 The coupler shown is a preferred embodiment, the horizontal plane where the signal optical fiber 11 is located and the horizontal plane where the center point of the third surface 32b is located are not located in the same plane, and the horizontal plane where the center point of the third surface 32b is located is located at the horizontal plane where the signal optical fiber 11 is located, which is offset to the side close to the pump optical fiber 21. The signal optical fiber 11 is emitted from the center point of the third surface 32b, and at this time, the output signal light L1 is in a better collimated light form.

[0031] Since the horizontal plane where the signal optical fiber 11 is located and the horizontal plane where the center point of the third surface 32b is located are not located in the same plane, the upper and lower sides of the optical fiber end cap 31 and the focusing lens 32 are also not in the same horizontal plane. As in the above embodiment, directly setting the first sleeve 33 will cause a gap between the first sleeve 33 and the optical fiber end cap 31 and the focusing lens 32. In order to solve this problem, the present application provides another coupler. Please refer to Figure 8 , Figure 8 This is a sixth structural schematic diagram of the coupler of the optical fiber amplifier provided in this application. Figure 7 Based on the coupler shown, Figure 8The coupler shown also includes a first sleeve 33 and a second sleeve 34, wherein the first sleeve 33 is used to carry and fix the optical fiber end cap 31 and the focusing lens 32, and the second sleeve 34 is used to fill the gap between the first sleeve 33 and the optical fiber end cap 31 and the focusing lens 32. The spatial position of the optical fiber end cap 31 and the focusing lens 32 is kept stable and does not deviate, thereby ensuring that the pump light L2 and the signal light L1 are transmitted on the preset path.

[0032] In a preferred embodiment, the signal optical fiber 11 is a tapered optical fiber, which gradually becomes thicker from the side close to the seed source 1 to the side close to the optical fiber end cap 31, so that the pump light L2 is more easily coupled by the signal optical fiber 11 for optical signal conversion. In addition, the tapered optical fiber can also maintain the single-mode characteristics to obtain a high-quality light beam. At the same time, as the light spot gradually expands, the optical fiber mode field area increases, and the tapered doped optical fiber is used to suppress nonlinear effects such as SRS (stimulated Raman scattering), SBS (stimulated Brillouin scattering) and ASE (amplification of spontaneous emission), etc., to increase the maximum energy that each laser in the output laser can carry, and finally output a high-energy, high-power and single-mode laser.

[0033] In a preferred embodiment, the signal optical fiber 11 is a polarization-maintaining tapered optical fiber.

[0034] Furthermore, the core diameter range of the signal optical fiber 11 gradually increases from 5 to 30 μm to 50 to 100 μm, and the outer cladding diameter range of the signal optical fiber 11 gradually increases from 80 to 100 μm to 380 to 400 μm.

[0035] In the scheme of this embodiment, the pump light L2 is a laser of 910nm to 980nm, the signal optical fiber 11 is an ytterbium-doped optical fiber, that is, doped with Yb3+ element, and the signal light L1 is a laser of 1030nm to 1080nm. In other embodiments, the signal optical fiber 11 can also be an optical fiber doped with one or more rare earth elements such as Nd3+, Er3+, Ge3+, Pr3+, Ho3+, Eu3+, Dy3+, Tm3+, etc., which is selected according to the required wavelength requirements of the signal light L1, and equipped with corresponding seed source 1 and pump source 2. Here, the type of rare earth element doped with the signal optical fiber 11 is not limited.

[0036] The present application also provides a fiber laser, which includes the above-mentioned fiber amplifier.

[0037] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device that includes a series of elements are inherent to the elements. In the absence of more restrictions, the elements defined by the sentence "comprise one..." do not exclude the presence of other identical elements in the process, method, article or device that includes the elements. In addition, the above-mentioned technical solutions provided in the embodiments of the present application are consistent with the corresponding technical solutions in the prior art in the principle of implementation, and the part is not described in detail, so as not to be too much.

[0038] Specific examples are used herein to illustrate the principles and implementation methods of the present application, and the description of the above embodiments is only used to help understand the method and its core idea of ​​the present application. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present application, several improvements and modifications can be made to the present application, and the various embodiments in the present application can be combined, and these improvements, modifications and combinations also fall within the scope of protection of the claims of the present application.

Claims

1. A fiber amplifier, Features , comprising in sequence: a seed source (1), a signal optical fiber (11), a pump source (2), a pump optical fiber (21) and a coupler (3); The coupler comprises an optical fiber end cap (31) and a focusing lens (32); The front end of the optical fiber end cap (31) is connected to the signal optical fiber (11) and the pump optical fiber (21); The focusing lens (32) is located on a side of the optical fiber end cap (31) away from the signal optical fiber (11) and the pump optical fiber (21); The seed source (1) inputs the signal light (L1) into the coupler (3) through the signal optical fiber (11), and the pump source (2) inputs the pump light (L2) into the coupler (3) through the pump optical fiber (21); A side of the optical fiber end cap (31) close to the focusing lens (32) is a first surface (31a), a side of the focusing lens (32) close to the optical fiber end cap (31) is a second surface (32a), and a side of the focusing lens (32) away from the optical fiber end cap (31) is a third surface (32b); The first surface (31a) and the second surface (32a) are arranged in parallel, the third surface (32b) is a convex structure, and a dichroic film is arranged on the third surface (32b), the dichroic film can allow the signal light (L1) to pass through, the pump light (L2) is reflected by the dichroic film to the connection point (110) where the signal optical fiber (11) and the optical fiber end cap (31) are connected, and then enters the signal optical fiber (11), and the pump light (L2) is converted into signal light (L1) through the action of the signal optical fiber (11), and the optical signal is amplified, and finally the coupled light (L) after the optical signal is amplified is obtained; When the first surface (31a) of the optical fiber end cap (31) and the second surface (32a) of the focusing lens (32) extend from an end point on a side close to the signal optical fiber (11) to an end point on a side close to the pump optical fiber (21), the first surface (31a) and the second surface (32a) are gradually inclined toward a side close to the third surface (32b).

2. The optical fiber amplifier according to claim 1, Features The coupler also includes a first sleeve (33), which is used to carry and fix the optical fiber end cap (31) and the focusing lens (32).

3. The optical fiber amplifier according to claim 2, Features The horizontal plane where the signal optical fiber (11) is located and the horizontal plane where the center point of the third surface (32b) is located are not located in the same plane, the horizontal plane where the center point of the third surface (32b) is located is located at a side offset from the horizontal plane where the signal optical fiber (11) is located close to the pump optical fiber (21), and the signal optical fiber (11) is emitted from the center point of the third surface (32b).

4. The optical fiber amplifier according to claim 3, Features , the coupler also includes a second sleeve (34); The second sleeve (34) is used to fill the gap between the first sleeve (33) and the optical fiber end cap (31) and the focusing lens (32).

5. The optical fiber amplifier according to claim 1, Features The signal optical fiber (11) is a tapered optical fiber, which gradually becomes thicker from the side close to the seed source (1) to the side close to the optical fiber end cap (31).

6. The optical fiber amplifier according to claim 5, Features The core diameter range of the signal optical fiber (11) gradually increases from 5 to 30 μm to 50 to 100 μm, and the outer cladding diameter range of the signal optical fiber (11) gradually increases from 80 to 100 μm to 380 to 400 μm.

7. The optical fiber amplifier according to claim 1, Features The pump light (L2) is a laser with a wavelength of 910nm to 980nm, the signal optical fiber (11) is an ytterbium-doped optical fiber, and the signal light (L1) is a laser with a wavelength of 1030nm to 1080nm.

8. A fiber laser, Features , the fiber laser comprises the fiber amplifier according to any one of claims 1-7.

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