Multistage optical fiber amplifier

Abstract

The invention relates to the technical field of laser, in particular to a multistage optical fiber amplifier which comprises a pump laser, a signal pump beam combiner and an optical fiber, the pump laser is used for outputting pump light, and the signal pump beam combiner is used for coupling input signal light and pump light into the optical fiber; the optical fiber is a double-clad optical fiber, the optical fiber comprises an optical fiber core, an inner cladding, an outer cladding and a protective layer, rare earth element SiO2 is doped in the optical fiber core, the optical fiber core serves as a main transmission channel of laser, the corresponding wavelength is designed to be a single mode, and output laser is a fundamental transverse mode; the diameter of the inner cladding is larger than that of the outer cladding, the inner cladding is used for transmitting pump light, the pump laser adopts a multi-mode pump source, and the pump light is output through the multi-mode pump source to achieve output of high power and pulse energy; the optical fiber amplifier solves the technical problem of low efficiency caused by too simple structure and principle of an existing optical fiber amplifier, and meanwhile, the use stability is improved by arranging the accommodating box body.

Description

Technical Field

[0001] The invention relates to the field of laser technology, and in particular to a multi-stage optical fiber amplifier. Background Art

[0002] A fiber amplifier is a device used to amplify optical signals in fiber-optic communications. It can compensate for the loss of optical signals during long-distance transmission, thereby improving communication quality. Compared with traditional optical-electrical-optical repeaters, fiber amplifiers can directly amplify optical signals without converting them into electrical signals, which makes them highly transparent to the format and rate of the signal, simplifying the entire fiber-optic communication transmission system.

[0003] There are three main types of fiber amplifiers: fiber amplifiers, Raman amplifiers, and semiconductor optical amplifiers. Among them, fiber amplifiers use rare earth ions (such as erbium, praseodymium, thulium, etc.) doped in optical fibers as laser active substances to achieve amplification. Different dopants have different gain bandwidths. For example, the gain bandwidth of erbium-doped fiber amplifiers (EDFA) is relatively wide, covering the S, C, and L bands; the gain bandwidth of thulium-doped fiber amplifiers is the S band; and the gain band of praseodymium-doped fiber amplifiers is around 1310nm.

[0004] Raman amplifiers use the Raman scattering effect to amplify signal light. It is a distributed amplification process with a very wide working bandwidth and almost no restrictions, but the cost is relatively high. Semiconductor optical amplifiers (SOAs) usually refer to traveling wave optical amplifiers. Their working principle is similar to that of semiconductor lasers. They have a wider working bandwidth, but the gain amplitude is slightly smaller and the manufacturing difficulty is relatively high.

[0005] Another important feature of fiber amplifiers is that they can support time-division multiplexing and wavelength-division multiplexing networks with multiple bit rates, modulation formats, and different wavelengths. In particular, the emergence of EDFA has made wavelength division multiplexing (WDM) technology play an important role in fiber-optic communications.

[0006] The invention patent of Chinese patent application No. 202410498337.3 discloses 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. In this application, the coupler of the fiber amplifier only needs to be provided with a fiber end cap and a focusing lens, and no separate dichroic 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 this application can meet the requirements of integration, miniaturization and low cost while amplifying the optical signal. The technical solution proposed by the above invention cannot effectively improve the amplification effect of the optical fiber signal, because only conventional optical signal amplification means are used. Summary of the invention

[0007] Therefore, in response to the above problems, the present invention proposes an optical fiber amplifier, which solves the technical problem of low efficiency caused by the overly simple structure and principle of the existing optical fiber amplifier by optimizing the optical fiber core expansion and combining two stages of pre-amplification and one stage of main amplification. At the same time, the stability of use is improved by setting a containing box.

[0008] To achieve the above object, the present invention adopts the following technical solution: a multi-stage fiber amplifier, comprising a pump laser, a signal pump combiner, and an optical fiber, wherein the pump laser is used to output pump light, and the signal pump combiner is used to couple input signal light and pump light into the optical fiber; The optical fiber is a double-clad optical fiber, comprising an optical fiber core, an inner cladding, an outer cladding and a protective layer. The optical fiber core is doped with the rare earth element SiO2, which serves as the main transmission channel of the laser. The corresponding wavelength is designed to be single-mode, and the output laser is the fundamental transverse mode; The diameter of the inner cladding is greater than the diameter of the outer cladding, the inner cladding is used to transmit pump light, and the pump laser adopts a multi-mode pump source, and outputs pump light through the multi-mode pump source to achieve output of high power and pulse energy; The outer cladding is composed of a polymer material, and its refractive index is less than that of the inner cladding; The protective layer is made of hard plastic and is used to protect the optical fiber; The pump light is transmitted through the inner cladding, and the pump light excites the rare earth element SiO2 doped in the optical fiber core, thereby achieving amplification of the optical signal.

[0009] Furthermore, the pump light is transmitted through the inner cladding.

[0010] Furthermore, the optical fiber core is doped with rare earth elements, and the optical signal can be amplified by doping with rare earth elements.

[0011] Furthermore, the pump laser, the signal pump combiner, and the optical fiber are all placed in a containing box, and the containing box is used to ensure the stability of the optical fiber entry and exit ports. The containing box includes an upper cover body and a lower cover body that cover each other, and the upper cover body is provided with a first groove, and the lower cover body is provided with a second groove. When the upper cover body and the lower cover body cover each other, the first groove and the second groove cooperate with each other to form an entrance and an exit for the optical fiber to enter and exit.

[0012] Furthermore, an auxiliary supporting device for enhancing the support stability of the optical fiber and the port of the accommodating box is provided in the accommodating box, and the auxiliary supporting device includes a first supporting connector, a second supporting connector, and an adjusting screw. The adjusting screw and the first supporting connector are mutually connected, and the adjusting screw and the second supporting connector are mutually connected. The horizontal movement of the first supporting connector and the second supporting connector is controlled by the rotation of the adjusting screw.

[0013] Furthermore, a first support block and a second support block are provided in the accommodating box, and the first support block and the second support block are respectively arranged at the inlet and the outlet to provide placement space for the first supporting connecting member and the second supporting connecting member, and the first support block and the second support block are fixedly connected to the accommodating box.

[0014] Furthermore, the first supporting connecting member and the second supporting connecting member have the same structure, the first supporting connecting member includes a first sleeve and a first rack fixedly connected, the second supporting connecting member includes a second sleeve and a second rack fixedly connected, the first sleeve is placed on the first supporting block and extends outward through the inlet, the second sleeve is placed on the second supporting block and extends outward through the outlet, and the outward extension distance of the first sleeve and the second sleeve is controlled by the adjusting screw.

[0015] Furthermore, the first rack is provided with a first meshing tooth, the second rack is provided with a second meshing tooth, and the adjusting screw is provided with a third meshing tooth, and the third meshing tooth is meshed with the first meshing tooth and the second meshing tooth at the same time, and the first sleeve and the second sleeve can be extended outward or retracted inward at the same time by rotating the adjusting screw.

[0016] Furthermore, the inner circumferential side surfaces of the first sleeve and the second sleeve are both covered with a buffer rubber pad.

[0017] Furthermore, the maximum outward extension length of the first sleeve and the second sleeve is 50 mm.

[0018] By adopting the above technical solution, the beneficial effects of the present invention are: 1. Compared with the existing optical fiber amplifier, the present invention mainly proposes a nonlinear control technology for expanded core optical fiber, optimizes the preparation process of expanded core optical fiber, and adopts an amplification scheme combining two-stage pre-amplification and one-stage main amplification to effectively solve the problems of low pump power threshold and low coupling efficiency, thereby improving the output power of the laser. At the same time, by improving the containing box for placing the optical fiber amplifier, on the one hand, complete protection is provided for the optical fiber amplifier, and on the other hand, auxiliary support is provided for the entry and exit of the optical fiber to ensure that the optical fiber will not interfere with the groove of the containing box and thus affect the transmission efficiency of the optical signal. Specifically, the containing box includes an upper cover and a lower cover that cover each other, so as to facilitate the installation, placement, and subsequent maintenance and adjustment of the optical fiber amplifier.

[0019] 2. In the present invention, bait is added to the optical fiber core and rare earth elements are doped to amplify the optical signal.

[0020] 3. Compared with conventional optical fiber storage devices, the storage box in the present invention improves the structure of the entrance and exit to ensure that the optical fiber will not cause structural interference with the storage box when entering and exiting the storage box, thereby causing possible bending.

[0021] 4. In the present invention, an auxiliary support device is provided, wherein the main working principle of the auxiliary support device is: by rotating the adjusting screw from the outside, and then by adjusting the meshing relationship between the screw and the first supporting connector and the second supporting connector, the extension and retraction of the first sleeve and the second sleeve are controlled. The advantage is that the external rotating adjusting screw will not affect the internal pump laser, signal pump combiner, and optical fiber. Since all three are high-precision components, the structural design avoids affecting the high-precision components in the accommodating cavity.

[0022] 5. The first sleeve and the second sleeve in the present invention are respectively arranged at the inlet and the outlet through the first support block and the second support block, and the first sleeve and the second sleeve are extended outward or retracted inward by controlling the adjusting screw. The extension amount outward and the retraction amount inward are adjusted according to actual use requirements, and the optical fiber cable is transported outward through the first sleeve and the second sleeve. In other words, the first sleeve and the second sleeve serve as protective tubes for the optical fiber cable. The two increase the contact area with the optical fiber cable by extending outward according to actual conditions, thereby providing better protection for it, avoiding hard contact between the optical fiber cable and the port of the accommodating box, which may cause bending and affect the optical fiber transmission efficiency.

[0023] 6. In the present invention, by arranging a buffer rubber pad in the first sleeve and the second sleeve, the buffer rubber pad can better protect the optical fiber cable from damage and bending. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings: Figure 1 It is the working principle diagram of the present invention; Figure 2 It is a schematic diagram of the signal transmission of the present invention; Figure 3 It is a schematic diagram of the three-dimensional structure of the containing box in the present invention; Figure 4 It is a schematic diagram of the front structure of the containing box in the present invention; Figure 5 It is a schematic diagram of the side structure of the containing box in the present invention; Figure 6 It is a schematic diagram of the internal structure of the containing box in the present invention; Figure 7 It is a schematic diagram of the structure of the auxiliary support device in the present invention. DETAILED DESCRIPTION

[0025] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0026] See also Figure 1-Figure 7 The present invention provides a multi-stage fiber amplifier, comprising a pump laser, a signal pump combiner, and an optical fiber 2, wherein the pump laser is used to output pump light, and the signal pump combiner is used to couple input signal light and pump light into the optical fiber 2; The optical fiber 2 is a double-clad optical fiber, which includes an optical fiber core, an inner cladding, an outer cladding and a protective layer. The optical fiber core is doped with the rare earth element SiO2, which serves as the main transmission channel of the laser. The corresponding wavelength is designed to be single-mode, and the output laser is the fundamental transverse mode; The diameter of the inner cladding is greater than the diameter of the outer cladding, the inner cladding is used to transmit pump light, and the pump laser adopts a multi-mode pump source, and outputs pump light through the multi-mode pump source to achieve output of high power and pulse energy; The outer cladding is composed of a polymer material, and its refractive index is less than that of the inner cladding; The protective layer is made of hard plastic and is used to protect the optical fiber 2; The pump light is transmitted through the inner cladding, and the pump light excites the rare earth element SiO2 doped in the optical fiber core, thereby achieving amplification of the optical signal.

[0027] The pump light is transmitted through the inner cladding; The optical fiber core is also doped with bait, and the optical signal can be amplified by doping with rare earth elements; The bait doped with rare earth elements is a known raw material.

[0028] The pump laser, the signal pump combiner, and the optical fiber are all placed in a housing 1. The housing 1 is used to ensure the stability of the optical fiber 2 in and out of the port. The housing 1 includes an upper cover 11 and a lower cover 12 that cover each other. The upper cover 11 is provided with a first groove 111, and the lower cover 12 is provided with a second groove 121. When the upper cover 111 and the lower cover 121 cover each other, the first groove 111 and the second groove 121 cooperate with each other to form an entrance and an exit for the optical fiber 2 to enter and exit. The housing 1 is provided with a support for enhancing the support stability of the optical fiber 2 and the port of the housing 1. The auxiliary support device comprises a first support connector 3, a second support connector 5, and an adjusting screw 4. The adjusting screw 4 is connected to the first support connector 3 in cooperation with each other, and the adjusting screw 4 is connected to the second support connector 5 in cooperation with each other. The horizontal movement of the first support connector 3 and the second support connector 5 is controlled by the rotation of the adjusting screw 4. The first support block 8 and the second support block 7 are arranged in the accommodating box 1. The first support block 8 and the second support block 7 are respectively arranged at the inlet and the outlet, and are used to provide the first support connector 3 and the second support connector 5 with a first support block 8 and a second support block 7. The first support block 8 and the second support block 7 are fixedly connected to the accommodating box 1, the first support connector 3 and the second support connector 5 have the same structure, the first support connector 3 includes a first sleeve 31 and a first rack 32 that are fixedly connected, the second support connector 5 includes a second sleeve 51 and a second rack 52 that are fixedly connected, the first sleeve 31 is placed on the first support block 8 and extends outward through the inlet, the second sleeve 51 is placed on the second support block 7 and extends outward through the outlet, and the first sleeve 31 and the second sleeve 51 are controlled by the adjusting screw 4 to adjust The first rack 32 is provided with a first meshing tooth 321, the second rack 52 is provided with a second meshing tooth 521, the adjusting screw 4 is provided with a third meshing tooth 41, the third meshing tooth 41 is meshed with the first meshing tooth 321 and the second meshing tooth 521 at the same time, and the first sleeve 31 and the second sleeve 51 can be simultaneously extended outward or retracted inward by rotating the adjusting screw 4, the inner circumferential side surfaces of the first sleeve 31 and the second sleeve 51 are both covered with a buffer rubber pad 6, and the maximum outward extension length of the first sleeve 31 and the second sleeve 51 is 50 mm.

[0029] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the attached claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved.

[0030] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A multi-stage optical fiber amplifier, characterized in that: It includes a pump laser, a signal pump beam combiner, and an optical fiber, wherein the pump laser is used to output pump light, and the signal pump beam combiner is used to couple the input signal light and the pump light into the optical fiber; The optical fiber is a double-clad optical fiber, comprising an optical fiber core, an inner cladding, an outer cladding and a protective layer. The optical fiber core is doped with the rare earth element SiO2, which serves as the main transmission channel of the laser. The corresponding wavelength is designed to be single-mode, and the output laser is the fundamental transverse mode; The diameter of the inner cladding is greater than the diameter of the outer cladding, the inner cladding is used to transmit pump light, and the pump laser adopts a multi-mode pump source, and outputs pump light through the multi-mode pump source to achieve output of high power and pulse energy; The outer cladding is composed of a polymer material, and its refractive index is less than that of the inner cladding; The protective layer is made of hard plastic and is used to protect the optical fiber; The pump light is transmitted through the inner cladding, and the pump light excites the rare earth element SiO2 doped in the optical fiber core, thereby achieving amplification of the optical signal.

2. A multi-stage optical fiber amplifier according to claim 1, characterized in that: The pump light is transmitted through the inner cladding.

3. A multi-stage optical fiber amplifier according to claim 2, characterized in that: The optical fiber core is also doped with rare earth elements, and the optical signal can be amplified by doping with rare earth elements.

4. A multi-stage optical fiber amplifier according to claim 3, characterized in that: The pump laser, the signal pump combiner, and the optical fiber are all placed in a containing box, and the containing box is used to ensure the stability of the optical fiber inlet and outlet ports. The containing box includes an upper cover body and a lower cover body that cover each other, and the upper cover body is provided with a first groove, and the lower cover body is provided with a second groove. When the upper cover body and the lower cover body cover each other, the first groove and the second groove cooperate with each other to form an entrance and an exit for the optical fiber to enter and exit.

5. A multi-stage optical fiber amplifier according to claim 4, characterized in that: An auxiliary supporting device for enhancing the supporting stability of the optical fiber and the port of the accommodating box is provided in the accommodating box, and the auxiliary supporting device includes a first supporting connecting member, a second supporting connecting member, and an adjusting screw. The adjusting screw and the first supporting connecting member are mutually connected, and the adjusting screw and the second supporting connecting member are mutually connected. The horizontal movement of the first supporting connecting member and the second supporting connecting member is controlled by the rotation of the adjusting screw.

6. A multi-stage optical fiber amplifier according to claim 5, characterized in that: A first support block and a second support block are arranged in the accommodating box, and the first support block and the second support block are respectively arranged at the inlet and the outlet to provide placement space for the first supporting connector and the second supporting connector, and the first support block and the second support block are fixedly connected to the accommodating box.

7. A multi-stage optical fiber amplifier according to claim 6, characterized in that: The first supporting connection member and the second supporting connection member have the same structure. The first supporting connection member includes a first sleeve and a first rack that are fixedly connected. The second supporting connection member includes a second sleeve and a second rack that are fixedly connected. The first sleeve is placed on the first supporting block and extends outward through the inlet. The second sleeve is placed on the second supporting block and extends outward through the outlet. The outward extension distance of the first sleeve and the second sleeve is controlled by the adjusting screw.

8. A multi-stage optical fiber amplifier according to claim 7, characterized in that: The first rack is provided with a first meshing tooth, the second rack is provided with a second meshing tooth, and the adjusting screw is provided with a third meshing tooth. The third meshing tooth meshes with the first meshing tooth and the second meshing tooth at the same time. By rotating the adjusting screw, the first sleeve and the second sleeve can be extended outward at the same time or retracted inward at the same time.

9. A multi-stage optical fiber amplifier according to claim 8, characterized in that: The inner circumferential side surfaces of the first sleeve and the second sleeve are both covered with buffer rubber pads.

10. The multi-stage optical fiber amplifier according to claim 9, characterized in that: The maximum outward extension length of the first sleeve and the second sleeve is 50 mm.

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