A gain optical fiber for extending L-band amplification bandwidth and a preparation method thereof

Abstract

The invention provides a gain optical fiber for extending L-band amplification bandwidth and a preparation method thereof. The gain optical fiber for extending L-band amplification bandwidth comprises a core layer, an inner cladding layer, an outer cladding layer and a coating layer which are sequentially arranged from the inside to the outside in radial direction. The core layer consists of the following components in molar percentage: 0.01-0.1 mol% Er2O3, 0.1-1 mol% Yb2O3, 9-20 mol% P2O5, 2-10 mol% Al2O3, and the remainder is SiO2. The gain optical fiber for extending L-band amplification bandwidth provided by the invention optimizes the doping process of the core layer, and dopes erbium, ytterbium, phosphorus and aluminum in the core layer. Meanwhile, by adjusting the ratio of phosphorus and aluminum, the L-band gain bandwidth of the gain optical fiber is effectively extended. A double cladding structure design is adopted, and the pump cost of the prepared optical fiber amplifier is greatly reduced.

Description

Technical Field

[0001] The present invention relates to the field of gain optical fibers, and in particular to a gain optical fiber for extending L-band amplification bandwidth and a preparation method thereof. Background Art

[0002] With the rapid development of technologies such as big data, 5G / 6G, and intelligent computing, the capacity of optical fiber communications urgently needs to be further expanded. The bandwidth of optical fiber communications is mainly limited by the gain bandwidth of the optical fiber amplifier. The key lies in the amplification bandwidth that the gain fiber can achieve. Erbium-ytterbium co-doped fiber has the significant advantages of high pump conversion efficiency and low pump cost. According to previous studies, phosphorus has the ability to regulate Er. 3+ The important role of luminescence is one of the key elements to achieve L-band expansion and amplification of erbium-doped fiber. Erbium-ytterbium co-doped fiber often uses high phosphorus doping process to enhance Yb 3+ Xiang Er 3+ The energy transfer efficiency is improved to obtain high-performance Er-Yb co-doped optical fiber. However, due to the signal excited state absorption effect, high phosphorus doping will also cause the long-wave gain of the optical fiber to decrease rapidly, which is not conducive to further expanding the L-band gain.

[0003] Therefore, there is an urgent need for a gain optical fiber that extends the L-band amplification bandwidth and a preparation method thereof to solve the above technical problems. Summary of the invention

[0004] The purpose of the present invention is to provide a gain optical fiber with extended L-band amplification bandwidth and a preparation method thereof, so as to improve the technical problem that the erbium-ytterbium co-doped optical fiber in the prior art is difficult to further extend the L-band gain.

[0005] In order to solve the above technical problems, the present invention first provides a gain optical fiber for extending the L-band amplification bandwidth, comprising a core layer, an inner cladding layer, an outer cladding layer and a coating layer arranged in sequence from the inside to the outside along the radial direction, and the core layer is composed of the following components in molar percentage: 0.01-0.1 mol% Er2O3, 0.1-1 mol% Yb2O3, 9-20 mol% P2O5, 2-10 mol% Al2O3, and the remainder is SiO2.

[0006] Preferably, the refractive index of the core layer is greater than that of the inner cladding, the refractive index of the inner cladding is greater than that of the outer cladding, and the refractive index of the outer cladding is greater than that of the coating layer.

[0007] Preferably, the material of the inner cladding layer is SiO2, and the material of the outer cladding layer is any one of polyacrylate, polyimide and fluorine-doped SiO2.

[0008] Preferably, the cross section of the inner cladding is any one of a regular octagon, a plum blossom, a D-shape and a regular hexagon.

[0009] Accordingly, the present invention also provides a method for preparing a gain optical fiber for extending L-band amplification bandwidth as described in any one of the above items, the method comprising:

[0010] S10, depositing on the inner wall of a substrate tube to form a loose layer;

[0011] S20, remove the substrate tube and soak it until it contains Er 3+ , Yb 3+ and Al 3+ The doping solution is immersed in the porous layer, and the loose layer is dried and oxidized in sequence to form an oxidation reaction tube;

[0012] S30, performing phosphorus deposition and sintering treatment on the oxidation reaction tube to form a mother rod;

[0013] S40, performing a collapse and sintering process on the mother rod to form an optical fiber preform rod including a core layer;

[0014] S50, performing a casing process on the optical fiber preform rod after testing according to a fixed core-to-cladding ratio to form a casing rod, wherein the casing rod includes an inner cladding;

[0015] S60, drawing and coating the sleeve rod respectively to obtain a gain optical fiber with an extended L-band amplification bandwidth including a coating layer.

[0016] Preferably, step S10 specifically includes:

[0017] The loose layer is deposited on the inner wall of the substrate tube by the MCVD process, wherein the deposition gas used in the MCVD process is SiCl4 and the deposition temperature is 1400°C.

[0018] Preferably, in step S20, the drying gas used to dry the loose layer is Cl2, and the drying temperature is 900°C; the oxidizing gas used to oxidize the loose layer is O2, and the oxidation temperature is 1300°C.

[0019] Preferably, in step S30, the loose layer is subjected to phosphorus deposition and sintering treatment using POCl3 and O2, and the sintering temperature is 1400°C.

[0020] Preferably, in step S40, the core layer is composed of the following components in molar percentage: 0.01-0.1 mol% Er2O3, 0.1-1 mol% Yb2O3, 9-20 mol% P2O5, 2-10 mol% Al2O3, and the remainder is SiO2.

[0021] Preferably, in step S50, the cross section of the inner cladding is any one of a regular octagon, a quincunx shape, a D shape and a regular hexagon.

[0022] The beneficial effects of the present invention are as follows: Different from the prior art, the present invention provides a gain optical fiber with extended L-band amplification bandwidth and a preparation method thereof, wherein the gain optical fiber with extended L-band amplification bandwidth comprises a core layer, an inner cladding layer, an outer cladding layer and a coating layer which are arranged in sequence from the inside to the outside along the radial direction, and the core layer is composed of the following components in molar percentage: 0.01-0.1 mol% Er2O3, 0.1-1 mol% Yb2O3, 9-20 mol% P2O5, 2-10 mol% Al2O3, and the remainder is SiO2; the gain optical fiber with extended L-band amplification bandwidth provided by the present invention optimizes the doping process of the core layer, and erbium, ytterbium, phosphorus and aluminum are doped in the core layer, and at the same time, the L-band gain bandwidth of the gain optical fiber is effectively extended by adjusting the ratio of phosphorus and aluminum, and a double cladding structure design is adopted, which greatly reduces the pump cost of the prepared optical fiber amplifier. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram of the end face of a gain optical fiber for extending L-band amplification bandwidth provided by an embodiment of the present invention;

[0024] Figure 2 A flow chart of a method for preparing a gain optical fiber with extended L-band amplification bandwidth provided by an embodiment of the present invention;

[0025] Figure 3 A schematic diagram of a test optical path structure for an application of a gain optical fiber for extending L-band amplification bandwidth provided by an embodiment of the present invention;

[0026] Figure 4 Schematic diagram of detection results of 10 dB gain wavelength corresponding to optical path testing in different embodiments of the present invention;

[0027] Figure 5 Schematic diagram of the detection results of optical fiber corrugations corresponding to the optical path test according to different embodiments of the present invention. DETAILED DESCRIPTION

[0028] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] See also Figure 1 , Figure 1The end face diagram of the gain optical fiber 10 for extending the L-band amplification bandwidth provided by an embodiment of the present invention is shown; wherein the gain optical fiber 10 for extending the L-band amplification bandwidth comprises a core layer 11, an inner cladding layer 12, an outer cladding layer 13 and a coating layer 14 arranged in sequence from the inside to the outside along the radial direction, and the core layer 11 is composed of the following components in molar percentage:

[0030] 0.01~0.1mol% Er2O3, 0.1~1mol% Yb2O3, 9~20mol% P2O5, 2~10mol% Al2O3, and the balance is SiO2.

[0031] In the embodiment of the present invention, the core layer 11 is used to absorb the pump light and convert it into laser light.

[0032] Specifically, Er 3+ The main function is to amplify L-band and L-band extended band signals; Yb 3+ The main function of the ion is to absorb the pump light and transfer the energy to Er 3+ ; The main function of P2O5 is to enhance the 3+ Xiang Er 3+ The energy transfer efficiency of P2O5 is very high, and P2O5 can regulate the expansion of rare earth electron cloud. 3+ The absorption emission peak is red-shifted to around 1535nm, and the small signal gain in the 1610-1630nm band is made flatter, thus greatly expanding the gain of the optical fiber in the L-band; Al2O3 can adjust Er 3 + The degree of energy level broadening is manifested in the increase of the gain of longer waves in the gain spectrum, while the gain of short-wave positions does not decrease much.

[0033] In the embodiment of the present invention, the inner cladding 12 is composed of SiO2 and is mainly used for transmitting pump light; the material of the outer cladding 13 is any one of polyacrylate, polyimide and fluorine-doped SiO2; and the coating layer 14 is composed of acrylic resin.

[0034] Specifically, the refractive index of the core layer 11 is greater than that of the inner cladding 12, the refractive index of the inner cladding 12 is greater than that of the outer cladding 13, and the refractive index of the outer cladding 13 is greater than that of the coating 14; wherein the optical waveguide structure formed by the refractive index difference between the inner cladding 12 and the coating 14 can realize the transmission of the pump light in the inner cladding 12. The outer cladding 13 uses low-refractive-index organic optical fiber coatings (polyacrylate, polyimide, etc.) or inorganic fluorine-doped quartz glass, ensuring that low-cost 915-980nm multimode laser diodes can be used as pump sources, greatly reducing the pumping cost of the optical fiber amplifier.

[0035] Furthermore, the cross-section of the inner cladding 12 is any one of a regular octagon, a plum blossom, a D-shape and a regular hexagon; wherein, this structure of the inner cladding 12 can improve the absorption efficiency of the pump light; when the pump light is transmitted in the optical fiber, if the inner cladding 12 is a circular structure, a large amount of light will bypass the core layer 11 in a spiral manner, so that the pump absorption efficiency will be very low. The inner cladding 12 adopts a non-circular structure such as a regular octagon, which can increase the chance of the pump light passing through the core layer 11, thereby improving the pump absorption efficiency.

[0036] Accordingly, see Figure 2 The embodiment of the present invention further provides a method for preparing a gain fiber 10 for extending an L-band amplification bandwidth. The method for preparing a gain fiber 10 for extending an L-band amplification bandwidth comprises the following steps:

[0037] S10, depositing a loose layer on the inner wall of a substrate tube.

[0038] S20, remove the substrate tube and soak it until it contains Er 3+ , Yb 3+ and Al 3+ The doping solution is immersed in the porous layer, and the loose layer soaked in the doping solution is dried and oxidized in sequence to form an oxidation reaction tube.

[0039] S30, performing phosphorus deposition and sintering treatment on the oxidation reaction tube to form a mother rod.

[0040] S40, performing a collapse and sintering process on the mother rod to form an optical fiber preform rod including a core layer 11.

[0041] S50 , after being tested, the optical fiber preform rod is subjected to casing treatment according to a fixed core-to-cladding ratio to form a casing rod, wherein the casing rod includes an inner cladding 12 .

[0042] S60 , drawing and coating the sleeve rod respectively to obtain a gain optical fiber 10 with an extended L-band amplification bandwidth and a coating layer 14 .

[0043] Preferably, step S10 specifically includes:

[0044] A loose layer is deposited on the inner wall of the substrate tube by the MCVD (Modified Chemical Vapor Deposition) process, wherein the deposition gas used in the MCVD process is SiCl4 and the deposition temperature is 1400°C.

[0045] Preferably, in step S20, the drying gas used to dry the loose layer is Cl2, and the drying temperature is 900°C; the oxidizing gas used to oxidize the loose layer is O2, and the oxidation temperature is 1300°C.

[0046] Preferably, in step S30, the loose layer is subjected to phosphorus deposition and sintering treatment using POCl3 and O2, and the sintering temperature is 1400°C.

[0047] Preferably, in step S40, the core layer 11 is composed of the following components in molar percentage: 0.01-0.1 mol% Er2O3, 0.1-1 mol% Yb2O3, 9-20 mol% P2O5, 2-10 mol% Al2O3, and the remainder is SiO2.

[0048] Preferably, in step S50, the cross section of the inner cladding 12 is any one of a regular octagon, a quincunx shape, a D shape and a regular hexagon.

[0049] The technical solution of the present application is now described in conjunction with specific embodiments.

[0050] Embodiment 1:

[0051] Embodiment 1 of the present invention provides a gain optical fiber 10 for extending L-band amplification bandwidth; wherein the gain optical fiber 10 for extending L-band amplification bandwidth comprises a core layer 11, an inner cladding layer 12, an outer cladding layer 13 and a coating layer 14 arranged in sequence from the inside to the outside along the radial direction, and the core layer 11 is composed of the following components in molar percentage:

[0052] The concentration of Er2O3 is 0.01 mol%, the concentration of Yb2O3 is 0.1 mol%, the concentration of Al2O3 is 2 mol%, the concentration of P2O5 is 9 mol%, and the concentration of SiO2 is 89.89 mol%.

[0053] Accordingly, Embodiment 1 of the present invention further provides a method for preparing a gain optical fiber 10 for extending an L-band amplification bandwidth. The method for preparing a gain optical fiber 10 for extending an L-band amplification bandwidth comprises the following steps:

[0054] Step 1: Deposit a loose layer of SiO2 material on the inner wall of a quartz substrate tube using the MCVD process: introduce 100 sccm of SiCl4 into the quartz tube, the deposition temperature is 1400°C, the main lamp translation speed is 50 mm / min, and the rotation speed is 20 rpm;

[0055] Step 2: First, immerse the substrate tube with the loose layer deposited thereon in a doping solution, wherein the doping solution includes Er 3+ , Yb 3 + and Al 3+; The solute in the doping solution has a concentration of ErCl3 of 0.004 mol / L, a concentration of YbCl3 of 0.04 mol / L, and a concentration of AlCl3 of 0.8 mol / L; secondly, the substrate tube is immersed for 1.5 hours, the solution is extracted and dried to obtain a doped quartz tube;

[0056] Step 3, reinstall the above doped quartz tube onto the MCVD lathe, introduce 200 sccmCl2 for drying, the drying temperature is 900°C, the main lamp translation speed is 50 mm / min, the rotation speed is 20 rpm, and the residual hydroxyl groups are removed to obtain a reaction tube;

[0057] Step 4: After the reaction tube is dried, 200 sccmO2 is introduced at high temperature, the oxidation temperature is 1300°C, the main lamp translation speed is 50 mm / min, and the rotation speed is 20 rpm to carry out oxidation reaction to obtain an oxidation reaction tube;

[0058] Step 5: 200 sccm POCl3 and 800 sccm O2 are introduced into the oxidation reaction tube for phosphorus deposition and sintering. The sintering temperature is 1400°C, the main lamp translation speed is 50 mm / min, and the rotation speed is 20 rpm to obtain a mother rod;

[0059] Step 6, collapsing and burning the mother rod into an optical fiber preform;

[0060] Step seven, insert the optical fiber preform rod into the quartz sleeve, and use the tube-rod method to draw it into a double-clad erbium-ytterbium co-doped optical fiber with a core diameter of 6 μm and a cladding diameter of 125 μm.

[0061] Embodiment 2:

[0062] The structure of the gain fiber 10 for extending the L-band amplification bandwidth provided in Example 2 of the present invention is substantially the same as that of the gain fiber 10 for extending the L-band amplification bandwidth provided in Example 1 of the present invention, except that the material of the core layer 11 is different.

[0063] Specifically, the core layer 11 of the gain optical fiber 10 for extending the L-band amplification bandwidth provided in Embodiment 2 of the present invention is composed of the following components in terms of molar percentage:

[0064] The concentration of Er2O3 is 0.1 mol%, the concentration of Yb2O3 is 1 mol%, the concentration of Al2O3 is 2 mol%, the concentration of P2O5 is 9 mol%, and the concentration of SiO2 is 87.9 mol%.

[0065] Accordingly, the method for preparing the gain fiber 10 with extended L-band amplification bandwidth provided in Example 2 of the present invention is substantially the same as the method for preparing the gain fiber 10 with extended L-band amplification bandwidth provided in Example 1 of the present invention, the only difference being that the doping solution selected in step 2 is different.

[0066] Specifically, step 2 of the method for preparing the gain optical fiber 10 with extended L-band amplification bandwidth provided by Embodiment 2 of the present invention specifically includes:

[0067] First, the substrate tube with the loose layer deposited thereon is immersed in a doping solution, which includes Er 3+ , Yb 3+ and Al 3+ ; In the solute of the doping solution: the concentration of ErCl3 is 0.04mol / L, the concentration of YbCl3 is 0.4mol / L, and the concentration of AlCl3 is 0.8mol / L; secondly, after soaking the substrate tube for 1.5h, the solution is drained and blown dry to obtain a doped quartz tube.

[0068] Embodiment 3:

[0069] The structure of the gain fiber 10 for extending the L-band amplification bandwidth provided in Example 3 of the present invention is substantially the same as that of the gain fiber 10 for extending the L-band amplification bandwidth provided in Example 1 of the present invention, except that the material of the core layer 11 is different.

[0070] Specifically, the core layer 11 of the gain optical fiber 10 for extending the L-band amplification bandwidth provided by Embodiment 3 of the present invention is composed of the following components in terms of molar percentage:

[0071] The concentration of Er2O3 is 0.1 mol%, the concentration of Yb2O3 is 1 mol%, the concentration of Al2O3 is 10 mol%, the concentration of P2O5 is 9 mol%, and the concentration of SiO2 is 79.9 mol%.

[0072] Accordingly, the method for preparing the gain fiber 10 with extended L-band amplification bandwidth provided in Example 3 of the present invention is substantially the same as the method for preparing the gain fiber 10 with extended L-band amplification bandwidth provided in Example 1 of the present invention, the only difference being that the doping solution selected in step 2 is different.

[0073] Specifically, step 2 of the method for preparing the gain optical fiber 10 with extended L-band amplification bandwidth provided by embodiment 3 of the present invention specifically includes:

[0074] First, the substrate tube with the loose layer deposited thereon is immersed in a doping solution, which includes Er 3+ , Yb 3+ and Al 3+ ; In the solute of the doping solution: the concentration of ErCl3 is 0.04mol / L, the concentration of YbCl3 is 0.4mol / L, and the concentration of AlCl3 is 4mol / L; secondly, after soaking the substrate tube for 1.5h, the solution is drained and blown dry to obtain a doped quartz tube.

[0075] Embodiment 4:

[0076] The structure of the gain fiber 10 for extending the L-band amplification bandwidth provided in Example 4 of the present invention is substantially the same as the structure of the gain fiber 10 for extending the L-band amplification bandwidth provided in Example 1 of the present invention, and the only difference is that the material of the core layer 11 is different.

[0077] Specifically, the core layer 11 of the gain optical fiber 10 for extending the L-band amplification bandwidth provided by Embodiment 4 of the present invention is composed of the following components in terms of molar percentage:

[0078] The concentration of Er2O3 is 0.1 mol%, the concentration of Yb2O3 is 1 mol%, the concentration of Al2O3 is 2 mol%, the concentration of P2O5 is 20 mol%, and the concentration of SiO2 is 76.9 mol%.

[0079] Accordingly, the preparation method of the gain fiber 10 with extended L-band amplification bandwidth provided in Example 4 of the present invention is substantially the same as the preparation method of the gain fiber 10 with extended L-band amplification bandwidth provided in Example 1 of the present invention, the only difference being that the doping solution selected in step 2 is different, and the amount of POCl3 used in step 5 is different.

[0080] Specifically, step 2 of the method for preparing the gain optical fiber 10 with extended L-band amplification bandwidth provided by embodiment 4 of the present invention specifically includes:

[0081] First, the substrate tube with the loose layer deposited thereon is immersed in a doping solution, which includes Er 3+ , Yb 3+ and Al 3+ ; In the solute of the doping solution: the concentration of ErCl3 is 0.04mol / L, the concentration of YbCl3 is 0.4mol / L, and the concentration of AlCl3 is 0.8mol / L; secondly, after soaking the substrate tube for 1.5h, the solution is drained and blown dry to obtain a doped quartz tube.

[0082] Specifically, step 5 of the method for preparing the gain optical fiber 10 with extended L-band amplification bandwidth provided by embodiment 4 of the present invention specifically includes:

[0083] 400 sccm POCl3 and 800 sccm O2 were introduced into the oxidation reaction tube for phosphorus deposition and sintering. The sintering temperature was 1400°C, the main lamp translation speed was 50 mm / min, and the rotation speed was 20 rpm to obtain a mother rod.

[0084] Embodiment 5:

[0085] The structure of the gain fiber 10 for extending the L-band amplification bandwidth provided in Example 5 of the present invention is substantially the same as that of the gain fiber 10 for extending the L-band amplification bandwidth provided in Example 1 of the present invention, except that the material of the core layer 11 is different.

[0086] Specifically, the core layer 11 of the gain optical fiber 10 for extending the L-band amplification bandwidth provided by Embodiment 5 of the present invention is composed of the following components in terms of molar percentage:

[0087] The concentration of Er2O3 is 0.1 mol%, the concentration of Yb2O3 is 1 mol%, the concentration of Al2O3 is 10 mol%, the concentration of P2O5 is 20 mol%, and the concentration of SiO2 is 68.9 mol%.

[0088] Accordingly, the preparation method of the gain fiber 10 with extended L-band amplification bandwidth provided in Example 5 of the present invention is substantially the same as the preparation method of the gain fiber 10 with extended L-band amplification bandwidth provided in Example 1 of the present invention, the only difference being that the doping solution selected in step 2 is different, and the amount of POCl3 used in step 5 is different.

[0089] Specifically, step 2 of the method for preparing the gain optical fiber 10 with extended L-band amplification bandwidth provided by Embodiment 5 of the present invention specifically includes:

[0090] First, the substrate tube with the loose layer deposited thereon is immersed in a doping solution, which includes Er 3+ , Yb 3+ and Al 3+ ; In the solute of the doping solution: the concentration of ErCl3 is 0.04mol / L, the concentration of YbCl3 is 0.4mol / L, and the concentration of AlCl3 is 4mol / L; secondly, after soaking the substrate tube for 1.5h, the solution is drained and blown dry to obtain a doped quartz tube.

[0091] Specifically, step 5 of the method for preparing the gain optical fiber 10 with extended L-band amplification bandwidth provided by embodiment 5 of the present invention specifically includes:

[0092] 400 sccm POCl3 and 800 sccm O2 were introduced into the oxidation reaction tube for phosphorus deposition and sintering. The sintering temperature was 1400°C, the main lamp translation speed was 50 mm / min, and the rotation speed was 20 rpm to obtain a mother rod.

[0093] Embodiment 6:

[0094] The structure of the gain fiber 10 for extending the L-band amplification bandwidth provided in Example 6 is substantially the same as the structure of the gain fiber 10 for extending the L-band amplification bandwidth provided in Example 1 of the present invention, and the only difference is that the material of the core layer 11 is different.

[0095] Specifically, the core layer 11 of the gain optical fiber 10 for extending the L-band amplification bandwidth provided in Example 6 is composed of the following components in terms of molar percentage:

[0096] The concentration of Er2O3 is 0.1 mol%, the concentration of Yb2O3 is 1 mol%, the concentration of Al2O3 is 2 mol%, the concentration of P2O5 is 8 mol%, and the concentration of SiO2 is 88.9 mol%.

[0097] Accordingly, the preparation method of the gain fiber 10 with extended L-band amplification bandwidth provided in Example 6 is substantially the same as the preparation method of the gain fiber 10 with extended L-band amplification bandwidth provided in Example 1, with the only difference being that the doping solution selected in step 2 is different and the amount of POCl3 used in step 5 is different.

[0098] Specifically, step 2 of the method for preparing the gain optical fiber 10 with extended L-band amplification bandwidth provided in Example 6 specifically includes:

[0099] First, the substrate tube with the loose layer deposited thereon is immersed in a doping solution, which includes Er 3+ , Yb 3+ and Al 3+ ; In the solute of the doping solution: the concentration of ErCl3 is 0.04mol / L, the concentration of YbCl3 is 0.4mol / L, and the concentration of AlCl3 is 0.8mol / L; secondly, after soaking the substrate tube for 1.5h, the solution is drained and blown dry to obtain a doped quartz tube.

[0100] Specifically, step 5 of the method for preparing the gain optical fiber 10 with extended L-band amplification bandwidth provided in Example 6 specifically includes:

[0101] 160 sccm POCl3 and 800 sccm O2 were introduced into the oxidation reaction tube for phosphorus deposition and sintering. The sintering temperature was 1400°C, the main lamp translation speed was 50 mm / min, and the rotation speed was 20 rpm to obtain a mother rod.

[0102] Embodiment 7:

[0103] The structure of the gain fiber 10 for extending the L-band amplification bandwidth provided in Example 7 is substantially the same as the structure of the gain fiber 10 for extending the L-band amplification bandwidth provided in Example 1 of the present invention, and the only difference is that the material of the core layer 11 is different.

[0104] Specifically, the core layer 11 of the gain optical fiber 10 for extending the L-band amplification bandwidth provided in Example 7 is composed of the following components in molar percentage:

[0105] The concentration of Er2O3 is 0.1 mol%, the concentration of Yb2O3 is 1 mol%, the concentration of Al2O3 is 2 mol%, the concentration of P2O5 is 21 mol%, and the concentration of SiO2 is 75.9 mol%.

[0106] Accordingly, the preparation method of the gain fiber 10 with extended L-band amplification bandwidth provided in Example 7 is substantially the same as the preparation method of the gain fiber 10 with extended L-band amplification bandwidth provided in Example 1 of the present invention, with the only difference being that the doping solution selected in step 2 is different and the amount of POCl3 used in step 5 is different.

[0107] Specifically, step 2 of the method for preparing the gain optical fiber 10 with extended L-band amplification bandwidth provided in Example 7 specifically includes:

[0108] First, the substrate tube with the loose layer deposited thereon is immersed in a doping solution, which includes Er 3+ , Yb 3+ and Al 3+ ; In the solute of the doping solution: the concentration of ErCl3 is 0.04mol / L, the concentration of YbCl3 is 0.4mol / L, and the concentration of AlCl3 is 0.8mol / L; secondly, after soaking the substrate tube for 1.5h, the solution is drained and blown dry to obtain a doped quartz tube.

[0109] Specifically, step 5 of the method for preparing the gain optical fiber 10 with extended L-band amplification bandwidth provided in Example 7 specifically includes:

[0110] 420 sccm POCl3 and 800 sccm O2 were introduced into the oxidation reaction tube for phosphorus deposition and sintering. The sintering temperature was 1400°C, the main lamp translation speed was 50 mm / min, and the rotation speed was 20 rpm to obtain a mother rod.

[0111] Embodiment 8:

[0112] The structure of the gain fiber 10 for extending the L-band amplification bandwidth provided in Example 8 is substantially the same as the structure of the gain fiber 10 for extending the L-band amplification bandwidth provided in Example 1 of the present invention, and the only difference is that the material of the core layer 11 is different.

[0113] Specifically, the core layer 11 of the gain optical fiber 10 for extending the L-band amplification bandwidth provided in Example 8 is composed of the following components in molar percentage:

[0114] The concentration of Er2O3 is 0.1 mol%, the concentration of Yb2O3 is 1 mol%, the concentration of Al2O3 is 1 mol%, the concentration of P2O5 is 20 mol%, and the concentration of SiO2 is 77.9 mol%.

[0115] Accordingly, the preparation method of the gain fiber 10 with extended L-band amplification bandwidth provided in Example 8 is substantially the same as the preparation method of the gain fiber 10 with extended L-band amplification bandwidth provided in Example 1 of the present invention, with the only difference being that the doping solution selected in step 2 is different and the amount of POCl3 used in step 5 is different.

[0116] Specifically, step 2 of the method for preparing the gain optical fiber 10 with extended L-band amplification bandwidth provided in Example 8 specifically includes:

[0117] First, the substrate tube with the loose layer deposited thereon is immersed in a doping solution, which includes Er 3+ , Yb 3+ and Al 3+ ; In the solute of the doping solution: the concentration of ErCl3 is 0.04mol / L, the concentration of YbCl3 is 0.4mol / L, and the concentration of AlCl3 is 0.4mol / L; secondly, after soaking the substrate tube for 1.5h, the solution is drained and blown dry to obtain a doped quartz tube.

[0118] Specifically, step 5 of the method for preparing the gain optical fiber 10 with extended L-band amplification bandwidth provided in Example 8 specifically includes:

[0119] 400 sccm POCl3 and 800 sccm O2 were introduced into the oxidation reaction tube for phosphorus deposition and sintering. The sintering temperature was 1400°C, the main lamp translation speed was 50 mm / min, and the rotation speed was 20 rpm to obtain a mother rod.

[0120] Embodiment 9:

[0121] The structure of the gain fiber 10 for extending the L-band amplification bandwidth provided in Example 9 is substantially the same as the structure of the gain fiber 10 for extending the L-band amplification bandwidth provided in Example 1 of the present invention, and the only difference is that the material of the core layer 11 is different.

[0122] Specifically, the core layer 11 of the gain optical fiber 10 for extending the L-band amplification bandwidth provided in Example 9 is composed of the following components in terms of molar percentage:

[0123] The concentration of Er2O3 is 0.1 mol%, the concentration of Yb2O3 is 1 mol%, the concentration of Al2O3 is 12 mol%, the concentration of P2O5 is 20 mol%, and the concentration of SiO2 is 66.9 mol%.

[0124] Accordingly, the preparation method of the gain fiber 10 with extended L-band amplification bandwidth provided in Example 9 is substantially the same as the preparation method of the gain fiber 10 with extended L-band amplification bandwidth provided in Example 1 of the present invention, with the only difference being that the doping solution selected in step 2 is different and the amount of POCl3 used in step 5 is different.

[0125] Specifically, step 2 of the method for preparing the gain optical fiber 10 with extended L-band amplification bandwidth provided in Example 9 specifically includes:

[0126] First, the substrate tube with the loose layer deposited thereon is immersed in a doping solution, which includes Er 3+ , Yb 3+ and Al 3+ ; In the solute of the doping solution: the concentration of ErCl3 is 0.04mol / L, the concentration of YbCl3 is 0.4mol / L, and the concentration of AlCl3 is 4.8mol / L; secondly, after soaking the substrate tube for 1.5h, the solution is drained and blown dry to obtain a doped quartz tube.

[0127] Specifically, step 5 of the method for preparing the gain optical fiber 10 with extended L-band amplification bandwidth provided in Example 9 specifically includes:

[0128] 400 sccm POCl3 and 800 sccm O2 were introduced into the oxidation reaction tube for phosphorus deposition and sintering. The sintering temperature was 1400°C, the main lamp translation speed was 50 mm / min, and the rotation speed was 20 rpm to obtain a mother rod.

[0129] Specifically, the above-mentioned 9 gain optical fibers 10 with extended L-band amplification bandwidth are subjected to optical path testing, and the obtained test optical path structure 20 is as follows: Figure 3 As shown, Figure 3 A schematic diagram of a test optical path structure 20 applied to a gain optical fiber 10 for extending L-band amplification bandwidth provided by an embodiment of the present invention.

[0130] In the embodiment of the present invention, the test optical path structure 20 comprises a seed signal light source 21, a first isolator 22, a first wavelength division multiplexer 23, a gain fiber 10 for extending the L-band amplification bandwidth, a second wavelength division multiplexer 24 and a second isolator 25 which are coaxially arranged in sequence.

[0131] Specifically, the seed signal light source 21 is used to generate seed signal light, which has low power but good quality, and is used for subsequent power amplification.

[0132] Specifically, the first isolator 22 is a passive optical isolator device that only allows unidirectional light to pass through, and its working principle is based on the non-reciprocity of Faraday rotation. The first isolator 22 is a passive device that allows light to pass through in one direction but prevents it from passing through in the opposite direction. Its function is to limit the direction of light so that light can only be transmitted in one direction. The light reflected by the optical fiber echo can be well isolated by the first isolator 22, thereby improving the light wave transmission efficiency.

[0133] In an embodiment of the present invention, the first isolator 22 is coupled to the rear end of the seed signal light source 21, and its wavelength range covers the range of the seed signal light source 21; the first isolator 22 allows the seed signal light to pass through the seed signal light source 21, while preventing the backward light generated by the test optical path structure 20 and the end face reflection from damaging the seed signal light source 21, thereby protecting the system components.

[0134] In the embodiment of the present invention, the first port of the first wavelength division multiplexer 23 is connected to the first multimode pump source 26, the second port of the first wavelength division multiplexer 23 is connected to the first isolator 22, and the third port of the first wavelength division multiplexer 23 is connected to the first end of the gain optical fiber 10 that extends the L-band amplification bandwidth; wherein, the first wavelength division multiplexer 23 is a technology that combines two or more optical carrier signals of different wavelengths (carrying various information) at the transmitting end and couples them to the same optical fiber of the optical line for transmission.

[0135] In the embodiment of the present invention, the gain fiber 10 with extended L-band amplification bandwidth is used as a gain medium. When light is incident on the gain fiber 10 with extended L-band amplification bandwidth, the energy carried by the incident light excites the electrons in the medium to a higher energy level due to the absorption of the medium. Through the relaxation phenomenon, the electrons transition from the high energy level to the ground state to release energy and emit photons.

[0136] In an embodiment of the present invention, the first port of the second wavelength division multiplexer 24 is connected to the second end of the gain optical fiber 10 that extends the L-band amplification bandwidth, the second port of the second wavelength division multiplexer 24 is connected to the second multimode pump source 26, and the third port of the second wavelength division multiplexer 24 is connected to the second isolator 25.

[0137] Specifically, the test optical path structure 20 prepared by the above-mentioned 9 gain optical fibers 10 with extended L-band amplification bandwidth corresponds to the 10 dB gain wavelength and the detection results of the optical fiber corrugation. Figures 4 to 5 shown. Figure 4 Schematic diagram of the detection results of the 10dB gain wavelength corresponding to the optical path test of different embodiments of the present invention ( Figure 4 In the figure, the horizontal axis is the serial number of the embodiment, and the vertical axis is the gain wavelength); Figure 5 Schematic diagram of the detection results of optical fiber corrugations corresponding to the optical path test of different embodiments of the present invention ( Figure 5 In the figure, the horizontal axis is the serial number of the embodiment, and the vertical axis is the ripple).

[0138] Furthermore, the specific test results of the test optical path structure 20 prepared by the above-mentioned different gain optical fibers 10 are shown in the following Table 1:

[0139] Table 1 Specific test results of the test optical path structure 20 prepared with different gain optical fibers 10

[0140] Example <![CDATA[Er2O3]]> <![CDATA[Yb2O3]]> <![CDATA[Al2O3]]> <![CDATA[P2O5]]> <![CDATA[SiO2]]> 10dB gain wavelength / nm Ripple / dB Example 1 0.01 0.1 2 9 89.89 1627.1 10.55 Example 2 0.1 1 2 9 87.9 1627.2 10.56 Example 3 0.1 1 10 9 79.9 1627.6 9.87 Example 4 0.1 1 2 20 76.9 1627.31 11.02 Example 5 0.1 1 10 20 68.9 1627.89 10.1 Example 6 0.1 1 2 8 88.9 1626.89 8.75 Example 7 0.1 1 2 21 75.9 1626.85 12.56 Example 8 0.1 1 1 20 77.9 1626.77 14.61 Example 9 0.1 1 12 20 66.9 1626.76 9.98

[0141] It can be seen from Table 1 that when the core layer 11 in the gain fiber 10 for extending the L-band amplification bandwidth provided by the present invention is composed of the following components in molar percentage: 0.01-0.1 mol% Er2O3, 0.1-1 mol% Yb2O3, 9-20 mol% P2O5, 2-10 mol% Al2O3, and the remainder is SiO2, the 10 dB gain wavelength of the prepared test optical path structure 20 is at least greater than or equal to 1627.1 nm, and the fiber corrugation can be maintained below 11.02 dB; this indicates that the gain fiber 10 for extending the L-band amplification bandwidth provided by the present invention can extend the L-band amplification bandwidth of the traditional erbium-ytterbium co-doped fiber to 1627 nm, and has a relatively low fiber corrugation.

[0142] In summary, different from the prior art, the gain fiber 10 for extending the L-band amplification bandwidth provided by the present invention optimizes the doping process of the core layer 11, and dopes erbium, ytterbium, phosphorus and aluminum elements in the core layer 11. At the same time, by adjusting the ratio of phosphorus and aluminum elements, the L-band gain bandwidth of the gain fiber 10 is effectively extended, and a double cladding structure design is adopted, which greatly reduces the pump cost of the prepared optical fiber amplifier.

[0143] It should be noted that the above embodiments all belong to the same inventive concept, and the description of each embodiment has its own focus. For matters that are not described in detail in some embodiments, reference may be made to the description in other embodiments.

[0144] The above embodiments only express the implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A gain optical fiber for extending L-band amplification bandwidth, characterized in that: It comprises a core layer, an inner cladding layer, an outer cladding layer and a coating layer which are arranged in sequence from the inside to the outside along the radial direction, wherein the core layer is composed of the following components in molar percentage: 0.01-0.1 mol% Er2O3, 0.1-1 mol% Yb2O3, 9-20 mol% P2O5, 2-10 mol% Al2O3, and the balance is SiO2; Among them, the refractive index of the core layer is greater than the refractive index of the inner cladding, the refractive index of the inner cladding is greater than the refractive index of the outer cladding, and the refractive index of the outer cladding is greater than the refractive index of the coating layer; the material of the inner cladding is SiO2, and the material of the outer cladding is any one of polyacrylate, polyimide and fluorine-doped SiO2.

2. The gain optical fiber for extending L-band amplification bandwidth according to claim 1, characterized in that: The cross section of the inner cladding is any one of a regular octagon, a quincunx shape, a D shape and a regular hexagon.

3. A method for preparing a gain optical fiber with extended L-band amplification bandwidth as claimed in any one of claims 1 to 2, characterized in that: The method comprises: S10, depositing on the inner wall of a substrate tube to form a loose layer; S20, removing the substrate tube and soaking it until it contains Er 3+ , Yb 3+ and Al 3+ The doping solution is immersed in the doping solution, and the loose layer is dried and oxidized in sequence to form an oxidation reaction tube; S30, performing phosphorus deposition and sintering treatment on the oxidation reaction tube to form a mother rod; S40, performing a collapse and sintering process on the mother rod to form an optical fiber preform rod including the core layer; S50, performing a casing treatment on the optical fiber preform rod after testing according to a fixed core-to-cladding ratio to form a casing rod, wherein the casing rod includes the inner cladding; S60, performing drawing and coating processing on the sleeve rod respectively to obtain a gain optical fiber with an extended L-band amplification bandwidth including the coating layer.

4. The method for preparing a gain optical fiber with extended L-band amplification bandwidth according to claim 3, characterized in that: The step S10 specifically includes: The loose layer is deposited on the inner wall of the substrate tube by the MCVD process, wherein the deposition gas used in the MCVD process is SiCl4 and the deposition temperature is 1400°C.

5. The method for preparing a gain optical fiber with extended L-band amplification bandwidth according to claim 3, characterized in that: In the step S20, the drying gas used to dry the loose layer is Cl2, and the drying temperature is 900°C; the oxidizing gas used to oxidize the loose layer is O2, and the oxidizing temperature is 1300°C.

6. The method for preparing a gain optical fiber with extended L-band amplification bandwidth according to claim 3, characterized in that: In the step S30, the loose layer is subjected to phosphorus deposition and sintering treatment using POCl3 and O2, and the sintering temperature is 1400°C.

7. The method for preparing a gain optical fiber with extended L-band amplification bandwidth according to claim 3, characterized in that: In the step S40, the core layer is composed of the following components in molar percentage: 0.01-0.1 mol% Er2O3, 0.1-1 mol% Yb2O3, 9-20 mol% P2O5, 2-10 mol% Al2O3, and the remainder is SiO2.

8. The method for preparing a gain optical fiber with extended L-band amplification bandwidth according to claim 3, characterized in that: In the step S50, the cross section of the inner cladding is any one of a regular octagon, a quincunx shape, a D shape, and a regular hexagon.

Images