An S-band gain optical fiber and an optical fiber amplifier thereof

Abstract

The invention discloses an S-band gain optical fiber and an optical fiber amplifier thereof, and relates to the field of optical fiber communication technology. The S-band gain optical fiber comprises: a core, an inner cladding, an outer cladding and a coating layer; an optical fiber amplifier using the optical fiber comprises: a tunable laser signal source, a pump source, a ternary co-doped quartz optical fiber of yttrium aluminum and thulium, a wavelength division multiplexer, a circulator and a spectrum analyzer. The S-band gain optical fiber of the invention has a lower maximum phonon energy than a traditional optical fiber by doping yttrium aluminum and thulium ions of different concentrations, and can be well fused with a standard quartz optical fiber. The optical fiber amplifier using the optical fiber can effectively achieve a gain greater than 35dB within 1460nm to 1520nm, and the pump source technology used is relatively mature and has a high pumping efficiency; the noise coefficient within the wavelength range of 1460nm to 1520nm is small, and the noise coefficient at the highest gain peak is less than 6dB; and the optical-to-optical conversion efficiency of more than 50% can be achieved within the wavelength range of 1460nm to 1520nm.

Description

Technical Field

[0001] The present invention relates to the field of optical fiber communication technology, and in particular to an S-band gain optical fiber and an optical fiber amplifier thereof. Background Art

[0002] In recent years, with the vigorous development of cutting-edge technologies such as the Internet of Things, cloud computing, big data, virtual reality, and artificial intelligence, global network data traffic has shown explosive growth, which requires major infrastructure transformation of existing telecommunications networks. The new generation of technology requires not only the renewal of network infrastructure, but also the improvement of speed and capacity. How to make full use of the low-loss (<0.3dB / km) area of ​​silica optical fiber near 200nm (1450-1650nm) to meet the growing bandwidth demand has become a research hotspot. At present, mainstream communication networks mainly rely on the low-loss window of quartz optical fiber in the C-band (1530-1565nm). However, due to challenges such as amplification noise and nonlinear effects of optical signals during transmission, the transmission capacity of the C-band has gradually approached its theoretical upper limit, so people have turned their attention to the S-band close to the C-band.

[0003] At present, there are four main types of optical amplifiers acting in the S band, namely Raman fiber amplifier, semiconductor amplifier, bismuth-doped fiber amplifier and rare earth-doped fiber amplifier. Among them, Raman amplifier has the advantages of low noise coefficient and simple structure, but at the same time, it has the disadvantage that the required gain fiber length is too long, which is not conducive to the integration of optical amplification modules; semiconductor lasers can cover the low-loss window range of 1310nm and 1550nm of quartz fiber, and the preparation process is relatively mature, but it is sensitive to the polarization characteristics of light, and multiple optical amplifier integrated systems are greatly affected by nonlinear effects; bismuth-doped fiber amplifiers have the advantages of simple structure, wide bandwidth, high gain and low noise, which makes them attract much attention in the research of S-band amplifiers, but they also have the disadvantages of high requirements for pump wavelength and power and long gain fiber length; rare earth-doped fiber amplifiers have the advantages of high saturated output power and polarization independence. Different rare earth ions absorb pump light of different wavelengths and can excite lasers of specific wavelengths. At the same time, the doped rare earth ions usually have rich transition energy levels, which can be carried out through pump combinations of different wavelengths. Therefore, rare earth-doped fiber amplifiers have become a hot spot in optical amplification.

[0004] Rare earth doped amplifiers also face some challenges. First, in the high phonon energy gain medium, Tm 3 + has a higher probability of non-radiative transition, resulting in a reduced excited state lifetime and lower quantum efficiency. Common matrix materials include quartz glass, fluoride glass, silicate glass, and tellurite glass. Quartz glass has low cost and low loss, but its high phonon energy (about 1100cm -1 ) reduces Tm3+ The quantum efficiency of fluoride glass is low (about 580cm -1 ), but its thermal properties and chemical stability are poor, and it is very easy to deliquesce, which is not conducive to welding; tellurite glass has a lower phonon energy than quartz glass (about 700cm -1 ), good chemical stability, and a wide theoretical gain bandwidth, are ideal for solving the phonon energy problem. The second problem is the upper energy level in Tm3+ 3 H4 lifetime is shorter than the lower energy level 3 F4, it is difficult to achieve population inversion. In the quartz matrix, Tm 3+ The upper energy level 3 The lifetime of H4 is 14.2μs, which is shorter than that of the lower energy level. 3 F4334.7μs.

[0005] In addition, although Tm 3+ It has abundant transition energy levels, but how to use existing pump sources and various doped optical fibers to achieve high amplification gain and low noise coefficient brings challenges to S-band amplification. When evaluating the working performance of optical fiber amplifiers, threshold pump power and power conversion efficiency are two key parameters. First, the threshold pump power is the minimum pump power required for the normal operation of the amplifier. Only when the pump power reaches or exceeds this threshold can the amplifier effectively convert the pump energy into signal light power. Secondly, the power conversion efficiency measures the ability of the amplifier to convert pump power into signal light power after reaching the threshold. However, this efficiency does not increase infinitely, but has a maximum value. As the length of the optical fiber increases, its loss to the laser signal will also increase, resulting in a decrease in power conversion efficiency. On the other hand, Tm 3+ Doping concentration is one of the key factors affecting the output performance of fiber amplifiers. To enhance the signal gain of thulium-doped fiber amplifiers, an effective method is to use core fibers with high doping concentrations. This approach can significantly shorten the doped fiber length of the amplifier, reduce the loss of laser signals by the long fiber matrix, and help achieve the gain shift of thulium-doped fiber amplifiers. However, too high a doping concentration may lead to the formation of ion clusters, resulting in uneven distribution of doping concentration in the fiber, which will have a serious adverse effect on system performance. On the other hand, if the doping concentration is too low, the pump energy may not be fully absorbed. In the area where the total effective number of doped particles is lower than the incident photon, the iron ions at the ground state energy level may be depleted, resulting in the forced interruption of the signal gain process and the inability to obtain a large signal gain. Therefore, the design and optimization of fiber amplifiers need to comprehensively consider multiple factors such as threshold pump power, optical-to-optical conversion efficiency, and fiber length to achieve optimal performance.

[0006] US Patent No. 6924928B2 proposed a gallium, aluminum and thulium co-doped silica matrix optical fiber, which improved 3 The H4 energy level lifetime uses 1400 / 1550nm dual-wavelength pumping. Although gain shift is achieved in the S band, the gain in the S+ band is too small and the pumping efficiency is not high.

[0007] Chinese patent CN117050753A proposes a method for enhancing the S-band emission intensity of thulium luminescent materials by sensitizer doping. This method requires complex calculations of the energy levels of the luminescent center ion thulium ion and the sensitizer center ion, and at the same time, it is necessary to adjust the doping ratio of rare earth nanoparticles and sensitizer ions. The experimental parameters are complex and require precise calculations to obtain matching energy levels and doping ratios. It is difficult to implement and the efficiency of improving the luminescent intensity is not high.

[0008] Chinese patent CN1317600C proposes a gain-shifted thulium-doped fiber amplifier that uses a spontaneous emission light source as an auxiliary pump. The pump source uses the ASE output light of the erbium-doped fiber as an auxiliary. This design can reduce the manufacturing cost of the product, but the patent has a low gain in the S+ band and a large noise coefficient.

[0009] In summary, conventional S-band optical fibers and optical fiber amplifiers cannot well meet the requirements of high gain, low noise coefficient and high optical-to-optical conversion efficiency in the S-band. In order to solve the above problems, the present invention proposes an S-band gain optical fiber and an optical fiber amplifier thereof. Summary of the invention

[0010] The purpose of the present invention is to provide an S-band gain optical fiber and an optical fiber amplifier thereof to solve the problems raised in the background technology:

[0011] Traditional S-band optical fibers and optical fiber amplifiers cannot meet the requirements of high gain, low noise figure and high optical-to-optical conversion efficiency in the S-band.

[0012] In order to achieve the above object, the present invention adopts the following technical solutions:

[0013] An S-band gain optical fiber comprises: a fiber core, an inner cladding, an outer cladding and a coating layer, wherein the diameter of the fiber core ranges from 6 μm to 10 μm, and the inner cladding is a regular octagon; the fiber core contains ternary co-doped ions of yttrium, aluminum and thulium, and the doping concentration distribution of the doped ions in the fiber core is a gradient type.

[0014] Preferably, the doping concentration of yttrium in the fiber core is in the range of 37.26 mol% to 74.9 mol%, the doping concentration of aluminum is in the range of 8.42 mol% to 16.8 mol%, and the doping concentration of thulium is in the range of 0.8 mol% to 8.3 mol%.

[0015] Preferably, the numerical aperture of the core and the inner cladding is in the range of 0.05≤NA≤0.20.

[0016] A fiber amplifier using S-band gain fiber comprises: a tunable laser signal source, a pump source, a yttrium-aluminum-thulium ternary co-doped quartz fiber, a wavelength division multiplexer, a circulator and a spectrum analyzer. The amplifier adopts two-stage amplification; the first-stage amplification part of the amplifier adopts conventional thulium-doped quartz fiber, and the second-stage amplification part adopts yttrium-aluminum-thulium ternary co-doped fiber with a quartz matrix.

[0017] Preferably, the wavelength range of the tunable laser signal source is 1460nm-1530nm.

[0018] Preferably, the pump source comprises a single-mode pump source with a central wavelength of 1400 nm and a single-mode pump source with a central wavelength of 1570 nm.

[0019] Preferably, the wavelength division multiplexer has three single-mode wavelength division multiplexers, the first single-mode wavelength division multiplexer multiplexes the signal source 1460nm band and the pump source 1570nm band, and the second and third single-mode wavelength division multiplexers multiplex the signal source 1460nm band and the pump source 1400nm band.

[0020] Compared with the prior art, the present invention provides an S-band gain optical fiber and an optical fiber amplifier thereof, which have the following beneficial effects:

[0021] The S-band gain optical fiber of the present invention has a lower maximum phonon energy than the traditional optical fiber by doping different concentrations of yttrium aluminum thulium ions, which solves the problem of Tm in the gain medium with high phonon energy. 3+ The probability of non-radiative transition is high, resulting in a decrease in excited state lifetime and a decrease in quantum efficiency; and the S-band gain fiber of the present invention can be well fused with the standard quartz fiber, overcoming the problems of easy deliquesce and difficult fusion of traditional fluoride fibers, and reducing additional fusion loss; the optical fiber amplifier using the S-band gain fiber of the present invention can effectively achieve a gain greater than 35dB within the range of 1460nm to 1520nm, the pump source technology used is relatively mature, and has a high pump efficiency; the noise coefficient within the wavelength range of 1460nm to 1520nm is small, and the noise coefficient at the highest gain peak is less than 6dB; within the wavelength range of 1460nm to 1520nm, a light-to-light conversion efficiency of more than 50% can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic cross-sectional view of an S-band gain optical fiber mentioned in an embodiment of the present invention;

[0023] Figure 2A graph showing the relationship between the doping concentration and doping radius of each component of the S-band gain optical fiber mentioned in an embodiment of the present invention;

[0024] Figure 3 A schematic diagram showing the comparison of Raman spectra of an S-band gain optical fiber and a pure thulium-doped silica optical fiber mentioned in an embodiment of the present invention;

[0025] Figure 4 This is a diagram of an optical fiber amplifier experimental device using an S-band gain optical fiber mentioned in an embodiment of the present invention;

[0026] Figure 5 This is a graph showing the optical-to-optical conversion efficiency of an optical fiber amplifier experimental device using an S-band gain optical fiber as a function of the total transmission power mentioned in an embodiment of the present invention;

[0027] Figure 6 The gain and noise coefficient of the optical fiber amplifier using S-band gain optical fiber mentioned in the embodiment of the present invention are graphs as a function of wavelength. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0029] The S-band gain optical fiber of the present invention has a lower maximum phonon energy than the traditional optical fiber by doping different concentrations of yttrium aluminum thulium ions, which solves the problem of Tm in the gain medium with high phonon energy. 3+ The probability of non-radiative transition is high, resulting in reduced excited state lifetime and reduced quantum efficiency; and the S-band gain fiber of the present invention can be well fused with standard quartz fiber, overcoming the problems of easy deliquesce and difficult fusion of traditional fluoride fiber, and reducing additional fusion loss; the fiber amplifier using the S-band gain fiber of the present invention can effectively achieve a gain greater than 35dB within 1460nm to 1520nm, and the pump source technology used is relatively mature and has a high pump efficiency; the noise coefficient within the wavelength range of 1460nm to 1520nm is small, and the noise coefficient at the highest gain peak is less than 6dB; within the wavelength range of 1460nm to 1520nm, a light-to-light conversion efficiency of more than 50% can be achieved. Specifically include the following contents.

[0030] Reference Figure 1 The present invention provides an S-band gain optical fiber, comprising: a core, an inner cladding, an outer cladding and a coating layer, wherein the diameter of the core is in the range of 6 μm to 10 μm, and the inner cladding is a regular octagon; the core contains ternary co-doped ions of yttrium aluminum and thulium, and the doping concentration distribution of the doped ions in the core is a gradient type. The relationship between the doping concentration of different components in the core and the doping radius can be referred to Figure 2As can be seen from the figure, the optimal doping concentration range of yttrium in the core is 37.26mol%~74.9mol%, the optimal doping concentration range of aluminum is 8.42mol%~16.8mol%, and the optimal doping concentration range of thulium is 0.8mol%~8.3mol%. The numerical aperture range of the core and the inner cladding is 0.05≤NA≤0.20.

[0031] The Raman spectra of pure thulium-doped silica fiber and co-doped fiber doped with yttrium aluminum and thulium are compared. The specific results can be found in Figure 3 As can be seen from the figure, when the Raman intensity peak of the co-doped optical fiber doped with yttrium aluminum thulium remains unchanged, the phonon energy is lower, which can effectively reduce the impact of high non-radiative transition probability and low power conversion efficiency caused by excessive phonon energy.

[0032] Reference Figure 4 , a fiber amplifier using S-band gain fiber, comprising: a tunable laser signal source, a pump source, a yttrium aluminum thulium ternary co-doped silica fiber, a wavelength division multiplexer, a circulator and a spectrum analyzer, wherein the amplifier adopts two-stage amplification; the first-stage amplification part of the amplifier adopts conventional thulium-doped silica fiber, and the second-stage amplification part adopts yttrium aluminum thulium ternary co-doped fiber with a quartz matrix. The wavelength range of the tunable laser signal source is 1460nm to 1530nm. The pump source includes a single-mode pump source with a central wavelength of 1400nm and a single-mode pump source with a central wavelength of 1570nm. The wavelength division multiplexer has three single-mode wavelength division multiplexers, the first single-mode wavelength division multiplexer multiplexes the signal source 1460nm band and the pump source 1570nm band, and the second and third single-mode wavelength division multiplexers multiplex the signal source 1460nm band and the pump source 1400nm band.

[0033] Based on the above-mentioned S-band gain fiber amplifier, the optical-to-optical conversion efficiency is tested under different input signal wavelengths (from 1470 to 1520nm), and a change graph of the optical-to-optical conversion efficiency is drawn based on the average test results. The specific results can be referred to Figure 5 ,It can be seen from the figure that as the wavelength of the input signal increases, the ,optical conversion efficiency of the amplifier gradually increases with the increase of the total ,pump power, and the highest power conversion efficiency exceeds 50%.

[0034] Reference Figure 6 The amplifier can achieve a maximum gain of more than 35dB in the wavelength range of 1460nm to 1520nm, and the noise coefficient of the optical fiber amplifier in the wavelength range of 1460nm to 1520nm is small, and the noise coefficient at the highest gain peak is also less than 6dB.

[0035] Embodiment 1:

[0036] An S-band gain optical fiber, the silica matrix doped optical fiber consists of a core layer and two cladding layers. The fiber core contains ternary co-doped ions of yttrium, aluminum and thulium, and the doping concentration distribution of the doped ions in the fiber core is a gradient type. The doping concentration of thulium is 0.8 mol%, the doping concentration of yttrium is 37.26 mol%, and the doping concentration of aluminum is 8.42 mol%.

[0037] A fiber amplifier using S-band gain fiber, the amplifier consists of two pump sources, three single-mode wavelength division multiplexers, rare earth doped fiber, a circulator and a spectrum analyzer: the first pump source is a single-mode pump with a central wavelength of 1570nm, which serves as the forward pump of the amplifier; the second and third pump sources are single-mode pumps with a central wavelength of 1400nm, which serve as the reverse pump of the amplifier; the doped fiber used for the first-stage amplification is a conventional thulium-doped quartz fiber, and the fiber used for the second-stage amplification is a ternary co-doped fiber of yttrium aluminum and thulium, with a maximum phonon energy of 830cm -1 The output power of the first pump is set to 450mW. The output power of the second pump is set to 300mW. The gain of the fiber amplifier reaches a maximum value of 27.5dB at 1485nm, the optical-to-optical conversion efficiency is 40.6%, and the noise figure is 4.7dB.

[0038] Embodiment 2:

[0039] The invention discloses an S-band gain optical fiber, which is a quartz matrix doped optical fiber consisting of a core layer and two cladding layers. The fiber core contains ternary co-doped ions of yttrium, aluminum and thulium, and the doping concentration distribution of the doped ions in the fiber core is a gradient type.

[0040] A fiber amplifier using S-band gain fiber, the amplifier consists of two pump sources, three single-mode wavelength division multiplexers, rare earth doped fiber, a circulator and a spectrum analyzer: the first pump source is a single-mode pump with a central wavelength of 1570nm, which serves as the forward pump of the amplifier; the second and third pump sources are single-mode pumps with a central wavelength of 1400nm, which serve as the reverse pump of the amplifier; the doped fiber used for the first-stage amplification is a conventional thulium-doped quartz fiber, and the fiber used for the second-stage amplification is a ternary co-doped fiber of yttrium aluminum and thulium, with a maximum phonon energy of 830cm -1 , the doping concentration of thulium is 1.45mol%, the doping concentration of yttrium is 42.53mol%, and the doping concentration of aluminum is 9.13mol%. The output power of the first pump is set to 450mW. The output power of the second pump is set to 350mW. The gain of the fiber amplifier reaches a maximum value of 29.5dB at 1492nm, the optical-to-optical conversion efficiency is 41.5%, and the noise figure is 4.9dB.

[0041] Embodiment 3:

[0042] An S-band gain optical fiber, the silica matrix doped optical fiber consists of a core layer and two cladding layers. The fiber core contains ternary co-doped ions of yttrium, aluminum and thulium, and the doping concentration distribution of the doped ions in the fiber core is a gradient type. The doping concentration of thulium is 2.3 mol%, the doping concentration of yttrium is 50.17 mol%, and the doping concentration of aluminum is 9.85 mol%.

[0043] A fiber amplifier using S-band gain fiber, the amplifier consists of two pump sources, three single-mode wavelength division multiplexers, rare earth doped fiber, a circulator and a spectrum analyzer: the first pump source is a single-mode pump with a central wavelength of 1570nm, which serves as the forward pump of the amplifier; the second and third pump sources are single-mode pumps with a central wavelength of 1400nm, which serve as the reverse pump of the amplifier; the doped fiber used for the first-stage amplification is a conventional thulium-doped quartz fiber, and the fiber used for the second-stage amplification is a ternary co-doped fiber of yttrium aluminum and thulium, with a maximum phonon energy of 830cm -1 The first pump output power is set to 450mW. The second pump output power is set to 400mW. The gain of the fiber amplifier reaches a maximum value of 30.4dB at 1498nm, the power conversion efficiency is 43.8%, and the noise figure is 5.3dB.

[0044] Embodiment 4:

[0045] An S-band gain optical fiber, the silica matrix doped optical fiber consists of a core layer and two cladding layers. The fiber core contains ternary co-doped ions of yttrium, aluminum and thulium, and the doping concentration distribution of the doped ions in the fiber core is a gradient type. The doping concentration of thulium is 3.5mol%, the doping concentration of yttrium is 62.48mol%, and the doping concentration of aluminum is 10.16mol%.

[0046] A fiber amplifier using S-band gain fiber, the amplifier consists of two pump sources, three single-mode wavelength division multiplexers, rare earth doped fiber, a circulator and a spectrum analyzer: the first pump source is a single-mode pump with a central wavelength of 1570nm, which serves as the forward pump of the amplifier; the second and third pump sources are single-mode pumps with a central wavelength of 1400nm, which serve as the reverse pump of the amplifier; the doped fiber used for the first-stage amplification is a conventional thulium-doped quartz fiber, and the fiber used for the second-stage amplification is a ternary co-doped fiber of yttrium aluminum and thulium, with a maximum phonon energy of 830cm -1 The first pump output power is set to 450mW. The second pump output power is set to 450mW. The gain of the fiber amplifier reaches a maximum value of 32.4dB at 1503nm, the optical-to-optical conversion efficiency is 45.7%, and the noise figure is 5.3dB.

[0047] Embodiment 5:

[0048] An S-band gain optical fiber, the silica matrix doped optical fiber consists of a core layer and two cladding layers. The fiber core contains ternary co-doped ions of yttrium, aluminum and thulium, and the doping concentration distribution of the doped ions in the fiber core is a gradient type. The doping concentration of thulium is 4.2mol%, the doping concentration of yttrium is 67.32mol%, and the doping concentration of aluminum is 16.8mol%.

[0049] A fiber amplifier using S-band gain fiber, the amplifier consists of two pump sources, three single-mode wavelength division multiplexers, rare earth doped fiber, a circulator and a spectrum analyzer: the first pump source is a single-mode pump with a central wavelength of 1570nm, which serves as the forward pump of the amplifier; the second and third pump sources are single-mode pumps with a central wavelength of 1400nm, which serve as the reverse pump of the amplifier; the doped fiber used for the first-stage amplification is a conventional thulium-doped quartz fiber, and the fiber used for the second-stage amplification is a ternary co-doped fiber of yttrium aluminum and thulium, with a maximum phonon energy of 830cm -1 The output power of the first pump is set to 450mW. The output power of the second pump is set to 500mW. The gain of the fiber amplifier reaches a maximum value of 30.4dB at 1513nm, the optical-to-optical conversion efficiency is 48.2%, and the noise figure is 5.3dB.

[0050] Embodiment 6:

[0051] An S-band gain optical fiber, the silica matrix doped optical fiber consists of a core layer and two cladding layers. The fiber core contains ternary co-doped ions of yttrium, aluminum and thulium, and the doping concentration distribution of the doped ions in the fiber core is a gradient type. The doping concentration of thulium is 8.3mol%, the doping concentration of yttrium is 74.9mol%, and the doping concentration of aluminum is 11.6mol%.

[0052] A fiber amplifier using S-band gain fiber, the amplifier consists of two pump sources, three single-mode wavelength division multiplexers, rare earth doped fiber, a circulator and a spectrum analyzer: the first pump source is a single-mode pump with a central wavelength of 1570nm, which serves as the forward pump of the amplifier; the second and third pump sources are single-mode pumps with a central wavelength of 1400nm, which serve as the reverse pump of the amplifier; the doped fiber used for the first-stage amplification is a conventional thulium-doped quartz fiber, and the fiber used for the second-stage amplification is a ternary co-doped fiber of yttrium aluminum and thulium, with a maximum phonon energy of 830cm -1 The first pump output power is set to 450mW. The second pump output power is set to 550mW. The gain of the fiber amplifier reaches a maximum value of 30.4dB at 1513nm, the optical-to-optical conversion efficiency is 50.2%, and the noise figure is 5.3dB.

[0053] Based on the parameters of Examples 1-6, the fiber amplifiers of S-band gain fibers with different Yttrium aluminum thulium doping concentrations in the corresponding embodiments are applied, and the main performances of the S-band gain fibers and their corresponding amplifiers are tested and summarized. The specific results can be referred to Table 1-2:

[0054] Table 1 Power conversion efficiency of the fiber amplifier of the implementation example

[0055] project Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Pump power(mW) 1050 1150 1250 1350 1450 1550 Light to light conversion efficiency (%) 42.3 44.5 46.8 48.1 49.3 50.2 Thulium concentration (mol%) 0.8 1.45 2.3 3.5 4.2 8.3 Yttrium concentration (mol%) 37.26 42.53 50.17 62.48 67.32 74.9 Aluminum concentration (mol%) 8.42 9.13 9.85 10.16 16.8 11.6

[0056] Table 2 Gain and noise figure of the fiber amplifier of the implementation example

[0057] Wavelength (nm) 1470 1475 1480 1485 1490 1495 1500 1505 1510 1515 1520 Gain(dB) 28.5 30.3 32.1 33.9 35.6 33.6 31.2 30.1 28.2 26.3 24.7 Noise Figure(dB) 6.5 6.35 6.2 6.05 5.91 6.11 6.19 6.31 6.41 6.55 6.7

[0058] It can be seen from the table that the optical-to-optical conversion efficiency of the optical fiber amplifiers prepared in Examples 1-6 increases with the increase of the pump power, and the optical-to-optical conversion efficiency is higher than 40%, and the highest can reach more than 50%. The gain is higher than 24dB, and the highest gain reaches 35.6dB, and the noise coefficient at the highest peak also reaches the lowest 5.91dB accordingly.

[0059] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. An S-band gain optical fiber, characterized in that: include: A fiber core, an inner cladding, an outer cladding and a coating layer, wherein the diameter of the fiber core ranges from 6 μm to 10 μm, and the inner cladding is a regular octagon; The fiber core contains ternary co-doped ions of yttrium, aluminum and thulium, and the doping concentration distribution of the doped ions in the fiber core is a gradient type; The doping concentration of yttrium in the fiber core is in the range of 37.26mol% to 74.9mol%, the doping concentration of aluminum is in the range of 8.42mol% to 16.8mol%, and the doping concentration of thulium is in the range of 0.8mol% to 8.3mol%; The numerical aperture range of the core and the inner cladding is 0.05≤NA≤0.

20.

2. An optical fiber amplifier using the optical fiber as claimed in claim 1, characterized in that: include: A tunable laser signal source, a pump source, a yttrium-aluminum-thulium ternary co-doped quartz optical fiber, a wavelength division multiplexer, a circulator and a spectrum analyzer are provided. The amplifier adopts two-stage amplification; the first-stage amplification part of the amplifier adopts conventional thulium-doped quartz optical fiber, and the second-stage amplification part adopts yttrium-aluminum-thulium ternary co-doped optical fiber with a quartz matrix.

3. The optical fiber amplifier using S-band gain optical fiber according to claim 2, characterized in that: The wavelength range of the tunable laser signal source is 1460nm~1530nm.

4. The optical fiber amplifier using S-band gain optical fiber according to claim 3, characterized in that: The pump source includes a single-mode pump source with a central wavelength of 1400 nm and a single-mode pump source with a central wavelength of 1570 nm.

5. The optical fiber amplifier using S-band gain optical fiber according to claim 4, characterized in that: The wavelength division multiplexer has three single-mode wavelength division multiplexers. The first single-mode wavelength division multiplexer multiplexes the signal source 1460nm band and the pump source 1570nm band. The second and third single-mode wavelength division multiplexers multiplex the signal source 1460nm band and the pump source 1400nm band.

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