Fiber optics and optical transmission systems

Abstract

This disclosure provides an optical fiber and an optical transmission system, belonging to the field of optical communication technology. The optical fiber includes a core layer and a cladding layer. The core layer comprises at least two layers distributed from the inside out. The cladding layer surrounds the core layer and includes a first recessed layer and an inner cladding layer distributed from the inside out. The refractive index of each layer in the core layer increases sequentially from the inside out. The refractive index of the outermost layer of the core layer is greater than the refractive index of any layer in the cladding layer, and the refractive index of the first recessed layer is less than the refractive index of the inner cladding layer. This optical fiber has a relatively large effective area, a low cutoff wavelength, and maintains good bending performance.

Description

Technical Field

[0001] This disclosure relates to the field of optical communication technology, and in particular to an optical fiber and an optical transmission system. Background Technology

[0002] Against the backdrop of the demand for high-speed interconnection in data centers and the rapid development of network technology, broadband high-speed communication will become the mainstream application in the future. However, with the increase in speed, the nonlinear effect of optical fiber has a more and more serious impact on transmission performance. For example, in wavelength division multiplexing technology, the nonlinear effect of optical fiber will lead to signal distortion and increased noise, which limits the transmission distance and capacity.

[0003] The nonlinear effects of optical fibers are positively correlated with optical power density; for example, the higher the optical power density, the more severe the nonlinear effects. Therefore, the nonlinear effects can be mitigated by reducing the optical power density. For instance, increasing the effective area of ​​the optical fiber can reduce the optical power density and further reduce the nonlinear effects. However, increasing the effective area of ​​the optical fiber often leads to an increase in the cutoff wavelength and macrobending loss.

[0004] Therefore, how to make optical fibers have a large effective area while having relatively small cutoff wavelength and macrobending loss is a research direction that those skilled in the art are dedicated to studying. Summary of the Invention

[0005] This disclosure provides an optical fiber and an optical transmission system, wherein the optical fiber has a relatively large effective area, a low cutoff wavelength, and maintains good bending performance.

[0006] In a first aspect, this disclosure provides an optical fiber, the optical fiber comprising a core layer and a cladding layer, the core layer comprising at least two layers distributed from the inside to the outside, and the cladding layer wrapping around the core layer, comprising a first recessed layer and an inner cladding layer distributed from the inside to the outside;

[0007] The refractive index of each layer of the core layer increases sequentially from the inside to the outside. The refractive index of the outermost layer of the core layer is greater than the refractive index of any layer in the cladding. The refractive index of the first sunken layer is less than the refractive index of the inner cladding.

[0008] In the scheme disclosed herein, the refractive index of each layer in the fiber core increases sequentially from the inside out. Through simulation and experimental design, the refractive index and radius of each layer are determined, enabling the optical fiber to possess a large effective area and a low cutoff wavelength. The refractive index of the first depressed layer is lower than that of the inner cladding layer, and the refractive index of the inner cladding layer is lower than that of the outermost layer of the fiber core. This significant difference in refractive index between the first depressed layer and the outermost layer of the fiber core allows for low macrobending loss in the optical fiber through simulation and experimental design. Therefore, this optical fiber possesses a large effective area, a low cutoff wavelength, and good bending performance.

[0009] For example, this optical fiber can achieve an effective area greater than 150 μm corresponding to a beam with a transmission wavelength of 1550 nm. 2 A beam with a cutoff wavelength of less than 1500nm and a transmission wavelength of 1625nm exhibits a bending loss of less than 0.10dB under the condition of a bending radius of 30mm and 100 bends.

[0010] In one possible implementation, the material of the outermost layer of the fiber core layer and the material of the first recessed layer both include silica quartz glass and doping elements, the refractive index of the outermost layer of the fiber core layer is greater than the refractive index of the silica quartz glass, and the refractive index of the first recessed layer is less than the refractive index of the silica quartz glass.

[0011] In the scheme disclosed herein, the refractive index of the outermost layer of the fiber core is greater than that of the silica quartz glass, while the refractive index of the first recessed layer surrounding the outermost layer of the fiber core is less than that of the silica quartz glass. This widens the gap between the refractive index of the outermost layer of the fiber core and the refractive index of the first recessed layer, thereby further reducing macrobending loss and improving the bending performance of the optical fiber.

[0012] In one possible implementation, the relative refractive index difference Δn3 of the first recessed layer relative to the silica quartz glass ranges from -0.30 ≤ Δn3 ≤ -0.021%, and the annular width W2 of the first recessed layer ranges from 0.30 μm ≤ W2 ≤ 4.50 μm.

[0013] In the scheme disclosed herein, through simulation and experimental testing, the relative refractive index difference Δn3 of the first recessed layer relative to the silica quartz glass ranges from -0.30 ≤ Δn3 ≤ -0.021%, and the ring width W2 of the first recessed layer ranges from 0.30 μm ≤ W2 ≤ 4.50 μm. This enables the optical fiber to transmit an optical signal with a wavelength of 1625 nm, a bending radius of 30 mm, and bend 100 times, with a corresponding macro-bending loss of 0.069 dB, which is far lower than 0.10 dB, thus exhibiting good bending performance.

[0014] In one possible implementation, the fiber core layer includes an inner core layer and an outer core layer, both of which are made of silica quartz glass and doped elements.

[0015] The relative refractive index difference Δn1 between the inner core layer and the silica quartz glass ranges from -0.021% to 0.24%, and the relative refractive index difference Δn2 between the outer core layer and the silica quartz glass ranges from 0.16% to 0.39%.

[0016] In one possible implementation, the radius R1 of the inner core layer is in the range of 0.90um≤R1≤6.0um, and the ring width W1 of the outer core layer is in the range of 1.10um≤W1≤6.00um.

[0017] In the scheme disclosed herein, through simulation and experimentation, the relative refractive index difference Δn1 of the inner core layer relative to silicon dioxide ranges from -0.021% to 0.24%, the radius R1 of the inner core layer ranges from 0.90 μm to 6.0 μm, the relative refractive index difference Δn2 of the outer core layer relative to silicon dioxide ranges from 0.16% to 0.39%, and the ring width W1 of the outer core layer ranges from 1.10 μm to 6.00 μm. This facilitates the achievement of a larger effective area and a lower cutoff wavelength in the optical fiber. For example, it enables the optical fiber to achieve an effective area of ​​150 μm for a beam with a transmission wavelength of 1550 nm. 2 Nearby, such as greater than or equal to 150um 2 The cutoff wavelength of optical fiber is below 1550nm. The lower the cutoff wavelength of optical fiber, the wider the band it can cover, and the greater its communication capacity.

[0018] In one possible implementation, the inner cladding layer is made of silica quartz glass and doping elements, the relative refractive index difference Δn4 of the inner cladding layer relative to the silica quartz glass is in the range of -0.20% ≤ Δn4 ≤ 0.20%, and the ring width W3 of the inner cladding layer is in the range of 0.70 μm ≤ W3 ≤ 6.00 μm.

[0019] In one possible implementation, the cladding further includes a second recessed layer that surrounds the inner cladding, the refractive index of the second recessed layer being less than that of the inner cladding.

[0020] In the scheme disclosed herein, a second depressed layer with a lower refractive index is arranged outside the inner cladding, which is beneficial to further reduce macrobending loss, improve the bending performance of the optical fiber, and also plays a role in further adjusting the cutoff wavelength.

[0021] In one possible implementation, the material of the second recessed layer includes silica quartz glass and doping elements, the relative refractive index difference Δn5 of the second recessed layer relative to the silica quartz glass is in the range of -0.55≤Δn5≤-0.13%, and the ring width W4 of the second recessed layer is in the range of 0.80um≤W4≤8.40μm.

[0022] In the scheme disclosed herein, by setting the refractive index and radius of the first recessed layer, the inner cladding layer and the second recessed layer, the cutoff wavelength can be further reduced and the bending performance can be improved.

[0023] In one possible implementation, the doping element in the material with a refractive index greater than that of the silica quartz glass is germanium, and the doping element in the material with a refractive index less than that of the silica quartz glass is at least one of boron and fluorine.

[0024] In one possible implementation, the cladding layer further includes an outer cladding layer, which is the outermost layer of the cladding layer, and the outer cladding layer is made of silica quartz glass.

[0025] In a second aspect, an optical transmission system is provided, the optical transmission system comprising a transmitter, a receiver and an optical fiber as described in the first aspect or any one of the first aspects, wherein the transmitter and the receiver are connected by multiple optical fiber segments. Attached Figure Description

[0026] Figure 1 This is a schematic cross-sectional view of an optical fiber provided in an exemplary embodiment of this disclosure;

[0027] Figure 2 This is a schematic diagram of the relative refractive index difference of each layer of an optical fiber relative to silica quartz glass provided in an exemplary embodiment of this disclosure;

[0028] Figure 3 This is a schematic diagram of the relative refractive index difference of the layers of an optical fiber relative to silica quartz glass provided in another exemplary embodiment of this disclosure;

[0029] Figure 4 This is a schematic diagram showing the relative refractive index difference of the layers of an optical fiber relative to silica quartz glass, provided in another exemplary embodiment of this disclosure.

[0030] Explanation of reference numerals in the attached figures

[0031] 1. Core layer; 11. Inner core layer; 12. Outer core layer.

[0032] 2. Cladding; 21. First depression layer; 22. Inner cladding; 23. Second depression layer; 24. Outer cladding. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this disclosure clearer, the embodiments of this disclosure will be described in further detail below with reference to the accompanying drawings.

[0034] This embodiment relates to an optical fiber, specifically a single-mode fiber. A single-mode fiber is an optical fiber that has only one transmission mode, which is generally the fundamental mode. Single-mode fibers are suitable for long-distance, high-capacity optical communication systems due to their low transmission loss and low transmission dispersion.

[0035] In long-distance, high-capacity optical communication systems, wavelength division multiplexing (WDM) technology is generally used for fiber optic transmission. At the transmitting end, a wavelength division multiplexer (such as a multiplexer) is used to combine optical signals of different wavelengths and send them into a single optical fiber for transmission. At the receiving end, another wavelength division multiplexer (such as a demultiplexer) separates these optical signals of different wavelengths for reception and processing. Each channel in the optical fiber is called a wavelength channel or wavelength path.

[0036] With the increasing demand for high-speed interconnection in data centers and the rapid development of network technology, the transmission rate of optical fibers needs to be improved. However, as the transmission rate further increases, the impact of the nonlinear effects of optical fibers on wavelength division multiplexing (WDM) systems becomes increasingly severe. For example, in WDM systems, the nonlinear effects of optical fibers can lead to signal distortion and increased noise. It is evident that the nonlinear effects of optical fibers in WDM systems limit transmission distance and capacity.

[0037] Among them, the nonlinear effect of optical fiber is positively correlated with optical power density (i.e., optical power per unit area). That is, the higher the optical power density, the more obvious the nonlinear effect of optical fiber.

[0038] Therefore, in high-capacity, high-speed, and long-distance optical fiber communication, the optical power density can be reduced by increasing the effective mode field area of ​​the optical fiber (i.e., the effective area, which refers to the area in the fiber core where the optical signal can be transmitted stably), thereby weakening the nonlinear effect of the optical fiber and improving the optical communication capacity and distance. Therefore, G.654 optical fiber, which has both large effective area and low attenuation coefficient characteristics, is the preferred single-mode optical fiber for future ultra-high transmission communication systems.

[0039] However, in long-distance scenarios using "C+L800G80 waves," even with a spectral efficiency (SE) of 5.3, the transmission distance using G.652D and G.654E fibers is limited. For example, without considering Raman amplification, transmission distances of 1200km and 1600km cannot be achieved. Here, "C" represents the C-band, the most commonly used band in optical communication, with a wavelength range of 1530nm to 1565nm; "L" represents the L-band, a long-wavelength band with a wavelength range of 1565nm to 1625nm; "800G" indicates a single-wavelength transmission rate of 800 gigabits (Gbps); and "80 waves" indicates the use of 80 different wavelengths of optical signals.

[0040] Therefore, in order to further improve the transmission performance of "C+L800G80 wave", the effective area of ​​the optical fiber can be continuously increased. However, the increase in the effective mode field area of ​​the optical fiber will lead to an increase in the cutoff wavelength and macrobending loss.

[0041] Among them, the cutoff wavelength is the shortest wavelength in an optical fiber that can only transmit the fundamental mode, and macrobending loss is the optical signal loss generated in the optical fiber at a large curvature radius. For example, when light is transmitted in a bent optical fiber, due to the change in the speed and direction of light propagation in the medium, some light rays will scatter and escape at the bend, thereby causing optical signal loss.

[0042] Therefore, a new type of optical fiber needs to be designed that can both meet the need for increased effective area and control the cutoff wavelength and bending loss within the required range.

[0043] This embodiment provides an optical fiber with a relatively large effective area, a low cutoff wavelength, and good bending performance. For example, the effective area corresponding to a beam with a transmission wavelength of 1550 nm is greater than 150 μm. 2 The optical fiber has a cutoff wavelength of less than 1500nm. When transmitting a beam with a wavelength of 1625nm, and under the condition of a bending radius of 30mm and 100 bends, its bending loss is less than 0.10dB, demonstrating excellent bending performance. The smaller the cutoff wavelength of the optical fiber, the wider the wavelength range of the optical signal it can transmit, and thus the greater its capacity.

[0044] The features of the optical fiber provided in this embodiment will be described below.

[0045] like Figure 1 The image shown is a schematic diagram of the cross-section of an optical fiber. (Reference) Figure 1 As shown, an optical fiber comprises a core layer 1 and a cladding layer 2. The core layer 1, also known as the fiber core, is the core component of the fiber, carrying and transmitting optical signals. The cladding layer 2 tightly wraps around the core layer 1. The refractive index of the core layer 1 is higher than that of the cladding layer 2 to ensure that light incident on the core layer 1 undergoes total internal reflection at the interface between the core layer 1 and the cladding layer 2, preventing leakage to the outside. It should be noted that the optical fiber also includes a coating layer (not shown in the figure). This coating layer wraps around the cladding layer and primarily serves to protect and enhance the flexibility of the optical fiber.

[0046] refer to Figure 1 As shown, the fiber core layer 1 comprises at least two layers, which are distributed from the inside to the outside, and the refractive index of the at least two layers of the fiber core layer 1 increases sequentially from the inside to the outside. For example, the refractive index of the outermost layer of the fiber core layer 1 is greater than that of the silica quartz glass, and the refractive index of the inner layer of the fiber core layer 1 located within the outermost layer can be greater than or less than that of the silica quartz glass.

[0047] In one example, the refractive index of each layer of the core layer 1 can be determined by doping other elements onto the silica quartz glass. In this case, the material of each layer of the core layer 1 is silica-doped quartz glass.

[0048] In this embodiment, the doped silica quartz glass is essentially silica quartz glass doped with other elements. It can also be understood that the doped silica quartz glass material includes silica quartz glass (the main material) and dopant elements (auxiliary materials). The specific dopant element(s) depends primarily on the desired refractive index. For example, if a refractive index greater than that of silica quartz glass is desired, germanium can be used as the dopant element; if a refractive index less than that of silica quartz glass is desired, at least one of boron and fluorine can be used.

[0049] For example, if the refractive index of the outermost layer of the core layer 1 is greater than that of silica quartz glass, then the material of the outermost layer of the core layer 1 can be germanium-doped silica quartz glass, so that the refractive index of the outermost layer is greater than that of silica quartz glass.

[0050] As described above, the refractive index of the inner layer of the core layer 1, located within the outermost layer, can be greater than or less than the refractive index of the silica quartz glass. If the refractive index of the inner layer of the core layer 1 is greater than that of the silica quartz glass, then the material of this layer can be germanium-doped silica quartz glass. If the refractive index of the inner layer of the core layer 1 is less than that of the silica quartz glass, then the material of this layer can be boron-doped silica quartz glass, fluorine-doped silica quartz glass, or silica quartz glass co-doped with fluorine and boron.

[0051] The refractive index of the inner layer of fiber core 1 is lower than that of the outer layer. This means that the inner layer of fiber core 1 has a weaker ability to confine light than the outer layer, causing light to diffuse towards the outer layer and thus increasing the effective mode field diameter of fiber core 1. Since the effective area is proportional to the effective mode field diameter, the lower refractive index of the inner layer of fiber core 1 compared to the outer layer increases the effective area of ​​the optical fiber.

[0052] Since the cutoff wavelength of an optical fiber is proportional to the effective mode field diameter, it is necessary to balance the effective area and the cutoff wavelength when arranging the refractive index and radius of each layer in the fiber core layer 1.

[0053] As an example, see reference Figure 1As shown, the fiber core layer 1 comprises two layers, denoted as inner core layer 11 and outer core layer 12. The refractive index of inner core layer 11 is lower than that of outer core layer 12. The radii and refractive indices of inner core layer 11 and outer core layer 12 can be determined through simulation and experimentation. For example, both inner core layer 11 and outer core layer 12 are made of doped silica quartz glass. To obtain a larger effective area and a lower dielectric wavelength, such as to satisfy the requirement of an effective area greater than 150 μm at a wavelength of 1550 nm... 2 With a cutoff wavelength less than 1500nm, simulation and experimental testing show that the relative refractive index difference Δn1 between the inner core layer 11 and the silica quartz glass can range from -0.021% to Δn1 to 0.24%, and the relative refractive index difference Δn2 between the outer core layer 12 and the silica quartz glass can range from 0.16% to Δn2 to 0.39%. The radius R1 of the inner core layer 11 can range from 0.90µm to 6.0µm, and the ring width W1 of the outer core layer 12 (reference) Figure 1 As shown, the value range of W1 (the difference between the radius R2 of the outer core layer 12 and the radius R1 of the inner core layer 11) is 1.10um≤W1≤6.00um.

[0054] It should be noted that the relative refractive index difference Δn between medium a and medium b is based on the formula... Confirmed, n in the formula a n represents the refractive index of medium a. b Let represent the refractive index of medium b. Based on the above formula, the relative refractive index difference between the inner core layer 11 and the silica quartz glass, and the relative refractive index difference between the outer core layer 12 and the silica quartz glass, can be determined.

[0055] In one example, the refractive index of the core layer 1 is generally greater than that of the silica quartz glass. Therefore, the relative refractive index difference Δn1 between the core layer 11 and the silica quartz glass can be in the range of 0 < Δn1 ≤ 0.24%.

[0056] Continue to refer to Figure 2 As shown, the cladding 2 also includes multiple layers, which are, from the inside out, a first recessed layer 21, an inner cladding 22, a second recessed layer 23 and an outer cladding 24. The refractive indices of the first recessed layer 21 and the second recessed layer 23 are both less than the refractive index of the inner cladding 22.

[0057] In one example, the first recessed layer 21, the inner cladding layer 22, and the second recessed layer 23 are all made of doped silica quartz glass. Because the refractive indices of both the first recessed layer 21 and the second recessed layer 23 are less than those of pure silica quartz glass, they are called recessed layers. The refractive index of the inner cladding layer 22 can be greater than, less than, or equal to that of the silica quartz glass.

[0058] Since the refractive index of the outermost layer of the core layer 1 is greater than that of silica quartz glass, while the refractive index of the first recessed layer 21 tightly wrapped around the outermost layer of the core layer 1 is less than that of silica quartz glass, the refractive indices of the core layer 1 and the cladding layer 2 differ significantly at the interface. This design is beneficial for reducing macrobending loss.

[0059] For example, through simulation and experimentation, the relative refractive index difference Δn3 of the first recessed layer 21 relative to the silica quartz glass ranges from -0.30 ≤ Δn3 ≤ -0.021%, and the annular width W2 of the first recessed layer 21 ranges from 0.30 μm ≤ W2 ≤ 4.50 μm. The annular width W2 of the first recessed layer 21 is referenced... Figure 1 This is the difference between the radius R3 of the first sunken layer 21 and the radius R2 of the outer core layer 12 of the fiber core layer 1.

[0060] As mentioned above, the refractive index of the inner cladding layer 22 can be greater than or less than that of the silica quartz glass. Therefore, through simulation and experimentation, the relative refractive index difference Δn4 between the inner cladding layer 22 and the silica quartz glass ranges from -0.20% to -0.20% ≤ Δn4 ≤ 0.20%, while the annular width W3 of the inner cladding layer 22 ranges from 0.70 μm to 6.00 μm. The annular width W3 of the inner cladding layer 22 is referenced... Figure 1 This is the difference between the radius R4 of the inner cladding layer 22 and the radius R3 of the first sunken layer 21.

[0061] In one example, a second recessed layer 23 is arranged outside the inner cladding layer 22. The second recessed layer 23 can further reduce macrobending loss. Through simulation and experimentation, the relative refractive index difference Δn5 of the second recessed layer 23 relative to the silica quartz glass ranges from -0.55 ≤ Δn5 ≤ -0.13%, and the annular width W4 of the second recessed layer 23 ranges from 0.80 μm ≤ W4 ≤ 8.40 μm. The annular width W4 of the second recessed layer 23 is referenced... Figure 1 This is the difference between the radius R5 of the second sunken layer 23 and the radius R4 of the inner cladding layer 22.

[0062] In one example, the second recessed layer 23 is surrounded by an outer cladding layer 24. As the outermost layer of cladding 2, the outer cladding layer 24 has a standard radius of 62.5 μm, therefore the radius R6 of the outer cladding layer 24 is also 62.5 μm. However, since the optical fiber may not be standard, the radius R6 of the outer cladding layer 24 may not be 62.5 μm. Regarding the material of the outer cladding layer 24, it is made of the optical fiber's substrate. For example, for glass optical fiber, the outer cladding layer 24 is made of pure silica quartz glass. The outer cladding layer serves to prevent light leakage.

[0063] It should be noted that, structurally, optical fibers not only include the core layer and cladding layer described above, but also a coating layer. The cladding layer surrounds the core layer and serves to confine the light within it. The coating layer surrounds the cladding layer and provides protection. Since the outer cladding layer 24 is the outermost layer of cladding layer 2, the coating layer surrounds the outer cladding layer 24.

[0064] In one example, as described above, the refractive indices of both the first recessed layer 21 and the second recessed layer 23 are less than the refractive index of silica quartz glass. Therefore, the materials of the first recessed layer 21 and the second recessed layer 23 can be boron-doped silica quartz glass, fluorine-doped silica quartz glass, or silica quartz glass that is both fluorine-doped and boron-doped. If the refractive index of the inner cladding layer 22 is less than the refractive index of silica quartz glass, then the material of the inner cladding layer 22 is boron-doped silica quartz glass, fluorine-doped silica quartz glass, or silica quartz glass that is both fluorine-doped and boron-doped. If the refractive index of the inner cladding layer 22 is greater than the refractive index of silica quartz glass, then the material of the inner cladding layer 22 is germanium-doped silica quartz glass.

[0065] It should be noted that the cladding 2 may also include, from the inside out, a first sunken layer 21, an inner cladding 22 and an outer cladding 24, with the second sunken layer 23 not included between the inner cladding 22 and the outer cladding 24.

[0066] Based on the above, the fiber core layer 1 includes an inner core layer 11 and an outer core layer 12. The refractive index of the inner core layer 11 is lower than that of the outer core layer 12, while the refractive index of the outer core layer 12 is greater than that of the silica quartz glass. The design of the refractive indices and radii of the inner core layer 11 and the outer core layer 12 facilitates a larger effective area, a lower cutoff wavelength, and lower macrobending loss in the optical fiber. The cladding 2 includes a first recessed layer 21, an inner cladding layer 22, a second recessed layer 23, and an outer cladding layer 24. The refractive index of the first recessed layer 21 is lower than that of the silica quartz glass, thereby increasing the refractive index between the outer core layer 12 and the first recessed layer 21 to reduce macrobending loss. The refractive indices and radii of the first recessed layer 21, the inner cladding layer 22, the second recessed layer 23, and the outer cladding layer 24 can further adjust the cutoff wavelength and macrobending loss of the optical fiber.

[0067] Through simulation using the finite element simulation software COMSOL and experimental testing, the above design enables the optical fiber to achieve an effective area of ​​150µm at 1550nm. 2 Nearby, or even greater than or equal to 150um 2 With a cutoff wavelength below 1550nm, under the condition of a bending radius of 30mm and 100 bends, its bending loss at a wavelength of 1625nm is less than 0.10dB.

[0068] The following will introduce several types of simulation data.

[0069] (1) The relative refractive index difference Δn1 between the inner core layer 11 and the silica quartz glass is 0.1%, and the radius R1 of the inner core layer 11 is 3.00 μm; the relative refractive index difference Δn2 between the outer core layer 12 and the silica quartz glass is 0.22%, and the radius R2 of the outer core layer 12 is 7.00 μm; the relative refractive index difference Δn3 between the first recessed layer 21 and the silica quartz glass is -0.21%, and the radius R3 of the first recessed layer 21 is 9.00 μm; the relative refractive index difference Δn4 between the inner cladding layer 22 and the silica quartz glass is 0.03%, and the radius R4 of the inner cladding layer 22 is 12.00 μm; the relative refractive index difference Δn5 between the second recessed layer 23 and the silica quartz glass is -0.42%, and the radius R5 of the second recessed layer 23 is 20.00 μm; the radius R6 of the outer cladding layer 24 is 62.5 μm.

[0070] The relationship between the relative refractive index differences of the inner core layer 11, outer core layer 12, first recessed layer 21, inner cladding layer 22, and second recessed layer 23 relative to the silica quartz glass can be found by referring to... Figure 2 As shown, Figure 2 This is a schematic diagram showing the relative refractive index differences between the layers of an optical fiber and the silica quartz glass. The horizontal axis represents the radius, and the vertical axis represents the relative refractive index difference between the layers. (Reference) Figure 2 As shown, the relative refractive index difference Δn1 between the inner core layer 11 and the silica quartz glass, and the relative refractive index difference Δn2 between the outer core layer 12 and the silica quartz glass are both greater than 0. The relative refractive index difference Δn1 between the inner core layer 11 and the silica quartz glass is smaller than the relative refractive index difference Δn2 between the outer core layer 12 and the silica quartz glass, with the outer core layer 12 having the largest relative refractive index difference Δn2. The relative refractive index difference Δn3 between the first recessed layer 21 and the silica quartz glass, and the relative refractive index difference Δn5 between the second recessed layer 23 and the silica quartz glass are both less than zero, with the second recessed layer 23 having the smallest relative refractive index difference Δn5. The relative refractive index difference Δn4 between the inner cladding layer 22 and the silica quartz glass is greater than zero.

[0071] The optical fiber with the above parameter settings has a mode field diameter of 13.91 μm and an effective area of ​​160.87 μm for transmitting an optical signal with a wavelength of 1550 nm. 2 The dispersion of an optical signal with a transmission wavelength of 1550 nm is 21.94 ps / (nm×km), and the dispersion slope is 0.067 ps / (nm×km). 2(×km); the cutoff wavelength of the optical fiber is 1410nm; for an optical signal with a transmission wavelength of 1625nm, under the condition of a bending radius of 30mm and bending 100 times, the corresponding macro-bending loss is 0.021dB; for an optical signal with a transmission wavelength of 1550nm, the corresponding loss is less than 0.18dB / km.

[0072] (2) The relative refractive index difference Δn1 between the inner core layer 11 and the silica quartz glass is 0.17%, and the radius R1 of the inner core layer 11 is 1.00 μm; the relative refractive index difference Δn2 between the outer core layer 12 and the silica quartz glass is 0.21%, and the radius R2 of the outer core layer 12 is 6.90 μm; the relative refractive index difference Δn3 between the first recessed layer 21 and the silica quartz glass is -0.028%, and the radius R3 of the first recessed layer 21 is 8.00 μm; the relative refractive index difference Δn4 between the inner cladding layer 22 and the silica quartz glass is 0.035%, and the radius R4 of the inner cladding layer 22 is 9.00 μm; the relative refractive index difference Δn5 between the second recessed layer 23 and the silica quartz glass is -0.14%, and the radius R5 of the second recessed layer 23 is 17.00 μm; the radius R6 of the outer cladding layer 24 is 62.5 μm.

[0073] The relationship between the relative refractive index differences of the inner core layer 11, outer core layer 12, first recessed layer 21, inner cladding layer 22, and second recessed layer 23 relative to the silica quartz glass can also be referenced. Figure 2 As shown.

[0074] The optical fiber with the above parameter settings has a mode field diameter of 13.56 μm and an effective area of ​​150.45 μm for transmitting an optical signal with a wavelength of 1550 nm. 2 The dispersion of an optical signal with a transmission wavelength of 1550 nm is 21.53 ps / (nm×km), and the dispersion slope is 0.064 ps / (nm×km). 2 (×km); the cutoff wavelength of this optical fiber is 1495nm; for an optical signal with a transmission wavelength of 1625nm, under the condition of a bending radius of 30mm and bending 100 times, the corresponding macro-bending loss is 0.04dB; for an optical signal with a transmission wavelength of 1550nm, the corresponding loss is less than 0.18dB / km.

[0075] (3) The relative refractive index difference Δn1 between the inner core layer 11 and the silica quartz glass is 0.1%, and the radius R1 of the inner core layer 11 is 2.00 μm; the relative refractive index difference Δn2 between the outer core layer 12 and the silica quartz glass is 0.22%, and the radius R2 of the outer core layer 12 is 7.10 μm; the relative refractive index difference Δn3 between the first recessed layer 21 and the silica quartz glass is -0.21%, and the radius R3 of the first recessed layer 21 is 7.50 μm; the relative refractive index difference Δn4 between the inner cladding layer 22 and the silica quartz glass is -0.03%, and the radius R4 of the inner cladding layer 22 is 10.20 μm; the relative refractive index difference Δn5 between the second recessed layer 23 and the silica quartz glass is -0.42%, and the radius R5 of the second recessed layer 23 is 17.60 μm; the radius R6 of the outer cladding layer 24 is 62.5 μm.

[0076] The optical fiber with the above parameter settings has a mode field diameter of 13.55 μm and an effective area of ​​154.93 μm² for transmitting an optical signal with a wavelength of 1550 nm; the dispersion for transmitting an optical signal with a wavelength of 1550 nm is 22.58 ps / (nm×km), and the dispersion slope is 0.066 ps / (nm×km). 2 (×km); the cutoff wavelength of this optical fiber is 1472nm; for an optical signal with a transmission wavelength of 1625nm, under the condition of a bending radius of 30mm and bending 100 times, the corresponding macro-bending loss is 0.012dB; for an optical signal with a transmission wavelength of 1550nm, the corresponding loss is less than 0.18dB / km.

[0077] The relationship between the relative refractive index differences of the inner core layer 11, outer core layer 12, first recessed layer 21, inner cladding layer 22, and second recessed layer 23 relative to the silica quartz glass can be found by referring to... Figure 3 As shown, Figure 3 This is a schematic diagram showing the relative refractive index differences between the layers of an optical fiber and the silica quartz glass. The horizontal axis represents the radius, and the vertical axis represents the relative refractive index difference between the layers. (Reference) Figure 3As shown, the relative refractive index difference Δn1 between the inner core layer 11 and the silica quartz glass, and the relative refractive index difference Δn2 between the outer core layer 12 and the silica quartz glass are both greater than 0. The relative refractive index difference Δn1 between the inner core layer 11 and the silica quartz glass is smaller than the relative refractive index difference Δn2 between the outer core layer 12 and the silica quartz glass, and the relative refractive index difference Δn2 between the outer core layer 12 and the silica quartz glass is the largest. The relative refractive index difference Δn3 of the first recessed layer 21 relative to the silica quartz glass, the relative refractive index difference Δn5 of the second recessed layer 23 relative to the silica quartz glass, and the relative refractive index difference Δn4 of the inner cladding layer 22 relative to the silica quartz glass are all less than zero. Furthermore, the relative refractive index difference Δn3 of the first recessed layer 21 relative to the silica quartz glass and the relative refractive index difference Δn5 of the second recessed layer 23 relative to the silica quartz glass are all less than the relative refractive index difference Δn4 of the inner cladding layer 22 relative to the silica quartz glass. The relative refractive index difference Δn5 of the second recessed layer 23 relative to the silica quartz glass is the smallest.

[0078] (4) The relative refractive index difference Δn1 between the inner core layer 11 and the silica quartz glass is 0.1%, and the radius R1 of the inner core layer 11 is 3.00 μm; the relative refractive index difference Δn2 between the outer core layer 12 and the silica quartz glass is 0.22%, and the radius R2 of the outer core layer 12 is 7.00 μm; the relative refractive index difference Δn3 between the first recessed layer 21 and the silica quartz glass is -0.21%, and the radius R3 of the first recessed layer 21 is 9.00 μm; the relative refractive index difference Δn4 between the inner cladding layer 22 and the silica quartz glass is 0.03%, the radius R4 of the inner cladding layer 22 is 12.00 μm, and the radius R6 of the outer cladding layer 24 is 62.5 μm.

[0079] The relationship between the relative refractive index differences of the inner core layer 11, outer core layer 12, first recessed layer 21, and inner cladding layer 22 relative to the silica quartz glass can be found by referring to... Figure 4 As shown, Figure 4 This is a schematic diagram showing the relative refractive index differences between the layers of an optical fiber and the silica quartz glass. The horizontal axis represents the radius, and the vertical axis represents the relative refractive index difference between the layers. (Reference) Figure 4As shown, the relative refractive index difference Δn1 between the inner core layer 11 and the silica quartz glass, and the relative refractive index difference Δn2 between the outer core layer 12 and the silica quartz glass are both greater than 0. Furthermore, the relative refractive index difference Δn1 between the inner core layer 11 and the silica quartz glass is smaller than the relative refractive index difference Δn2 between the outer core layer 12 and the silica quartz glass, with the outer core layer 12 having the largest relative refractive index difference Δn2. The relative refractive index difference Δn3 between the first recessed layer 21 and the silica quartz glass is less than zero, and the relative refractive index difference Δn4 between the inner cladding layer 22 and the silica quartz glass is greater than zero.

[0080] The optical fiber with the above parameter settings has a mode field diameter of 14.75 μm and an effective area of ​​170.12 μm for transmitting an optical signal with a wavelength of 1550 nm. 2 The dispersion of an optical signal with a transmission wavelength of 1550 nm is 21.94 ps / (nm×km), and the dispersion slope is 0.067 ps / (nm×km). 2 The fiber has a cutoff wavelength of 1471nm; for an optical signal with a transmission wavelength of 1625nm, the macro-bending loss is 0.069dB under the condition of a bending radius of 30mm and 100 bends; the loss for an optical signal with a transmission wavelength of 1550nm is less than 0.18dB / km.

[0081] In this embodiment, the fiber core comprises multiple layers, with the refractive index of each layer increasing sequentially from the inside out. Through simulation and experimental design, the refractive index and radius of each layer are adjusted to achieve a larger effective area and a lower cutoff wavelength. The cladding also comprises multiple layers. The refractive index of the outermost core layer is greater than that of silica glass, while the refractive index of the innermost cladding layer is less than that of silica glass. Through simulation and experimental design, the fiber can achieve a lower macrobending loss. Furthermore, through simulation and experimental design of the refractive index and radius of each cladding layer, the cutoff wavelength and macrobending loss of the fiber can be further adjusted.

[0082] This embodiment also provides an optical transmission system, which includes a transmitter, a receiver and the optical fiber described above, wherein the transmitter and the receiver are connected by multiple optical fiber segments.

[0083] In one example, the optical transmission system can specifically be an optical communication system, where optical fibers transmit optical signals. The transmitter includes a laser and a modulator. The laser is used to generate laser light, and the modulator is used to modulate the laser light into pulsed optical signals. The receiver includes a detector and a demodulator, which is used to receive the optical signals and demodulate the optical signals.

[0084] In another example, the optical transmission system is specifically an energy transmission system used to transmit energy without modulation and demodulation. In this case, the transmitter only includes a laser and does not include a modulator. In this scenario, the optical fiber is used to transmit energy. For example, the transmitter generates a laser, the laser carries energy and is transmitted in the optical fiber, and the receiver receives the laser and converts it into electrical energy.

[0085] The above description is merely an optional embodiment of this disclosure and is not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. An optical fiber, characterized in that, The optical fiber includes a core layer (1) and a cladding layer (2). The core layer (1) includes at least two layers distributed from the inside to the outside. The cladding layer (2) wraps around the core layer (1) and includes a first recessed layer (21) and an inner cladding layer (22) distributed from the inside to the outside. The refractive index of each layer of the core layer (1) increases sequentially from the inside to the outside. The refractive index of the outermost layer of the core layer (1) is greater than the refractive index of any layer in the cladding layer (2). The refractive index of the first recessed layer (21) is less than the refractive index of the inner cladding layer (22).

2. The optical fiber according to claim 1, characterized in that, The outermost layer of the core layer (1) and the first recessed layer (21) are both made of silica quartz glass and doped elements. The refractive index of the outermost layer of the core layer (1) is greater than that of the silica quartz glass, and the refractive index of the first recessed layer (21) is less than that of the silica quartz glass.

3. The optical fiber according to claim 2, characterized in that, The relative refractive index difference Δn3 of the first recessed layer (21) relative to the silica quartz glass ranges from -0.30≤Δn3≤-0.021%, and the annular width W2 of the first recessed layer (21) ranges from 0.30um≤W2≤4.50um.

4. The optical fiber according to any one of claims 1 to 3, characterized in that, The fiber core layer (1) includes an inner core layer (11) and an outer core layer (12), and the materials of the inner core layer (11) and the outer core layer (12) both include silica quartz glass and doped elements; The relative refractive index difference Δn1 between the inner core layer (11) and the silica quartz glass ranges from -0.021% to Δn1 to 0.24%, and the relative refractive index difference Δn2 between the outer core layer (12) and the silica quartz glass ranges from 0.16% to Δn2 to 0.39%.

5. The optical fiber according to claim 4, characterized in that, The radius R1 of the inner core layer (11) is in the range of 0.90um≤R1≤6.0um, and the ring width W1 of the outer core layer (12) is in the range of 1.10um≤W1≤6.00um.

6. The optical fiber according to any one of claims 1 to 5, characterized in that, The material of the inner cladding (22) includes silica quartz glass and doped elements. The relative refractive index difference Δn4 of the inner cladding (22) relative to the silica quartz glass ranges from -0.20% to Δn4 to 0.20%. The ring width W3 of the inner cladding (22) ranges from 0.70um to 6.00um.

7. The optical fiber according to any one of claims 1 to 6, characterized in that, The cladding (2) further includes a second recessed layer (23), which wraps around the inner cladding (22), and the refractive index of the second recessed layer (23) is less than that of the inner cladding (22).

8. The optical fiber according to claim 7, characterized in that, The material of the second recessed layer (23) includes silica quartz glass and doped elements. The relative refractive index difference Δn5 of the second recessed layer (23) relative to the silica quartz glass ranges from -0.55 to -0.13%. The annular width W4 of the second recessed layer (23) ranges from 0.80 μm to 8.40 μm.

9. The optical fiber according to any one of claims 2 to 7 or 8, characterized in that, The doping element in the material with a refractive index greater than that of the silica quartz glass is germanium, and the doping element in the material with a refractive index less than that of the silica quartz glass is at least one of boron and fluorine.

10. The optical fiber according to any one of claims 1 to 9, characterized in that, The cladding also includes an outer cladding layer (24), which is the outermost layer of the cladding layer (2), and the material of the outer cladding layer (24) is silica quartz glass.

11. An optical transmission system, characterized in that, The optical transmission system includes a transmitter, a receiver, and an optical fiber as described in any one of claims 1 to 10, wherein the transmitter and the receiver are connected by multiple optical fiber segments.

Images