CN214278469U - All-solid-state microstructure optical fiber - Google Patents

Abstract

The utility model provides an all-solid-state microstructure optical fiber, including fibre core and micro-structure covering, the fibre core is solid-state quartz fibre core, and the cladding of micro-structure covering is in the periphery of fibre core, the micro-structure covering includes germanium stick and solid-state basement in the regular hexagon dot matrix, and the regular hexagon dot matrix distributes by interior outside and has the multilayer, and the interaxial distance lambda of arbitrary double-phase adjacent point equals in the regular hexagon dot matrix, and the fibre core is located the central point of regular hexagon dot matrix, and many germanium sticks are sparse structure and arrange on each layer regular hexagon dot matrix, and wherein it has solid-state basement to fill between the germanium stick. Because the germanium rods are arranged on each layer of regular hexagonal lattice in a sparse structure, namely, the germanium rods are not arranged on some points on the regular hexagonal lattice, and the positions where the germanium rods are not arranged and gaps among the germanium rods are filled by the solid quartz substrate. Therefore, the bending loss of a high-order mode is increased while the low loss of a signal laser fundamental mode is ensured, so that the quasi-single-mode operation of the optical fiber is realized, and the stimulated Raman scattering can be inhibited.

Description

All-solid-state microstructure optical fiber

Technical Field

The utility model relates to laser fiber technical field, in particular to an all-solid-state microstructure fiber.

Background

The high average power laser has been widely applied to various fields such as metal cutting, material cladding, laser welding, laser ignition and the like by virtue of natural advantages such as energy concentration, flexible conversion, small heat affected zone and the like. In recent years, due to the development of high-brightness pump sources, key optical components, laser materials, pump coupling, beam combining and other technologies, various types of lasers such as high-power fiber lasers, gas lasers, solid-state lasers, semiconductor lasers and the like have made remarkable progress in power enhancement. Taking High Power Fiber Laser (HPFL) as an example, the technology of kilowatt-level fiber oscillators and amplifiers at home and abroad is mature day by day, and the kilowatt-level fiber laser test prototype and industrial products are also successively released and gradually step into the market.

In High Power Laser (HPL) applications, the energy-transmitting fiber provides the possibility of flexible single-mode transmission of the high-power laser beam from the laser source to the work platform. In conventional laser machining applications, for example, a high power laser beam is typically required to transmit several meters, tens of meters, or even hundreds of meters from a light source to a work platform. However, due to the increase of optical power density and the limited area of the optical fiber mode field, high-brightness optical beams in the hundreds of watts or kilowatts inevitably induce nonlinear effects such as Stimulated Brillouin Scattering (SBS), Stimulated Raman Scattering (SRS), etc. when transmitted over long distances. In general, the spectral broadening caused by SBS is the first problem to be solved by narrow-linewidth lasers, and the fluctuation of signal light power and the reduction of efficiency caused by SRS stokes shift are common problems faced by all laser oscillators and amplifiers. Industrial continuous wave HPLs generally have a wide output spectral bandwidth, and thus the primary obstacle limiting their energy transmission fiber length is stimulated raman scattering.

The length and the mode field area of the optical fiber directly determine the threshold power of the SRS, and the requirements are met

Wherein A is_effIs the area of the mode field, g_R(omega) is the Raman gain coefficient, L_effIs the length of the optical fiber. To overcome SRS to achieve long distance transmission of high power laser beams typically requires increasing the core size of the fiber, the so-called Large Mode Area (LMA) fiber. However, the use of LMA fibers inevitably results in multimode operation of the fiber leading to a degradation of the output beam quality. In order to ensure the single-mode operation characteristics of the optical fiber as much as possible, the Numerical Aperture (NA) of the optical fiber is generally required to be reduced with the increase of the core size, and an excessively small NA may result in a high degree of sensitivity of the mode area of the optical fiber to bending, which is not favorable for practical application. Meanwhile, the appearance of some micro-structure fibers such as photonic crystal fibers, leakage channel fibers, multi-core fibers and hollow-core fibers can enable the fibers to have the characteristics of large mode field area, low NA and constant and stable single-mode operation, but the fibers are high in preparation cost, large in transmission loss and bending sensitivity and not suitable for flexible transmission in industrial application generally. With further power increase of HPL, the mode characteristic, the conduction characteristic and the spectral characteristic of the energy transmission fiberAnd mechanical properties are also subject to greater scrutiny.

Therefore, in the context of the application of HPL long-distance quasi-single mode transmission, it is an urgent need for those skilled in the art to design a new energy transmission fiber that can meet the following requirements: (1) the device has larger mode field area and lower bending sensitivity; (2) the control on mode coupling has good high-order mode (HOM) inhibition capability; (3) the capacity of stably transmitting signal wavelength laser and effectively inhibiting SRS wavelength is achieved; (4) the method has tolerance to manufacturing errors, and properly controls the cost and the complexity of the preparation process.

SUMMERY OF THE UTILITY MODEL

The defect to prior art exists, the utility model provides an all solid-state micro-structure optic fibre can be used to high power laser standard single mode long distance transmission and can restrain stimulated raman scattering.

In order to realize the technical purpose, the technical proposal of the utility model is that:

all-solid-state microstructure optical fiber comprises a fiber core and a microstructure cladding, wherein the fiber core is a solid fiber core, the microstructure cladding is coated on the periphery of the fiber core, the microstructure cladding is positioned on germanium rods and a solid substrate in a regular hexagonal lattice, multiple layers of layers are distributed on the regular hexagonal lattice from inside to outside, the central distance lambada between any two adjacent points in the regular hexagonal lattice is equal, the fiber core is positioned at the central position of the regular hexagonal lattice, multiple germanium rods are distributed on each layer of regular hexagonal lattice in a sparse structure, and the solid substrate is filled between the germanium rods. Because the germanium rods are arranged on each layer of regular hexagonal lattice in a sparse structure, namely, the germanium rods are not arranged on some points on the regular hexagonal lattice, and the positions where the germanium rods are not arranged and gaps among the germanium rods are filled by the solid quartz substrate. Therefore, the bending loss of a high-order mode is increased while the low loss of a signal laser fundamental mode is ensured, so that the quasi-single-mode operation of the optical fiber is realized.

As a further improvement of the utility model, the regular hexagon dot matrix has four layers, is first layer regular hexagon dot matrix, second floor regular hexagon dot matrix, third layer regular hexagon dot matrix and fourth floor regular hexagon dot matrix respectively by inside outside.

As the utility model discloses a further improvement, it has the germanium stick to equally divide cloth on 12 points and all points to be equipped with on the first layer regular hexagon dot matrix, it has the germanium stick to equally divide cloth on two points that are equipped with 18 points on the second layer regular hexagon dot matrix and lie in each limit in the middle of, it has the germanium stick to equally divide cloth on four points that are equipped with 24 points on the third layer regular hexagon dot matrix and lie in each limit both ends, it has the germanium stick to equally divide cloth on two points that are equipped with 30 points on the fourth layer regular hexagon dot matrix and lie in each limit both ends and lie in each limit center. Namely, no germanium rod is arranged on the point at the hexagonal vertex in the second layer of regular hexagonal lattice; no germanium rod is arranged at the center of each side in the third layer of regular hexagonal lattice; and the second point and the fourth point of each side in the fourth layer of regular hexagonal lattice are not provided with germanium rods. The gaps between the germanium rods and the positions of the points where the germanium rods are not arranged are filled by the solid quartz substrate. Therefore, the bending loss of a high-order mode is increased while the low loss of a signal laser fundamental mode is ensured, so that the quasi-single-mode operation of the optical fiber is realized.

As a further improvement of the utility model, the fiber core material is solid quartz.

As a further improvement of the utility model, the solid-state substrate adopts a solid-state quartz substrate.

As a further improvement of the present invention, the germanium rod includes a high refractive index germanium-doped region at the center and a low refractive index cladding region at the outer layer, wherein the refractive index of the high refractive index germanium-doped region is a parabolic gradient or step index profile.

As a further improvement of the utility model, the high refractive index germanium-doped region and the low refractive index cladding region of the germanium rod have a refractive index difference delta, which satisfies that delta ═ n_high ²-n_low ²)/(2×n_high ²) Wherein n is_high、n_lowThe refractive index of the high refractive index germanium-doped region is the maximum of the refractive index and the refractive index of the low refractive index cladding region is the refractive index.

As a further improvement of the utility model, the difference delta of the refractive index satisfies that delta is more than or equal to 1.5 percent and less than or equal to 3 percent.

As a further improvement of the present invention, the low refractive index cladding region of the germanium rod may be made of low refractive index material such as solid quartz or Fluorine (Fluorine) -doped solid quartz.

As a further improvement of the utility model, the diameter of each germanium rod is equal.

The utility model provides a micro-structure covering because the anti-resonance coupling and produce the photonic band gap effect, the light beam that gets into the micro-structure covering takes place multiple scattering under the micro-structure effect, and multiple interference between the scattered light makes its intensity weaken and can't pass through the micro-structure covering in the specific frequency range, and the final restriction is transmitted in the fibre core, and this specific frequency range is called as photonic band gap frequency range. Under the condition that the propagation constant is certain, by reasonably setting the structural parameters of the germanium rod, the Stokes wavelength band (1110 nm-1130nm) of the Stimulated Raman Scattering (SRS) falling outside the photonic band gap frequency range is high-loss and cannot be stably transmitted, the light of the signal wavelength band (1060 nm-1080 nm) falling within the photonic band gap frequency range is rejected by the cladding layer to be low-loss, so that the light is well limited to the stable transmission of a fiber core, and a certain spectrum filtering effect is macroscopically shown.

Furthermore, the fiber core material of the present invention is solid quartz. The solid substrate is a quartz substrate.

Further, the utility model discloses the germanium rod that adopts is including the high refractive index germanium-doped zone that is located the center and being located outer low refractive index cladding district, and wherein the refractive index that the high refractive index germanium-doped zone was the distribution of parabola type graded index. The high refractive index germanium-doped region and the low refractive index cladding region have certain core-to-core ratio, and the ratio is arbitrarily set according to requirements, for example, set to be 1: 2.5.

Further, the fiber core of the optical fiber is composed of a single quartz rod or formed by a plurality of quartz rods which are arranged in a periodic and compact mode. The core type is defined as n-cell core, and the core diameter is 4 Λ -d, depending on the number n of silica rods used to form the core.

Compared with the prior art, the beneficial effects of the utility model include at least:

1. all-solid-state microstructure optical fiber utilizes the photonic band gap effect that its microstructure cladding structure itself produced to directly show low restriction loss in laser signal area, and shows high restriction loss at stimulated raman scattering stokes wavelength department, need not just can possess natural stimulated raman scattering suppression effect with the help of other technical means such as crooked, write tilt grating.

2. All solid-state microstructure fiber has the bigger fibre core diameter and mode field area than traditional step index optic fibre (SIF), has promoted the nonlinear effect threshold value rationally, all has certain suppression effect to the nonlinear effect of multiple high power laser including stimulated Raman scattering, stimulated Brillouin scattering etc..

3. All solid-state microstructure optical fiber, because the germanium stick is that sparse structure arranges on each layer regular hexagon dot matrix, do not set up the germanium stick on some points on the regular hexagon dot matrix promptly, the clearance between point position department and the germanium stick that does not set up the germanium stick is filled by solid-state quartz substrate. Therefore, the bending loss of a high-order mode is increased while the low loss of a signal laser fundamental mode is ensured, so that the quasi-single-mode operation of the optical fiber is realized. Specifically, except for a circle of germanium rods which are strictly arranged according to a regular hexagon on each point in the first layer of regular hexagonal lattice close to the fiber core, the germanium rods in the other layers of regular hexagonal lattices are arranged in a sparse structure, namely, the germanium rods are not selectively arranged on some points on the other layers of regular hexagonal lattices, and the positions where the germanium rods are not arranged and gaps among the germanium rods are filled by the solid quartz substrate. Therefore, the bending loss of the high-order mode is far larger than that of the basic mode, so that the high-power laser can be ensured to operate in a quasi-single mode in the transmission process under the condition of a coiling diameter within a certain range.

4. Compare in other types of complicated micro-structure optic fibre such as hollow optic fibre, air hole photonic crystal fiber, micro-structure optic fibre is full solid state structure, and the prefabricated stick preparation and the optic fibre drawing degree of difficulty are lower relatively, and the butt fusion degree of difficulty with laser instrument output tail fiber is lower in the use, is favorable to actual high power laser transmission to be used.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.

FIG. 1 is a schematic cross-sectional view of an all-solid-state microstructured optical fiber according to an embodiment;

FIG. 2 is a schematic diagram of the arrangement of germanium rods in FIG. 1, wherein dotted circles in a regular hexagonal lattice represent the positions of the points where no germanium rods are disposed, and solid circles represent the positions of the points where the germanium rods are disposed;

FIG. 3 is a schematic cross-sectional view of a germanium rod used in one embodiment;

FIG. 4 is a graph showing the refractive index profile of a germanium rod used in example 1;

FIG. 5 is a schematic diagram of the intensity distribution of the eigenmodes of the signal band of the all-solid-state microstructured optical fiber provided in example 1, wherein (a) is LP at a 1070nm signal wavelength of the all-solid-state microstructured optical fiber₀₁Intensity profile of mode mapping, (b) LP at 1070nm signal wavelength for all-solid-state microstructured fiber_11oIntensity profile of mode mapping, (c) LP at 1070nm signal wavelength for all-solid-state microstructured fiber_11eIntensity distribution diagram corresponding to the mode;

fig. 6 is a schematic view of wavelength dependent loss of the all-solid-state microstructured optical fiber provided in example 1 in a straight fiber and a bent state.

Fig. 7 is a graph showing fundamental mode losses at different bend radii for the wavelength of the all-solid-state microstructured optical fiber signal band provided in example 1.

Fig. 8 is a schematic diagram of the fundamental mode and minimum loss high order mode bending losses of the all solid state microstructured optical fiber provided in example 1.

FIG. 9 is a graph showing the refractive index profile of a germanium rod used in example 2;

fig. 10 is a schematic diagram of the wavelength dependent loss and the signal band loss at different bending radii of the all-solid-state microstructured optical fiber provided in example 2 in the straight state.

Fig. 11 is a schematic diagram of the change of the mode field area of the signal band of the all-solid-state microstructured optical fiber provided in example 2 under different bending radii.

Fig. 12 is a schematic diagram of the fundamental mode and minimum loss high-order mode bending losses of the all-solid-state microstructured optical fiber provided in example 2.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.

Referring to fig. 1, the utility model provides an all solid-state microstructure optical fiber, optic fibre includes fibre core and microstructure cladding, and fibre core 1 is solid-state fibre core, and the cladding of microstructure cladding is in the periphery of fibre core 1, the microstructure cladding is including germanium stick 2 and the solid state basement 3 that is arranged in the regular hexagon dot matrix, and the regular hexagon dot matrix distributes by interior outside and has the multilayer, and the centre spacing lambda of arbitrary double-phase adjacent point equals in the regular hexagon dot matrix, and fibre core 2 is located the central point of regular hexagon dot matrix, and many germanium sticks 2 are sparse structure and arrange on each layer regular hexagon dot matrix, and wherein it has solid state basement 3 to fill between the germanium stick 2. Wherein, the materials of the fiber core 1 and the solid substrate 3 are quartz (Silica).

Referring to fig. 1 and 2, the regular hexagonal lattice has four layers, namely a first layer of regular hexagonal lattice, a second layer of regular hexagonal lattice, a third layer of regular hexagonal lattice and a fourth layer of regular hexagonal lattice from inside to outside. Except that a circle of germanium rods are strictly arranged according to a regular hexagon on each point in the first layer of regular hexagonal lattice close to the fiber core, the germanium rods in the other layers of regular hexagonal lattices are arranged in a sparse structure, namely, the germanium rods are not selectively arranged on some points on the other layers of regular hexagonal lattices, and the positions where the germanium rods are not arranged and gaps among the germanium rods are filled by a solid quartz substrate. Therefore, the bending loss of the high-order mode is far larger than that of the basic mode, so that the high-power laser can be ensured to operate in a quasi-single mode in the transmission process under the condition of a coiling diameter within a certain range. Specifically, 12 points are arranged on the first layer of regular hexagonal lattice, germanium rods 2 are uniformly distributed on all the points, 18 points are arranged on the second layer of regular hexagonal lattice, germanium rods 2 are uniformly distributed on two points located in the middle of each side, 24 points are arranged on the third layer of regular hexagonal lattice, germanium rods 2 are uniformly distributed on four points located at two ends of each side, 30 points are arranged on the fourth layer of regular hexagonal lattice, two points located at two ends of each side and two points located in the center of each side are uniformly distributed with germanium rods 2. Namely, no germanium rod is arranged on the point at the hexagonal vertex in the second layer of regular hexagonal lattice; no germanium rod is arranged at the center point of each side in the second layer of regular hexagonal lattice; and no germanium rod is arranged on the second point and the fourth point of each side in the fourth layer of regular hexagonal lattice, as shown in fig. 2, wherein the dotted line dot circles in the regular hexagonal lattice represent the point positions where no germanium rod is arranged, and the solid line dot circles represent the point positions where the germanium rod is arranged.

Example 1:

the structure of the all-solid-state microstructure optical fiber provided in an embodiment of the present invention is shown in fig. 1, and the parameters thereof include: the diameter d of the germanium rod is 4.8 mu m, the central distance Lambda between any two adjacent points in the regular hexagonal lattice is 12 mu m, and the characteristic parameters of the optical fiber

0.4, and a core diameter 4 Λ -d of 43.2 μm. Wherein the fiber core is formed by 7 quartz rods which are periodically and closely arranged.

The cross-sectional structure of the germanium rod used in this embodiment is schematically shown in fig. 3, and the germanium rod 2 includes a high refractive index germanium-doped region 4 at the center and a low refractive index cladding region 5 at the outer layer, wherein the refractive index of the high refractive index germanium-doped region 4 is a parabolic graded index profile, as shown in fig. 4. The outer low-refractive-index cladding region 5 is a quartz cladding. The high refractive index germanium-doped region 4 and the low refractive index cladding region 5 of the germanium rod have a refractive index difference delta, and the refractive index difference delta is (n ═ n)_high ²-n_low ²)/(2×n_high ²) Wherein n is_high、n_lowThe refractive indices of the high index germanium-doped region and the low index cladding region are the maximum and low index, respectively. In this embodiment, the refractive index difference between the central high refractive index germanium-doped region and the outer low refractive index cladding region of the germanium rod is Δ 2%, and the ratio of the diameter of the central high refractive index germanium-doped region to the outer diameter of the outer low refractive index cladding region is 1: 2.5.

The intrinsic mode field distribution of the all-solid-state microstructured optical fiber provided in this embodiment in the signal band is shown in fig. 5, in which (a) is LP of the all-solid-state microstructured optical fiber in 1070nm signal light₀₁Intensity distribution diagram corresponding to mode, (b) LP of all-solid microstructure fiber at 1070nm_11oIntensity distribution diagram corresponding to mode, (c) LP of all-solid microstructure fiber at 1070nm_11eThe intensity distribution of the corresponding mode is shown schematically. The confinement loss of the fiber and the mode field area of the fundamental mode corresponding to each eigenmode at this wavelength are shown in Table 1 below, which shows that the fiber has very low confinement loss to the fundamental mode and a mode field area of 567 μm²Therefore, the optical fiber has to have a larger mode field area and the capability of stably transmitting signal wavelength laser, and meets the basic application requirements of the energy transmission optical fiber.

TABLE 1 effective refractive index and mode field area of fundamental mode for each eigenmode

Specifically, the wavelength-dependent loss of the all-solid-state microstructured optical fiber provided by the above embodiment in the straight optical fiber and 20cm bent state is shown in fig. 6. The loss of a fundamental mode at a signal band can be less than 0.1dB/m and the loss of the fundamental mode at the SRS Toxoks wavelength (1120nm-1130nm) is more than 20dB/m no matter in a straight optical fiber or a bent state, so that the capability of effectively inhibiting at the SRS wavelength is ensured.

Specifically, when signal band wavelength laser light (1060nm and 1070nm are taken as examples) is transmitted in the all-solid-state microstructure optical fiber provided by the above embodiment, the fundamental mode loss at different bending radii (15-20cm) is shown in fig. 7. The bend loss increases slightly with decreasing bend radius, but remains below 0.1dB/m at all times, ensuring lower bend sensitivity of the signal strip.

Specifically, according to the practical application of the all-solid-state microstructure optical fiber provided by this embodiment, in addition to the wavelength-dependent loss, the mode-dependent bending loss during the transmission of the signal band wavelength laser is also considered. Only if the wavelength-dependent loss of the optical fiber is well controlled, the optical fiber can have the SRS restraining function; the quasi-single mode transmission of high power laser can only be achieved if the mode dependent bending losses are controlled well. If the quasi-single mode operation of the optical fiber is to be realized, a larger high-order mode bending loss and a smaller fundamental mode bending loss are required to be ensured at the same time, and the high-order mode possibly existing in the optical fiber is filtered by a bending mode selection method. As shown in fig. 8, the all-solid-state microstructure optical fiber provided in this embodiment can ensure that the bending loss of the fundamental mode of the signal band is less than 0.1dB/m and the bending loss of the high-order mode is greater than 5dB/m under a bending radius of 20cm, wherein the high-order mode loss corresponds to the high-order mode with the minimum calculated loss, and therefore, the high-power laser quasi-single-mode transmission can be ensured to some extent.

Example 2:

the structure of the all-solid-state microstructure optical fiber provided in an embodiment of the present invention is shown in fig. 1, and the parameters thereof include: the diameter d of the germanium rod is 5.3 mu m, the center distance Lambda between any two adjacent points in the regular hexagonal lattice is 13.95 mu m, and the characteristic parameters of the optical fiber

0.38 and a core diameter 4 Λ -d of 50.5 μm. Wherein the fiber core is formed by 7 quartz rods which are periodically and closely arranged.

Specifically, the sectional structure and the refractive index profile of the germanium rod used in this embodiment are shown in fig. 3 and fig. 9, respectively, and the germanium rod 2 includes a high refractive index germanium-doped region 4 located at the center and a low refractive index cladding region 5 located at the outer layer, wherein the refractive index of the high refractive index germanium-doped region 4 has a parabolic graded index profile. The low-index cladding region 5 of the outer layer is a quartz cladding. The high refractive index germanium-doped region 4 and the low refractive index cladding region 5 of the germanium rod have a refractive index difference delta, and the refractive index difference delta is (n ═ n)_high ²-n_low ²)/(2×n_high ²) Wherein n is_high、n_lowThe refractive indices of the high index germanium-doped region and the low index cladding region are the maximum and low index, respectively. In this embodiment, the refractive index difference between the central high refractive index germanium-doped region 5 of the germanium rod and the outer low refractive index cladding region 6 is 1.7%, and the ratio of the outer diameters of the high refractive index germanium-doped region 4 and the low refractive index cladding region 5 of the germanium rod is 1: 2.5.

Specifically, the all-solid-state microstructured optical fiber provided by the present embodiment has a straight fiber wavelength-dependent loss and a 25cm bending state, and the signal band loss is shown in fig. 10. The loss of a fundamental mode at a signal band can be less than 0.1dB/m and the loss of the fundamental mode at the SRS Toxoks wavelength (1120nm-1130nm) is more than 40dB/m no matter in a straight optical fiber or a bent state, so that the capability of effectively inhibiting at the SRS wavelength is ensured.

Specifically, the all-solid-state microstructured optical fiber provided by the present embodiment has the mode field area change of the signal band (1040nm-1070nm) under different bending radii (50cm and 25cm) as shown in fig. 11. Under the bending radius larger than 25cm, the all-solid-state microstructure optical fiber of the embodiment can ensure that the signal band laser is 740 microns²The above mode field area.

Specifically, according to the practical application of the all-solid-state microstructure optical fiber provided by this embodiment, in addition to the wavelength-dependent loss, the mode-dependent bending loss during the transmission of the signal band wavelength laser is also considered. Only if the wavelength-dependent loss of the optical fiber is well controlled, the optical fiber can have the SRS restraining function; the quasi-single mode transmission of high power laser can only be achieved if the mode dependent bending losses are controlled well. If the quasi-single mode operation of the optical fiber is to be realized, a larger high-order mode bending loss and a smaller fundamental mode bending loss are required to be ensured at the same time, and the high-order mode possibly existing in the optical fiber is filtered by a bending mode selection method. As shown in fig. 12, the all-solid-state microstructured optical fiber provided in this embodiment can ensure that the bending loss of the fundamental mode of the signal band is less than 0.1dB/m and the bending loss of the high-order mode is greater than 5dB/m under a bending radius of 20cm, wherein the high-order mode loss corresponds to the high-order mode with the minimum calculated loss, and therefore, the high-power laser quasi-single-mode transmission can be ensured to some extent.

The micro-structure cladding designed by the utility model generates photonic band gap effect due to anti-resonance coupling, and the optical fiber structure designed by the utility model enables the wavelength of the signal light to be positioned on the photonic band gap and the Stokes wavelength to be outside the photonic band gap, so that the all-solid-state micro-structure optical fiber has the characteristics of stable transmission of the signal laser and high inhibition of stimulated Raman scattering; through the arrangement design of the outer-layer germanium rod sparse structure, the bending loss of a high-order mode is increased while the low loss of a signal laser fundamental mode is ensured, so that the all-solid-state microstructure optical fiber has the characteristic of effectively inhibiting the high-order mode, and the quasi-single-mode operation in the high-power laser transmission process is ensured. To sum up, the utility model discloses can satisfy high power laser quasi-single mode long distance application demand, can further guarantee the application effect of high power laser in fields such as medical treatment, industry, national defense.

In summary, although the present invention has been described with reference to the preferred embodiments, it should be understood that the present invention is not limited thereto, and those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention.

Claims (10)

1. The all-solid-state microstructure optical fiber comprises a fiber core and a microstructure cladding, and is characterized in that: the fiber core is solid fiber core, and the cladding of microstructure cladding is in the periphery of fiber core, the microstructure cladding is including germanium stick and the solid state basement that is arranged in the regular hexagon dot matrix, and regular hexagon dot matrix from inside to outside distributes and has the multilayer, and the centre spacing lambda of arbitrary two adjacent points equals in the regular hexagon dot matrix, and the fiber core is located the central point of regular hexagon dot matrix, and many germanium sticks are sparse structure and arrange on each layer regular hexagon dot matrix, and wherein it has the solid state basement to fill between the germanium stick.

2. The all-solid-state microstructured optical fiber according to claim 1, wherein: the regular hexagonal lattice has four layers, and the first layer of regular hexagonal lattice, the second layer of regular hexagonal lattice, the third layer of regular hexagonal lattice and the fourth layer of regular hexagonal lattice are arranged from inside to outside.

3. The all-solid-state microstructured optical fiber according to claim 2, wherein: the first layer of regular hexagonal lattice is provided with 12 points, all the points are uniformly distributed with germanium rods, the second layer of regular hexagonal lattice is provided with 18 points, two points positioned in the middle of each edge are uniformly distributed with germanium rods, the third layer of regular hexagonal lattice is provided with 24 points, four points positioned at two ends of each edge are uniformly distributed with germanium rods, and the fourth layer of regular hexagonal lattice is provided with 30 points, two points positioned at two ends of each edge and two points positioned at the center of each edge are uniformly distributed with germanium rods.

4. An all-solid-state microstructured optical fiber according to claim 1, 2 or 3, characterized in that: the core material is solid quartz.

5. The all-solid-state microstructured optical fiber according to claim 3, wherein: the solid substrate is a solid quartz substrate.

6. An all-solid-state microstructured optical fiber according to claim 1, 2, 3 or 5, characterized in that: the germanium rod comprises a high-refractive-index germanium-doped region positioned in the center and a low-refractive-index cladding region positioned on the outer layer, wherein the refractive index of the high-refractive-index germanium-doped region is in parabolic graded or step-type refractive index distribution.

7. The all-solid-state microstructured optical fiber according to claim 6, wherein: the high refractive index germanium-doped region and the low refractive index cladding region of the germanium rod have a refractive index difference delta, and the refractive index difference delta is (n)_high ²-n_low ²)/(2×n_high ²) Wherein n is_high、n_lowThe refractive index of the high refractive index germanium-doped region is the maximum of the refractive index and the refractive index of the low refractive index cladding region is the refractive index.

8. The all-solid-state microstructured optical fiber according to claim 7, wherein: the refractive index difference delta is more than or equal to 1.5 percent and less than or equal to 3 percent.

9. The all-solid-state microstructured optical fiber according to claim 6, wherein: the low index cladding region of the germanium rod is made of solid quartz or fluorine doped solid quartz.

10. An all-solid-state microstructured optical fiber according to claim 1, 2, 3, 5, 7, 8 or 9, characterized in that: the germanium rods are of equal diameter.

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