CN104865637B - A kind of stimulated Brillouin scattering effect enhanced fiber - Google Patents

Abstract

The invention discloses a stimulated Brillouin scattering effect-enhanced optical fiber, which includes a core and a cladding surrounding the core; wherein, the core radius a of the optical fiber is 1 μm to 7 μm, and the fiber core is doped with GeO ₂ , One of P ₂ O and Al ₂ O ₃ ; the cladding dopant is F; the relationship between the refractive index difference Δn between the core and the cladding and the core radius a is: 0<a ² Δn≤ 0120μm ² ; the relationship between the acoustic velocity difference ΔV _l between the core and the cladding and the core radius a is: 0<a ² ΔV _l ≤225μm ² ·m/s, to generate stable excitation in the fiber at the same time Single optical mode and single acoustic mode are bound; different doping in the fiber core and cladding can obtain the co-excitation of the acousto-optic field, and coupling in the fiber forms a single Brillouin gain peak; the gain spectrum of the fiber provided by the invention The position of the gain peak has a higher gain coefficient, and the full width at half maximum of the Brillouin gain spectrum is narrow, about 10MHz; and while enhancing the stimulated Brillouin scattering effect, it can also increase the absolute value of the dispersion parameter of the fiber. The four-wave mixing effect is effectively suppressed near the working wavelength window of 1.55μm.

Description

A Stimulated Brillouin Scattering Enhanced Optical Fiber

technical field

The invention belongs to the field of optical fiber technology, and more specifically relates to a stimulated Brillouin scattering effect enhanced optical fiber.

Background technique

The gain spectrum bandwidth of stimulated Brillouin scattering in optical fiber is very narrow (about 10MHz). Using this narrow bandwidth gain spectrum characteristic, it can be used to construct an active optical filter with high Q parameters to extract specific wavelength components of the measured signal , has a wide range of applications in ultra-high resolution spectral analysis, microwave photon filtering and other fields. When applied in these fields, the filter should have a narrow passband bandwidth, high isolation and a single-peak transmission curve; therefore, the optical fiber used to form an active optical filter with a high Q parameter should have a Brillouin The narrow bandwidth of the gain spectrum, high gain factor and single gain peak are featured.

Journal literature (Koyamada Y, Sato S, Nakamura S, et al. Simulating and designing Brillouin gain spectrum in single-mode fibers [J]. Journal of Lightwave Technology, 2004, 22 (2): 631.), discloses the core doped GeO2 The Brillouin gain spectrum of an optical fiber clad with pure silica at a wavelength of 1.55 μm. The single-mode optical fiber mentioned in this document has multiple Brillouin gain peaks.

The patent document with the application number CN 101174002 B discloses a nonlinear optical fiber. By reducing the effective area of the optical field in the optical fiber, the nonlinear constant in the optical fiber is increased, so that self-phase modulation, cross-phase modulation and four-wave mixing The non-linear effects such as are enhanced; but for the Brillouin scattering benefit spectrum, the optical fiber disclosed in this patent document cannot meet the performance of the aforementioned high-Q parameter active optical filter application.

Contents of the invention

In view of the above defects or improvement needs of the prior art, the present invention provides a stimulated Brillouin scattering effect-enhanced optical fiber, the purpose of which is to use different types of doping for the core and cladding to excite a single acoustic mode and a single light The Brillouin gain spectrum with a single gain peak is generated through the coupling between the acousto-optic modes to meet the requirements of optical fibers for constructing high-Q parameter active optical filters.

In order to achieve the above object, according to one aspect of the present invention, a stimulated Brillouin scattering effect-enhanced optical fiber is provided, with a bandwidth of 10 MHz, including a core and a cladding surrounding the core;

Wherein, the core radius a of the optical fiber is 1 μm to 7 μm; wherein, the fiber core is doped with one of GeO ₂ , P ₂ O ₅ and Al ₂ O ₃ ; the cladding is doped with F;

In order to obtain high-efficiency coupling of single optical mode and single acoustic mode, adjust the fiber doping material and concentration so that the relationship between the difference Δn between the refractive index of the core and the refractive index of the cladding and the radius a of the core satisfies 0<a ² Δn≤ 0.120, the difference between the acoustic velocity of the fiber core and the acoustic velocity of the cladding ΔV _l and the radius of the fiber core satisfy 0<a ² ΔV _l ≥ 225μm ² m/s; a single optical mode and a single acoustic mode can be generated by simultaneous and stable excitation in the fiber Confinement; Different doping in the fiber core and cladding can obtain co-excitation of the acousto-optic field, and coupling in the fiber forms a single Brillouin gain peak.

Preferably, the core radius a is 3 μm to 7 μm, the core is doped with GeO ₂ , the cladding is doped with F; the doping concentration of the core GeO ₂ Satisfy The cladding F doping concentration ω _F satisfies:

By doping the core with GeO ₂ , doping the cladding with F and constraining each doping concentration within the above range, the stable excitation of single optical mode and single acoustic mode in the fiber is obtained, and the Brillouin gain spectrum of a single gain peak is obtained.

Preferably, the core radius a is 1 μm to 3 μm, the core is doped with GeO ₂ , the cladding is doped with F, and the core GeO ₂ doping concentration is Satisfy The cladding F doping concentration ω _F satisfies

By reducing the fiber diameter, the effective area of the light field in the fiber is reduced, and the coupling efficiency of the acousto-optic field is improved, thereby increasing the gain coefficient at the gain peak of the Brillouin gain spectrum in the fiber.

Preferably, for the optical fiber whose core radius a is 1 μm to 3 μm, its core _GeO2 doping concentration satisfies the relationship: Core _GeO2 doping concentration If the value is selected within this range, the phonon lifetime in the fiber can be increased, and the bandwidth of the Brillouin gain spectrum in the fiber can be reduced.

Preferably, the optical fiber includes a core, an inner cladding and an outer cladding; the inner cladding covers the core, and the outer cladding covers the inner cladding;

Wherein, the core radius a of the optical fiber is 1.5 μm to 3 μm, and the relationship between the outer diameter b of the inner cladding of the optical fiber and the core radius a of the optical fiber is b=(1.6±0.05)a;

Among them, the fiber core doping is one of GeO ₂ , P ₂ O ₅ and Al ₂ O ₃ ; the inner cladding and the outer cladding are doped with the same material, which is F;

Adjust the doping material and concentration of the fiber core and the outer cladding, so that the refractive index of the fiber core and the outer cladding satisfies the relationship 0<a ² Δn≤0.120μm ² , and the acoustic velocity of the fiber core and the outer cladding satisfies the relationship 0<a ² ΔV _l ≤225μm ² m/s to obtain efficient coupling of single optical mode and single acoustic mode;

Adjust the doping concentration of the fiber cladding so that the relationship between the refractive index n ₁ of the fiber cladding and the refractive index n ₂ of the outer cladding satisfies 0<n ₂ -n ₁ <0.007, and the acoustic velocity v _l1 of the cladding and the acoustic velocity v of the fiber core The relationship between _l satisfies 0<a ² (v _l1 -v _l )≤225μm ² ·m/s.

Preferably, the radius a of the core is 1.5 μm to 3 μm, the core is doped with GeO ₂ , both the inner cladding and the outer cladding are doped with F, and the doping concentration of the core GeO ₂ is Satisfy: The outer cladding F doping concentration ω _F satisfies: Inner cladding F doping concentration ω _{F inside} satisfies ω _{F inside} ≤ ω _{F outside} + 1.4549 and The above-mentioned double-clad optical fiber with inner cladding and outer cladding has a large absolute value of fiber dispersion at the working wavelength window of the fiber, which effectively suppresses the four-wave mixing effect in the fiber and avoids excessive refractive index Differential excitation of high-order modes of the optical field produces a multi-peaked Brillouin gain spectrum.

Generally speaking, compared with the prior art, the above technical solutions conceived by the present invention can achieve the following beneficial effects:

(1) In the stimulated Brillouin scattering effect-enhanced optical fiber provided by the present invention, by adjusting the core radius and doping parameters, the optical field and acoustic field excitation in the optical fiber meet the single-mode condition, and the acousto-optic mode The coupling of produces a Brillouin gain spectrum with only a single gain peak, and the gain spectrum has a high gain coefficient;

(2) In the preferred scheme of a stimulated Brillouin scattering effect-enhanced optical fiber provided by the present invention, by reducing the fiber core radius to obtain a smaller effective area of the optical field, the effect of efficient coupling of the acousto-optic field is achieved, Significantly improve the fiber Brillouin gain coefficient and maintain the gain spectrum bandwidth within 20MHz;

(3) In the preferred scheme of a stimulated Brillouin scattering effect-enhanced optical fiber provided by the present invention, an optical fiber with a double-clad structure of an inner cladding and an outer cladding is provided, and by adjusting the doping concentration of the inner cladding, Change the fiber waveguide dispersion, thereby changing the overall dispersion of the fiber, making the absolute value of the dispersion value at the working wavelength window of the fiber larger, effectively suppressing the four-wave mixing effect in the fiber; to suppress the four-wave mixing effect in the fiber to the filter The distortion effect of the measured signal brought by the application.

Description of drawings

Fig. 1 is a schematic diagram of the relationship between various parameters in an optical fiber;

Fig. 2 is a Brillouin gain spectrum simulation curve diagram in a common single-mode fiber;

Fig. 3 is the simulation graph of Brillouin gain spectrum in the double-doped optical fiber that embodiment 1 provides;

Figure 4 is a comparison chart of the bandwidth, gain coefficient, and Brillouin frequency of optical fibers under different fiber diameters;

Figure 5 shows the dispersion curves and zero dispersion wavelengths of different types of optical fibers at a wavelength of 1.55 μm;

Fig. 6 is the double-clad fiber Brillouin gain spectrum simulation figure provided by embodiment 26 and embodiment 27;

Fig. 7 is a cross-sectional structure diagram of the fiber layer refractive index of the optical fiber provided by the present invention;

Fig. 8 is a cross-sectional structure diagram of the fiber layer acoustic velocity of the optical fiber provided by the present invention.

detailed description

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not constitute a conflict with each other.

Figure 1 is a schematic diagram of the relationship between the material and structural parameters in the optical fiber and the gain spectrum characteristics of the stimulated Brillouin dispersion. The bandwidth, gain coefficient and number of peaks of the Brillouin gain spectrum in the fiber are affected by the phonon lifetime, the coupling efficiency of the acousto-optic field and the number of excited acousto-optic field modes in the fiber, while the phonon lifetime, the coupling efficiency of the acousto-optic field and The number of excited acousto-optic field modes is determined by the fiber dopant material and concentration, fiber core radius, cladding structure, etc.; the following will further elaborate through specific examples.

Example 1,

The optical fiber provided by embodiment 1 comprises a core and a cladding surrounding the core;

Among them, the core radius a is 3 μm, the core doping Ge concentration is 1.646%, and the core refractive index is 1.4616; the cladding doping F concentration is 0.335%, and the cladding refractive index is 1.4551;

The above fiber doping concentration and fiber core radius make there only one form of optical field in the optical fiber, and the optical field parameter a ² Δn is 0.036 μm ² ; corresponding to the only β _acoustic ; where β _acoustic is the direction of the fiber axis of the acoustic vector weight;

For the optical fiber provided in Example 1, due to the fiber doping effect, the acoustic velocity difference between the core and the cladding is ΔV _l of 16.6 m/s; therefore a ² ΔV _l = 149.6 μm ² ·m/s, which is different from that of a common single Compared with single-mode fiber, a ² ΔV _l is an order of magnitude smaller, and it is a single-acoustic-mode fiber; the mutual coupling of single optical mode and single-acoustic mode makes the Brillouin gain spectrum in the fiber a single peak; the Brillouin frequency shift is 11.06GHz, Brillouin gain spectrum full width at half maximum is 11.5MHz;

Figure 2 is a simulation curve of the Brillouin gain spectrum of a common single-mode fiber. FIG. 3 is a simulated graph of the Brillouin gain spectrum of the double-doped fiber provided in Embodiment 1. Comparing Fig. 3 with Fig. 2, it can be seen that there is only one Brillouin gain spectrum peak in the single-mode fiber provided by Embodiment 1.

Table 1 lists the parameters of the optical fibers provided in Embodiment 1 to Embodiment 13. The * symbol in Table 1 means that there are two Brillouin gain peaks, but the gain coefficient of the second peak is much smaller than the main peak and can be ignored; the details are as follows:

Table 1 The parameters of the optical fiber provided by embodiment 1 to embodiment 13

From the analysis of the data provided in Table 1, it can be concluded that the optical fibers provided in Examples 1 to 13 can simultaneously and stably excite a single optical mode and a single acoustic mode, and a single gain peak is formed after the single optical mode and single acoustic mode are coupled. The Brillouin gain spectrum; the optical fiber provided in embodiment 2, although there are two Brillouin gain peaks, the gain coefficient of the second peak is much smaller than that of the main peak, and the influence of the second peak on the gain spectrum can be ignored, which is regarded as a specific single gain peak.

Example 14,

The optical fiber provided by Embodiment 14 includes a core and a cladding surrounding the core;

Among them, the core radius a is 2 μm, the core doping Ge concentration is 3.704%, and the refractive index is 1.4634; the cladding layer doping F concentration is 0.748%, and the refractive index is 1.4544; the optical field is a single-mode characteristic, and the parameter a ² Δn is 0.0364μm ² , corresponding to the only β _acoustic ; the fiber doping effect makes the acoustic velocity difference between the core and the cladding ΔV _l 38.4m/s, and a ² ΔV _l = 153.6μm ² ·m/s;

Compared with the optical fiber provided by embodiment 1, the optical fiber provided by embodiment 14 has a sound velocity difference ΔV ₁ between the core and the cladding that is about 3 times higher than that of the optical fiber of embodiment 1, but the fiber core radius is reduced to 2/3 of the core radius in Example 1; the acoustic field normalization parameter a ² ΔV _l of the optical fiber provided in Example 14 remains basically unchanged, showing a monophonic mode characteristic;

According to the simulation results, the Brillouin frequency shift of the optical fiber provided by Embodiment 14 is 10.91 GHz, and the full width at half maximum is 13.0 MHz; it is set that the fiber core radius provided by Embodiment 1 is that the fiber gain coefficient maximum value of 3 μm is 1, then the embodiment The gain coefficient of the fiber with a core radius of 2 μm provided by 14 is 2.1689; the Brillouin gain coefficient of the fiber in Example 14 is significantly improved, and the fiber has a higher isolation when used as an active optical filter.

Example 15,

The optical fiber provided by Embodiment 15 includes a core and a cladding surrounding the core;

Among them, the core radius a is 1.5 μm, the core doping Ge concentration is 6.584%, and the refractive index is 1.4676; the cladding F doping concentration is 1.330%, and the refractive index is 1.4516; the parameter a ² Δn is 0.036 μm ² , corresponding to The parameter a ² ΔV _l = 153.7μm ² ·m/s between the acoustic velocity difference of the core cladding and the core radius due to the only fiber doping effect;

Compared with embodiment 1 and embodiment 14, the optical fiber provided by embodiment 15 has a reduced core radius, while the sound velocity difference between the core and the cladding further increases; the acoustic velocity difference of the optical fiber provided by embodiment 15 is about It is 7 times that in Example 1, and the sound field normalization parameter a ² ΔV _l is basically unchanged, so the sound field is also a single-mode characteristic; the Brillouin gain spectrum is a single peak, and the Brillouin frequency shift is 10.67GHz, half The high full width is 15.0MHz; the fiber core radius that setting embodiment 1 provides is that the fiber gain coefficient maximum value of 3 μ m is 1, and then the fiber core radius that embodiment 15 provides is that the fiber gain coefficient of 1.5 μ m is 3.8472, comparative analysis finds out, implements The Brillouin gain coefficient of the fiber in Example 15 is larger than that in Example 14, and the isolation is further improved when the fiber is used in an active optical filter.

As shown in Figure 4 is the bandwidth, gain coefficient, Brillouin frequency contrast chart of the optical fiber in embodiment 1, embodiment 14 and embodiment 15, as can be seen from the figure, as the fiber core diameter decreases, the fiber gain coefficient Significantly improved, the Brillouin frequency decreases, but the bandwidth of the Brillouin gain spectrum increases;

On the other hand, due to the increase of the doping concentration of the core GeO ₂ , the lifetime of the phonon in the fiber decreases, and the full width at half maximum of the Brillouin gain spectrum of the fiber is related to the lifetime of the phonon, and the bandwidth of the Brillouin gain spectrum of the fiber increases with The doping concentration of the fiber core GeO ₂ increases and increases, so the gain coefficient and bandwidth must be compromised while reducing the core diameter; the bandwidth is between 10MHz and 15MHz, and the Brillouin gain spectrum gain coefficient and bandwidth of the fiber are balanced;

Table 2 lists the parameters of the optical fibers provided by Embodiment 14 to Embodiment 25, wherein the Brillouin gain coefficient is based on Embodiment 1, as follows:

The parameters of the optical fiber provided by Table 2 embodiment 14～embodiment 25

From the analysis in Table 2, the Brillouin gain coefficient gradually increases with the decrease of the core radius; with the decrease of the core radius and the increase of the doping concentration, the phonon lifetime in the fiber decreases and the gain spectrum bandwidth increases; Through the comparative analysis of the data in Table 2, it can be seen that in the case of similar core radii, reducing the doping concentration of the core can effectively reduce the Brillouin gain spectrum bandwidth of the fiber.

Adjusting the fiber structure and doping concentration may lead to the enhancement of the four-wave mixing effect while realizing the enhancement of the Brillouin gain coefficient. In practical application, when the optical signal has multiple cycles and the interval is small, the four-wave mixing effect directly affects the use effect of the active optical filter and the accuracy of signal measurement and processing.

For the double-doped optical fiber with a core radius of 2 μm provided in Example 14, its dispersion value is zero at a wavelength of 1.5625 μm, and the dispersion value is in the band from 1.1 μm to 1.7 μm, and the absolute dispersion value at a wavelength of 1.1 μm is The maximum value is about -38ps/km/nm; in particular, the waveguide dispersion of this fiber reaches the maximum value of negative dispersion at 1.57μm, about -26ps/km/nm, and the minimum value of negative dispersion is at 1.1μm, about -16.7ps /km/nm;

The optical fiber with a working wavelength near 1.55 μm can effectively stimulate the single-peak Brillouin gain spectrum, but because the dispersion at 1.55 μm is -0.78728 ps/km/nm, it is easy to produce four-wave mixing effect; In the application of the source optical filter, the measurement and processing of the signal may be distorted due to the four-wave mixing; the double-clad structure can effectively eliminate the distortion caused by the four-wave mixing effect.

Example 26,

The optical fiber provided in Embodiment 26 includes a core, an inner cladding covering the core, and an outer cladding covering the inner cladding;

Among them, the core radius a is 2 μm, the cladding outer diameter b is 3.3 μm, and the outer cladding outer diameter is 90 μm; the core doping Ge concentration is 4.1152%, and the refractive index is 1.464; the cladding doping F concentration is 0.83136%, The refractive index is 1.454; the concentration of F doped in the outer cladding is 0.62352%, and the refractive index is 1.455;

For the optical fiber provided in Example 26, its Brillouin gain spectrum is multi-peak, the main peak frequency is 10.87 GHz, and the secondary peak frequency is 10.96 GHz, wherein the gain of the secondary peak is two orders of magnitude smaller than that of the main peak;

For the fiber provided in Example 26, the wavelength at the zero point of dispersion is about 1.61 μm. Compared with the dual-doped fiber with a core of 2 μm provided in Example 14, the zero point of dispersion moves to the long wavelength direction; between 1.1 μm and 1.7 In the μm band, the absolute value of dispersion is the largest at the wavelength of 1.1μm, about -40ps/km/nm;

The waveguide dispersion of the optical fiber provided in Example 26 reaches the maximum value of negative dispersion at 1.53 μm, about -30 ps/km/nm, and the minimum value of negative dispersion at 1.1 μm, about -19 ps/km/nm; the working wavelength is 1.55 At μm, the dispersion of the fiber is -4.34198ps/km/nm;

From the above analysis of the dispersion parameters of the optical fiber in Example 26, it can be seen that the double-clad structure makes the negative dispersion value of the optical fiber waveguide dispersion larger, the zero dispersion point of the optical fiber moves to the long wavelength direction, and the zero dispersion point of the optical fiber drifts beyond the working band ; But compared with Example 14, the single-acoustic mode characteristic of the optical fiber becomes multi-acoustic mode, and the Brillouin gain spectrum becomes a bimodal characteristic.

Example 27,

The optical fiber provided in Embodiment 27 includes a core, a cladding covering the core, and an outer cladding covering the cladding;

Among them, the fiber core radius a is 2 μm, and the cladding outer diameter b is 3.3 μm; among them, the core doping Ge concentration is 4.1152%, and the refractive index is 1.464; the cladding doping F concentration is 1.0392%, and the refractive index is 1.453 , the concentration of F doped in the outer cladding is 0.62352%, and the refractive index is 1.455;

The optical fiber provided in Example 27 has a Brillouin frequency of 10.86 GHz; the wavelength at its zero point of dispersion is about 1.64 μm, and compared to Example 26, its zero point of dispersion moves further to a longer wavelength; in the band from 1.1 μm to 1.7 μm Among them, the maximum absolute value of dispersion appears in the 1.1μm band, where the absolute value of dispersion is about -43ps/km/nm;

The negative dispersion value of its waveguide dispersion reaches the maximum at the wavelength of 1.51μm, which is about -35ps/km/nm. At the wavelength of 1.1μm, the minimum value of the negative dispersion value of the waveguide dispersion of the optical fiber is about -22ps/km/nm; at work At the wavelength of 1.55μm, the total dispersion of the fiber is -8.10925ps/km/nm;

Compared with Example 26, the absolute value of the dispersion of the optical fiber provided by Example 27 is larger at the working wavelength of 1.55 μm, and the effect of suppressing the four-wave mixing effect in the optical fiber is achieved; compared with Example 26, Example 27 has no sub-peak influences;

Shown in Fig. 5 is the dispersion curve and the zero dispersion wavelength of the optical fiber that embodiment 14, embodiment 26 and embodiment 27 provide at 1.55 μ m wavelength; Double-clad structure, and optimize the doping of the inner cladding of the fiber, so that the absolute value of the dispersion at the wavelength of 1.55 μm becomes larger, which suppresses the four-wave mixing effect in the fiber; in addition, the dispersion zero point in the fiber The value moves to the direction of long wavelength, which makes the use of optical fiber work in a wider band.

Figure 6 is the Brillouin gain spectrum simulation diagram of embodiment 26 and embodiment 27; as can be seen from the figure, the double-clad structure of embodiment 26 destroys the single-peak characteristic of the gain spectrum, but by optimizing the inner cladding of the optical fiber The doping concentration makes the secondary peaks in the Brillouin gain spectrum gradually decrease or even disappear, and can make the absolute value of the fiber dispersion larger in the common 1.55μm working wavelength window.

Figure 7 is the fiber layer refractive index cross-sectional structure diagram of embodiment 26 and embodiment 27, wherein r is the distance along the radial direction of the fiber cross section, a is the fiber core radius, b is the outer diameter of the inner cladding of the fiber, and n is the fiber Core refractive index, n ₁ is the refractive index of the inner cladding of the fiber, and n ₂ is the refractive index of the outer cladding of the fiber; the refractive index between the core of the fiber and the inner cladding and the outer cladding ensures that the fiber has and only one light field distribution; in addition, In the double-clad structure, a cladding close to the core enables the dispersion region of the fiber to effectively avoid the influence of other nonlinear effects caused by the small dispersion at the working wavelength of the fiber.

Figure 8 is the fiber layer acoustic velocity profile structure diagram of embodiment 26 and embodiment 27, wherein r is the distance along the radial direction of the fiber cross section, wherein a is the fiber core radius, b is the inner cladding outer diameter of the fiber, v _l is the acoustic velocity of the fiber core, v _l1 is the acoustic velocity of the inner cladding of the fiber, and v _l2 is the acoustic velocity of the outer cladding of the fiber; the relationship between the acoustic velocity between the core of the fiber and the two claddings ensures that the stable excitation of the fiber produces a single acoustic mode , the coupling between the acousto-optic modes yields a single Brillouin gain spectrum.

The optical fiber provided by Embodiment 27 can be fully excited to form a single-peak Brillouin gain spectrum, which has high isolation, and the full width at half maximum of the gain spectrum is narrow, about 10MHz; while the Brillouin gain spectrum is enhanced, it also The absolute value of the dispersion parameter of the optical fiber can be increased, and the four-wave mixing effect can be effectively suppressed near the wavelength of 1.55 μm.

Table 3 lists the parameters of the optical fibers provided by Embodiment 28 to Embodiment 31, specifically as follows:

Table 3 The parameters of the optical fiber provided by embodiment 28～embodiment 31

The core radius a of embodiment 28 and embodiment 29 is 1.5 μ m, and embodiment 28 has only one cladding layer, and embodiment 29 has inner cladding layer and outer cladding layer; The fiber core radius a of embodiment 30 and embodiment 31 is 3 μ m, Example 30 has only one cladding, and Example 31 has an inner cladding and an outer cladding; from comparative analysis of data, it can be known that the double cladding can change the dispersion of the fiber, so that the fiber can effectively suppress the four-wave mixing effect at a specific wavelength.

It is easy for those skilled in the art to understand that the above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, All should be included within the protection scope of the present invention.

Claims (6)

1. A stimulated Brillouin scattering effect-enhanced optical fiber, comprising a core and a cladding around the core; The core radius a is 1 μm to 7 μm; the fiber core is doped with one of GeO ₂ , P ₂ O ₅ and Al ₂ O ₃ , and the cladding is doped with F; The relationship between the difference Δn between the refractive index of the core and the cladding and the radius a of the core is: 0<a ² Δn≤0.120 μm ² , the difference ΔV _l between the acoustic velocity of the core and the cladding The relationship with the fiber core radius a is: 0<a ² ΔV _l ≤225μm ² m/s, so as to simultaneously excite and generate single optical mode and single acoustic mode confinement in the fiber, the single optical mode and single acoustic mode The Brillouin gain spectrum of a single gain peak formed by coupling in an optical fiber. 2. The optical fiber according to claim 1, wherein the core radius a is 3 μm to 7 μm; the core is doped with GeO ₂ , and the cladding is doped with F; The core _GeO2 doping concentration The relationship between and the core radius a is: The cladding F doping concentration ω _F is related to the core radius a and the core GeO ₂ doping concentration The relationship between is: 3. The optical fiber according to claim 1, wherein the core radius a is 1 μm to 3 μm; the core is doped with GeO ₂ , and the cladding is doped with F; The core _GeO2 doping concentration The relationship between and the core radius a is: The cladding F doping concentration ω _F is related to the core radius a and the core GeO ₂ doping concentration The relationship between is: 4. optical fiber as claimed in claim 3, is characterized in that, described fiber core _GeO Doping concentration for: 5. The optical fiber according to claim 3, wherein the cladding comprises an inner cladding and an outer cladding; the inner cladding covers the core, and the outer cladding covers the inner cladding; The core radius a is 1.5 μm to 3 μm, and the relationship between the inner cladding outer diameter b and the core radius a is: b=(1.6±0.05)a; The relationship between the refractive index difference Δn between the core and the outer cladding and the core radius a is: 0<a ² Δn≤0.120 μm ² ; the acoustic velocity difference ΔV _l between the core and the outer cladding and The relationship between the core radius a is: 0<a ² ΔV _l ≤225μm ² ·m/s; The relationship between the inner cladding refractive index n ₁ and the outer cladding refractive index n ₂ is: 0<n ₂ -n ₁ <0.007; the inner cladding acoustic velocity v _l1 is related to the core acoustic velocity v _l and the core radius The relationship between a is: 0<a ² (v _l1 -v _l )≤225μm ² ·m/s. 6. The optical fiber according to claim 5, wherein the core is doped with GeO ₂ , and both the inner cladding and the outer cladding are doped with F; The core _GeO2 doping concentration The relationship between and the core radius a is: The relationship between the _outer cladding F doping concentration ω Fouter and the core _GeO2 doping concentration is: The relationship between the inner cladding F doping concentration ω _F and the outer cladding doping concentration and core _GeO doping concentration is respectively: ω _{F inner} ≤ ω _{F outer} +1.4549,