CN112505823B - Optical fiber type tunable broadband mode converter and preparation method thereof - Google Patents
Optical fiber type tunable broadband mode converter and preparation method thereof Download PDFInfo
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- G02B6/02057—Optical fibres with cladding with or without a coating comprising gratings
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- G02B6/02152—Refractive index modulation gratings, e.g. Bragg gratings characterised by the method of manufacture of the grating involving moving the fibre or a manufacturing element, stretching of the fibre
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- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
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Abstract
The invention discloses a lightThe fiber type tunable broadband mode converter is characterized in that the converter is uniformly thinned to a preset fiber core radius R n The long-period fiber grating with the preset non-uniform period characteristic is manufactured on the few-mode fiber. The invention has high compatibility, tunable broadband, flat conversion and simple and easy realization of the manufacturing process.
Description
Technical Field
The invention relates to the technical field of optical fiber communication and optical fiber sensing, in particular to an optical fiber type tunable broadband mode converter and a preparation method thereof.
Background
Nowadays, rapid development and popularization of internet technology bring about rapid increase of information traffic, and rapid development of big data, cloud computing, mobile internet, and various network applications make demand for network transmission capacity exponentially increase. The optical fiber communication network is a backbone network of a modern information network, the space division/mode division multiplexing technology is combined with the wavelength division multiplexing technology, the capacity of optical fiber communication can be greatly improved, and the optical fiber communication network is a key technology for realizing future large-capacity optical fiber communication. The optical fiber type mode converter, especially the optical fiber type mode converter capable of realizing high-efficiency high-order optical fiber mode conversion, is a main device of an optical fiber mode division multiplexing system, has the advantages of small volume, low cost, simple structure and the like, and can be better matched with the existing optical fiber devices and optical fiber networks. In an all-fiber mode division and wavelength division hybrid multiplexing network, a mode division multiplexing technology needs to be combined with a dense wavelength division multiplexing system which is widely used at present, requirements are put forward on the broadband characteristics and the tunability of a mode converter, and therefore the fiber type tunable broadband mode converter has wide application prospects in the fields of fiber communication and fiber sensing.
The patents relating to broadband mode converters at home and abroad are as follows: a broadband optical fiber mode converter (Chinese patent CN 203838366U), an optical fiber type broadband optical vortex filter (Chinese patent CN 108089267B), a tunable large-bandwidth nano optical fiber band-pass filter (Chinese patent CN 109655974A), an optical fiber type ultra-wideband band-stop filter (Chinese patent CN 110716265A); there have been some papers and patents both at home and abroad discussing the design and fabrication of fiber-optic type mode converters. Although the mode converter based on the traditional fiber grating can realize tunability through the transformation of the grating period, the bandwidth is usually narrow, generally only one to twenty nanometers exists, and the mode converter cannot cover the whole communication waveband; wide bandwidth can be achieved by using the double-tuning characteristic of the dispersion transition point of the optical fiber, but the dispersion transition point is the inherent characteristic of the optical fiber, and it is difficult to achieve tunability (https:// doi.org/10.1364/oe.389471), and if a wider broadband is to be achieved, the center of the converted spectrum is not flat enough, i.e. the conversion efficiency of the band center is not high. The broadband mode conversion can be realized by using a specially designed optical fiber or coupler, for example, the three-core optical fiber in the patent "a broadband mode converter (chinese patent CN 203838366U)" can realize the conversion between the fundamental mode and the high-order mode, but this method requires a complicated process and has poor compatibility with the existing optical fiber devices and optical fiber networks. In summary, the conventional optical fiber mode converter does not have both tunable broadband and flat conversion characteristics, and has poor compatibility with the conventional optical fiber network and requirements on the manufacturing process.
Disclosure of Invention
The purpose of the invention is as follows: aiming at the problems in the prior art, the invention provides an optical fiber type tunable broadband mode converter with high compatibility and smooth conversion and a preparation method thereof.
The technical scheme is as follows: the invention relates to an optical fiber type tunable broadband mode converter, in particular to a mode converter which is uniformly thinned to a preset fiber core radius R n The long-period fiber grating with the preset non-uniform period characteristic is manufactured by the few-mode fiber.
Further, the preset core radius R n The method specifically comprises the following steps:
R n ＝R 0 -(λ m -λ 0 )/c
in the formula, λ 0 And λ m Respectively, the wavelength of the dispersion conversion point of the few-mode optical fiber before being attenuated and the central wavelength, R, required to be reached by the designed converter 0 Is half of a few-mode optical fiber before being drawnAnd c is a characteristic parameter related to the few-mode optical fiber, and the value of c is greater than 0.
Further, the preset non-uniform period specifically includes:
Λ j ＝Λ 0 (1-ΔΦ j /2π)
ΔΦ j ＝Φ j -Φ j-1
Φ j ＝A×cos(B×2π×(j-1)×Λ 0 /L)
in the formula, Λ j Represents the period length of the j-th period, j is more than or equal to 1 and less than or equal to N, N is the number of periods, and Λ 0 Is a reference period length, Δ Φ j Representing the phase change of the j-th cycle, phi j The phase of j period is shown, L is the length of the fiber grating, z is the coordinate of the longitudinal axis direction of the fiber grating, and A, B is the optimized parameter value.
Further, the few-mode optical fiber is any one of a two-mode optical fiber, a four-mode optical fiber, a six-mode optical fiber or a nine-mode optical fiber.
Further, the few-mode optical fiber is uniformly drawn and thinned by heating to a molten state through an oxyhydrogen flame or a carbon dioxide laser.
Furthermore, the long-period fiber grating with the preset non-uniform period characteristic is manufactured by any one of manufacturing methods of ultraviolet, mechanical, electric arc, carbon dioxide laser or heating spiral torsion.
The invention provides a preparation method of an optical fiber type tunable broadband mode converter, which comprises the following steps:
fixing the few-mode optical fiber;
uniformly thinning the few-mode optical fiber to a preset fiber core radius R n ；
And manufacturing a long-period fiber grating with preset non-uniform period characteristics on the uniformly-thinned few-mode fiber.
Further, the few-mode optical fiber is uniformly drawn and thinned by heating to a molten state through an oxyhydrogen flame or a carbon dioxide laser.
Furthermore, the long-period fiber grating with the preset non-uniform period characteristic is manufactured by any one of manufacturing methods of ultraviolet, mechanical, electric arc, carbon dioxide laser or heating spiral torsion.
The invention provides another preparation method of an optical fiber type tunable broadband mode converter, which comprises the following steps:
Fixing the few-mode optical fiber between a clamp and the center of a rotator, wherein the clamp is positioned on a translation table 1, the rotator is positioned on a translation table 2, and the translation table 1 and the translation table 2 are both positioned on a translation table 3;
sleeving a sapphire tube outside the few-mode optical fiber and fixing;
an optical switch of the carbon dioxide laser is turned on, the emitted laser reaches the sapphire tube through the reflector, so that the few-mode optical fiber is uniformly heated to a molten state, the translation platform 1 and the translation platform 2 are reversely moved, and the few-mode optical fiber is gradually uniformly thinned to a preset fiber core radius R n ；
And after the uniformly thinned few-mode optical fiber is reheated to a molten state, the movement of the thinned few-mode optical fiber and the rotation of the rotator are simultaneously controlled, and the long-period fiber grating with the non-uniform period of spiral refractive index change is formed by controlling different proportional relations of the movement speed and the rotation speed.
Has the beneficial effects that: compared with the prior art, the invention has the following remarkable advantages: the invention adopts few-mode optical fibers supporting more optical fiber modes, can effectively support a plurality of optical fiber modes required in mode division multiplexing, greatly improves the transmission capacity of optical fiber communication, can realize mode conversion with bandwidth of hundreds of nanometers by utilizing the double resonance characteristic of optical fiber dispersion conversion points, adopts phase sampling gratings to realize the flat conversion characteristic of the whole conversion waveband, and realizes the tunable central wavelength of the mode converter within a certain range through the uniform attenuation of the radius of the optical fibers, namely, can support the mode conversion of the optical fiber communication waveband. The manufacturing method is simple, and only needs the common manufacturing processes of fusion attenuation and long-period grating in the traditional manufacturing process of the optical fiber device.
Drawings
FIG. 1 is a block diagram of a fiber-type tunable wideband mode converter provided by the present invention;
FIG. 2 is a schematic diagram of a method for fabricating an optical fiber type tunable wideband mode converter according to the present invention;
FIG. 3 is a graph of the mode effective index for few-mode fibers selected for cases 1-4;
FIG. 4 is a graph of fiber radius and LP for the reduced-mode fiber of cases 1 and 2 after attenuation 01 、LP 21 A graph of mode-converted dispersion transition points;
FIG. 5 is the fiber radius and LP for the reduced mode fiber of cases 3 and 4 after attenuation 11 、LP 21 A graph of mode-converted dispersion transition points;
FIG. 6 shows LP for the few-mode fiber after attenuation in cases 1 and 2 01 、LP 21 A graph of the dispersion transition point of mode transition as a function of fiber radius;
FIG. 7 is the LP for the few-mode fiber after attenuation in cases 3 and 4 11 、LP 21 A graph of the dispersion transition point of mode transition as a function of fiber radius;
FIG. 8 shows LP for the wideband mode converter in case 1 01 、LP 21 Mode conversion spectrogram of mode in band 1(1760nm-1889 nm);
FIG. 9 shows LP for the wideband mode converter in case 2 01 、LP 21 Mode conversion spectrum of mode at band 2(1535nm-1654 nm);
FIG. 10 shows LP for the wideband mode converter in case 3 11 、LP 21 Mode conversion spectrogram of mode in band 3(1663nm-1800 nm);
FIG. 11 shows LP for the wideband mode converter in case 4 11 、LP 21 Mode conversion spectrum of mode at band 4(1475nm-1610 nm).
Detailed Description
The present embodiment provides an optical fiber type tunable broadband mode converter, which is specifically a fiber type tunable broadband mode converter that is uniformly thinned to a predetermined core radius R n The structure of the long-period fiber grating with the preset non-uniform period characteristic manufactured by the few-mode fiber is shown as figure 1, wherein a light gray part is a cladding, a middle gray part is a fiber core, and a deep gray part is formedA non-uniform periodic index change portion. The few-mode fiber may be a few-mode fiber such as a two-mode fiber, a four-mode fiber, a six-mode fiber, or a nine-mode fiber, and is not limited to the above example fibers. The uniform attenuation of the few-mode optical fiber is realized by uniformly elongating after heating to a molten state, the central wavelength adjustment of the optical fiber dispersion conversion point can be realized by uniformly attenuating the few-mode optical fiber, the central wavelength tuning of the mode converter is realized, and the radius R of a fiber core is preset n Determined by the center wavelength (dispersion transition point of the attenuated fiber) that the broadband mode converter needs to reach, expressed as: r n ＝R 0 -(λ m -λ 0 ) C, in the formula, lambda 0 And λ m Respectively, the wavelength of the dispersion conversion point of the few-mode optical fiber before being attenuated and the central wavelength, R, required to be reached by the designed converter 0 C is a characteristic parameter related to the few-mode optical fiber, and the value of c is larger than 0. In order to ensure the flatness of a converted frequency spectrum, a phase sampling grating principle is introduced, namely a long-period fiber grating with a non-uniform period is manufactured, wherein the long-period fiber grating with the non-uniform period is manufactured by any one of ultraviolet, mechanical, electric arc, carbon dioxide laser or heating spiral torsion. The manufactured non-uniform period specifically comprises the following steps: lambda j ＝Λ 0 (1-ΔΦ j /2π)，ΔΦ j ＝Φ j -Φ j-1 ，Φ j ＝A×cos(B×2π×(j-1)×Λ 0 L), in the formula, Λ j Represents the period length of the j-th period, j is more than or equal to 1 and less than or equal to N, N is the number of periods, and Λ 0 Is a reference period length, Δ Φ j Represents the phase change of the j-th cycle, denoted as Δ Φ j ＝Φ j -Φ j-1 Wherein phi j The phase of j period is shown, L is the length of the fiber grating, z is the coordinate of the longitudinal axis direction of the fiber grating, and A, B is the optimized parameter value.
According to the coupled mode theory, the resonant wavelength of the grating meets the phase matching condition: lambda [ alpha ] pq ＝Λ pq |n p -n q L, where n p And n q Effective refractive indices, Λ, of the p-th and q-th fiber modes, respectively pq Is thatThe grating period, | | is the absolute value sign, λ pq Is the resonant wavelength of the corresponding long period grating. By using the dual resonance characteristic of the dispersion transition point, when the resonance wavelength is lambda pq At a central wavelength λ m The double resonance characteristic occurs when nearby, i.e. at two approximations of lambda m Around the central wavelength, two wavelengths satisfy the phase matching condition, namely: lambda [ alpha ] pq,1-2 ＝Λ pq |n p -n q L, two wavelengths λ in which resonance occurs pq,1 And λ pq,2 Approximately satisfies lambda pq,1 +λ pq,2 ＝2λ m . The bandwidth of the mode converter can be greatly expanded by utilizing the double resonance characteristic of the dispersion conversion point, so that the mode converter with the bandwidth of hundreds of nanometers is obtained, and the obtained bandwidth of the mode converter depends on two resonant wavelengths lambda pq,1 And λ pq,2 The difference between them. It should be noted that, in the operating broadband range, it is ensured that the type of mode of the optical fiber is not changed. Bandwidth W of fiber-type tunable broadband mode converter is determined by period length Λ of prescribed non-uniform period of long-period fiber grating 0 It is determined that the conversion efficiency γ is determined by the refractive index modulation depth Δ n of the long period fiber grating.
The embodiment provides a preparation method of an optical fiber type tunable broadband mode converter, which comprises the following steps:
(1) fixing the few-mode optical fiber;
(2) uniformly thinning the few-mode optical fiber to a preset fiber core radius R n (ii) a Wherein, the uniform attenuation is realized by uniform elongation after heating to a molten state by oxyhydrogen flame or a carbon dioxide laser;
(3) And manufacturing a long-period fiber grating with a preset non-uniform period characteristic on the uniformly-thinned few-mode fiber, specifically manufacturing the long-period fiber grating by any one of ultraviolet, mechanical, electric arc, carbon dioxide laser or heating spiral torsion.
The present embodiment further provides another method for manufacturing the above optical fiber type tunable wideband mode converter, as shown in fig. 2, the method includes the following steps:
(1) fixing the few-mode optical fiber between a clamp and the center of a rotator, wherein the clamp is positioned on a translation table 1, the rotator is positioned on a translation table 2, and the translation table 1 and the translation table 2 are both positioned on a translation table 3;
(2) sleeving a Sapphire tube (Sapphire tube) outside the few-mode optical fiber and fixing;
(3) opening of CO 2 The laser emitted by an optical switch of the laser reaches a sapphire tube through a reflector, so that the few-mode optical fiber is uniformly heated to a molten state, and the translation platform 1 and the translation platform 2 are reversely moved, so that the few-mode optical fiber is gradually uniformly thinned to a preset fiber core radius R n ；
(4) And after the uniformly thinned optical fiber is reheated to a molten state, the movement of the thinned optical fiber and the rotation of the rotator are simultaneously controlled, and the long-period optical fiber grating with the non-uniform period of the spiral refractive index change is formed by controlling different proportional relations of the movement speed and the rotation speed.
In the above method, the heating, moving and rotating of the attenuated optical fiber are synchronously controlled to manufacture the spiral long-period fiber grating. The original optical fiber heated to a molten state is synchronously moved and rotated to form the spiral fiber grating with a specific design change period, the length lambda of the formed specific design spiral period is determined by the moving speed v (mm/s-millimeter/second) and the rotating speed w (turn/s-turn/second) of the original optical fiber, and is expressed as lambda which is v/w (mm/turn-millimeter/turn), and the ratio of the moving speed to the rotating speed is controlled in the manufacturing process, so that the non-uniform period can be realized. Due to the torsional tangential force when heated, a spiral periodic length structure with specific design is formed in the cooled spiral optical fiber, and the spiral optical fiber has the characteristic of spiral refractive index distribution.
The following experiment was carried out using this example, specifically using four cases, all of which used the same four-mode fiber (long-flier step-index four-mode fiber), the fiber core and cladding radii of 9.5um and 62.5um, respectively, and the core and cladding refractive indices of 1.4499 and 1.444, respectively, which supported LP 01 (HE 11 ) And LP 21 (HE 21 /TE 01 /TM 01 ) The mode effective refractive indices of the mode groups are shown in FIG. 3, where the results are given by finite element method And calculating the result. The detailed experimental parameters for each case were specifically: in case 1, the core radius of the four-mode fiber after being attenuated is 8.74um, the refractive index is 1.4499, the cladding radius is 57.5um, and the refractive index is 1.444, the reference period length of the helical long-period fiber grating is 418.5um, the period number of the grating is 20, and the refractive index modulation depth is 9.5 × 10 -5 Using a phase sampling function of phi j ＝0.35×cos(2×2π×(j-1)×Λ 0 /L), the conversion mode is LP 01 、LP 21 A mode; in case 2, the core radius of the four-mode fiber after being attenuated is 7.64um, the refractive index is 1.4499, the cladding radius is 50.26um, the refractive index is 1.444, the reference period length of the spiral long-period fiber grating is 366um, the period number of the grating is 20, and the refractive index modulation depth is 1.35 × 10 -4 Phase sampling function phi j ＝0.77×cos(1.93×2π×(j-1)×Λ 0 /L), the conversion mode is LP 01 、LP 21 A mode; in case 3, the core radius of the four-mode fiber after being attenuated is 8.74um, the refractive index is 1.4499, the cladding radius is 57.5um, and the refractive index is 1.444, the reference period length of the helical long-period fiber grating is 772.5um, the period number of the grating is 20, and the refractive index modulation depth is 6.4 × 10 -5 The selected phase sampling function is phi j ＝0.8×cos(1.86×2π×(j-1)×Λ 0 /L), the conversion mode is LP 11 、LP 21 A mode; the parameters of the four-mode fiber after attenuation in case 4 are: fiber core radius 7.79um, refractive index are 1.4499, and the cladding radius is 51.25um, and the refractive index is 1.444, spiral long period fiber grating's benchmark period length be 688um, the cycle number of grating is 20, the refractive index modulation depth is 6.5 x 10 -5 Phase sampling function phi j ＝0.61×cos(1.92×2π×(j-1)×Λ 0 /L), the conversion mode is LP 11 、LP 21 Mode(s).
FIG. 4 is a graph of the radius of the fiber after attenuation and LP for cases 1-2 01 、LP 21 A graph of mode-converted dispersion transition points; FIG. 5 shows the radius and LP of the fiber after attenuation in case 3-4 11 、LP 21 A graph of mode-converted dispersion transition points; FIG. 6 shows LP in cases 1-2 01 、LP 21 A graph of the dispersion transition point of mode transition as a function of fiber radius; FIG. 7 shows LP in cases 3-4 11 、LP 21 The graph of the dispersion transition point of the mode transition as a function of the fiber radius, as can be seen in fig. 4-7, the dispersion transition point can be uniformly adjusted by uniform attenuation of the fiber.
FIG. 8 shows LP in case 1 01 、LP 21 Mode conversion spectrum of mode at band 1(1760nm-1889nm), shown as LP 01 Switching to LP 21 Transmission spectrum (LP) 01 Loss spectrum of the pattern, embodying LP 01 Mode-engineered tunable broadband mode-post-converter state) and cross-spectrum (LP) 21 Conversion spectrum of modes embodying LP 21 Mode post-design tunable wideband mode converter state), it can be seen that the broadband range of 20dB conversion efficiency (99% conversion efficiency) is from 1760nm to 1889nm, with a width of 129 nm. FIG. 9 shows LP in case 2 01 、LP 21 Mode-converted spectra of modes in band 2(1535nm-1654nm), showing LP 01 、LP 21 The broadband range of 20dB conversion efficiency from 1535nm to 1654nm and the width of the transmission spectrum and the cross spectrum of the mode conversion are shown in the figure. FIG. 10 shows LP in case 3 11 、LP 21 Mode conversion spectrum of mode at band 3(1663nm-1800nm), LP is shown in the figure 11 、LP 21 The transmission spectrum and the cross spectrum of the mode conversion show that the broadband range of 20dB conversion efficiency is 1663nm to 1800nm, and the width is 137 nm. FIG. 11 shows LP in case 4 11 、LP 21 Mode-converted spectrograms of the modes in the band 4(1475nm-1610nm), shown as LP 11 、LP 21 The transmission spectrum and the cross spectrum of the mode conversion show that the broadband range of 20dB conversion efficiency is from 1475nm to 1610nm, and the width is 135 nm.
While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
Claims (8)
1. Optical fiber type is adjustableA harmonic broadband mode converter, characterized by: the converter is characterized in that the converter is uniformly thinned to a preset fiber core radius R n The long-period fiber grating which is made of the few-mode fiber and has the preset non-uniform period characteristic;
the preset fiber core radius R n The method specifically comprises the following steps:
R n ＝R 0 -(λ m -λ 0 )/c
in the formula, λ 0 And λ m Respectively, the wavelength of the dispersion conversion point of the few-mode optical fiber before being attenuated and the central wavelength, R, required to be reached by the designed converter 0 C is the radius of the few-mode optical fiber before thinning, is a characteristic parameter related to the few-mode optical fiber, and the value of c is more than 0;
the preset non-uniform period specifically comprises the following steps:
Λ j ＝Λ 0 (1-ΔΦ j /2π)
ΔΦ j ＝Φ j -Φ j-1
Φ j ＝A×cos(B×2π×(j-1)×Λ 0 /L)
in the formula, Λ j Represents the period length of the j-th period, j is more than or equal to 1 and less than or equal to N, N is the number of periods, and Λ 0 Is a reference period length, Δ Φ j Representing the phase change of the j-th cycle, phi j The phase of the j-th period is shown, L is the fiber grating length, and A, B is the optimized parameter value.
2. The fiber-optic tunable wideband mode converter of claim 1, wherein: the few-mode optical fiber is any one of a two-mode optical fiber, a four-mode optical fiber, a six-mode optical fiber or a nine-mode optical fiber.
3. The fiber-optic tunable wideband mode converter of claim 1, wherein: the few-mode optical fiber is uniformly thinned by heating to a molten state through oxyhydrogen flame or a carbon dioxide laser and then uniformly stretching.
4. The fiber-optic tunable wideband mode converter of claim 1, wherein: the long-period fiber grating with the preset non-uniform period characteristic is manufactured by any one of manufacturing modes of ultraviolet, machinery, electric arc, a carbon dioxide laser and heating spiral torsion.
5. A method for making the fiber-optic tunable wideband mode converter of claim 1, wherein: the method comprises the following steps:
fixing the few-mode optical fiber;
uniformly thinning the few-mode optical fiber to a preset fiber core radius R n ；
And manufacturing a long-period fiber grating with preset non-uniform period characteristics on the uniformly-thinned few-mode fiber.
6. The method of claim 5, wherein the method comprises: the few-mode optical fiber is uniformly thinned by heating to a molten state through oxyhydrogen flame or a carbon dioxide laser and then uniformly stretching.
7. The method of claim 5, wherein the method comprises: the long-period fiber grating with the preset non-uniform period characteristic is manufactured by any one of manufacturing modes of ultraviolet, machinery, electric arc, a carbon dioxide laser and heating spiral torsion.
8. A method for making the fiber-optic tunable wideband mode converter of claim 1, wherein: the method comprises the following steps:
fixing the few-mode optical fiber between a clamp and the center of a rotator, wherein the clamp is positioned on a translation table 1, the rotator is positioned on a translation table 2, and the translation table 1 and the translation table 2 are both positioned on a translation table 3;
Sleeving a sapphire tube outside the few-mode optical fiber and fixing;
the optical switch of the carbon dioxide laser is turned on, and the emitted laser passes through the reflector toReaching the sapphire tube to uniformly heat the few-mode fiber to a molten state, and reversely moving the translation stage 1 and the translation stage 2 to gradually and uniformly thin the few-mode fiber to a preset fiber core radius R n ；
And after the uniformly thinned few-mode optical fiber is reheated to a molten state, the movement of the thinned few-mode optical fiber and the rotation of the rotator are simultaneously controlled, and the long-period fiber grating with the non-uniform period of spiral refractive index change is formed by controlling different proportional relations of the movement speed and the rotation speed.
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| CN105022117A (en) * | 2015-07-23 | 2015-11-04 | 江苏大学 | Double-core fiber based long-period FBG mode-field converter |
| CN109581590A (en) * | 2018-09-03 | 2019-04-05 | 暨南大学 | A kind of LP01 mode-LPmn mode full fiber type mode converter |
| CN109655974A (en) * | 2019-01-22 | 2019-04-19 | 山西大学 | A kind of tunable big bandwidth nano optical fibers bandpass filter |
| CN111856647A (en) * | 2020-08-20 | 2020-10-30 | 中国人民解放军国防科技大学 | Few-mode fiber Bragg grating capable of inhibiting high-order mode reflection and laser system |
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| US6768835B2 (en) * | 2002-09-04 | 2004-07-27 | Fitel Usa Corp | Tunable mode-converters using few mode fibers |
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|---|---|---|---|---|
| CN105022117A (en) * | 2015-07-23 | 2015-11-04 | 江苏大学 | Double-core fiber based long-period FBG mode-field converter |
| CN109581590A (en) * | 2018-09-03 | 2019-04-05 | 暨南大学 | A kind of LP01 mode-LPmn mode full fiber type mode converter |
| CN109655974A (en) * | 2019-01-22 | 2019-04-19 | 山西大学 | A kind of tunable big bandwidth nano optical fibers bandpass filter |
| CN111856647A (en) * | 2020-08-20 | 2020-10-30 | 中国人民解放军国防科技大学 | Few-mode fiber Bragg grating capable of inhibiting high-order mode reflection and laser system |
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