CN112230328B - Ultrashort double-core photonic crystal fiber polarization beam splitter based on gold filling - Google Patents
Ultrashort double-core photonic crystal fiber polarization beam splitter based on gold filling Download PDFInfo
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- 239000000835 fiber Substances 0.000 title claims abstract description 78
- 230000010287 polarization Effects 0.000 title claims abstract description 37
- 239000004038 photonic crystal Substances 0.000 title claims abstract description 31
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 title claims abstract description 23
- 239000010931 gold Substances 0.000 title claims abstract description 23
- 229910052737 gold Inorganic materials 0.000 title claims abstract description 23
- 238000005253 cladding Methods 0.000 claims abstract description 15
- 239000013307 optical fiber Substances 0.000 claims abstract description 15
- 239000002184 metal Substances 0.000 claims abstract description 5
- 229910052751 metal Inorganic materials 0.000 claims abstract description 5
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 6
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- 238000002198 surface plasmon resonance spectroscopy Methods 0.000 description 2
- 241001347978 Major minor Species 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
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- SYHGEUNFJIGTRX-UHFFFAOYSA-N methylenedioxypyrovalerone Chemical compound C=1C=C2OCOC2=CC=1C(=O)C(CCC)N1CCCC1 SYHGEUNFJIGTRX-UHFFFAOYSA-N 0.000 description 1
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- G02B6/02—Optical fibres with cladding with or without a coating
- G02B6/02042—Multicore optical fibres
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- G—PHYSICS
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- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/02—Optical fibres with cladding with or without a coating
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- G02B6/023—Microstructured optical fibre having different index layers arranged around the core for guiding light by reflection, i.e. 1D crystal, e.g. omniguide
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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 an ultrashort double-core photonic crystal fiber polarization beam splitter based on gold filling, which comprises: a core region and a cladding region; the core region comprises a first elliptical hole, two second elliptical holes and two third elliptical holes; the first elliptical hole is located in the center of the core region; the two second elliptical holes are respectively arranged on the upper side and the lower side of the first elliptical hole in the vertical direction, and metal gold is filled in the two second elliptical holes; the left side and the right side of the first elliptical hole in the horizontal direction are respectively provided with a first fiber core and a second fiber core of the optical fiber; the two third elliptical holes are respectively arranged on the left side and the right side of the first fiber core and the second fiber core in the horizontal direction; the cladding region is positioned on the outer layer of the core region and comprises a plurality of uniformly arranged first round air holes and second round air holes; the beam splitter introduces the surface plasma resonance effect based on gold filling, and has better transmission effect and shorter device length compared with the full air hole type photonic crystal fiber.
Description
Technical Field
The invention relates to the field of photonic crystal fiber beam splitters, in particular to an ultrashort double-core photonic crystal fiber polarization beam splitter based on gold filling.
Background
The prominent characteristic of the photonic crystal fiber is gradually excavated along with the attention of people, the prominent characteristic of the photonic crystal is the urgent need of optical communication devices, the polarization beam splitter is an important one of the optical communication devices, and the effect of the photonic crystal fiber on the polarization beam splitter is reflected in front of people. And the photonic crystal fiber has the characteristics of flexible structure and novelty, so the photonic crystal fiber polarization beam splitter has the advantages that the traditional beam splitter does not have. Polarization beam splitters have the function of splitting a beam of light having two polarization states, and are therefore widely used in optical communication systems as important optical components. At present, people mainly adopt the following schemes when designing the beam splitter:
(1) most of the early polarizing beam splitters were fabricated from conventional dual core optical fibers based on the principle of birefringence. However, the traditional optical fiber is often small in birefringence, so that the prepared beam splitter is generally large in size, low in extinction ratio, narrow in bandwidth and single in structural design, and the integration and transmission capacity of an optical communication system are limited. In addition, the polarization beam splitter based on the traditional optical fiber has the wavelength dependence characteristic and the working waveband is single, which greatly limits the application range of the polarization beam splitter.
(2) Based on the all-air hole type photonic crystal fiber. The single polarization output wavelength beam splitter designed by the scheme is usually formed by constructing a structure birefringent structure in a core region and a cladding region of a traditional photonic crystal fiber on the basis of the traditional photonic crystal fiber, and the light guide mechanism of the single polarization output wavelength beam splitter is also the same as that of the traditional photonic crystal fiber. Moreover, the fiber core of the beam splitter is formed by air hole deletion like the traditional photonic crystal fiber, and the fiber core is not regular circular because the core region is used for constructing a birefringent structure. However, because of low birefringence, the length of the optical fiber is often very long, and the requirement of device miniaturization cannot be met.
Disclosure of Invention
In view of the above technical problems, an object of the present invention is to provide a polarization beam splitter based on gold-filled ultrashort dual-core photonic crystal fiber for splitting light with 1550nm wavelength, so as to solve the above mentioned technical problems, and the following steps are specifically performed:
a golden-filled ultrashort dual-core photonic crystal fiber polarization beam splitter comprises: a core region and a cladding region filled with a pure quartz glass base material;
the core region comprises a first elliptical hole, two second elliptical holes and two third elliptical holes; wherein the first elliptical hole is located in the center of the core region, the minor axis diameter of the first elliptical hole is dx1, the major axis diameter is dy1, and air is in the first elliptical hole; the two second elliptical holes are respectively arranged on the upper side and the lower side of the first elliptical hole in the vertical direction, the vertical distance from the two second elliptical holes to the first elliptical hole is lambada 2, the diameter of the long axis of each second elliptical hole is dx2, the diameter of the short axis of each second elliptical hole is dy2, and metal gold is filled in the two second elliptical holes; the left side and the right side of the first elliptical hole in the horizontal direction are respectively provided with a first fiber core and a second fiber core of the optical fiber, and the horizontal distance between the center of the first fiber core and the center of the second fiber core and the first elliptical hole is lambada 1; the two third elliptical holes are respectively arranged on the left side and the right side of the first fiber core and the second fiber core in the horizontal direction, the horizontal distance between the two third elliptical holes and the centers of the first fiber core and the second fiber core is Lambda 1, the minor axis diameter of each third elliptical hole is dx3, the major axis diameter is dy3, and air is filled in each third elliptical hole; wherein dx1 ═ dy2< dx3, dy1 ═ dx2< dy 3;
the cladding region is positioned on the outer layer of the core region and comprises a plurality of uniformly arranged first round air holes and second round air holes; the first air round holes are uniformly distributed on the upper side and the lower side of the first elliptical hole, the first air round holes are arranged in an upper regular trapezoid structure and a lower regular trapezoid structure, the diameter of each first air round hole is d, the hole spacing is inverted V1, and the hole spacing between the third elliptical hole and the first air round holes adjacent to the upper side and the lower side in the vertical direction is inverted V2; the second air round holes are uniformly distributed on the outer sides of the two third elliptical holes, the diameters of the second air round holes are d, the hole intervals are Λ 1, and the hole intervals between the second air round holes and the first air round holes adjacent to the upper side and the lower side of the vertical direction are Λ 2; where d ═ dx3, Λ 1< Λ 2.
Optionally, the minor axis diameter dx1 of the first elliptical hole ranges from 0.45 μm to 0.55 μm.
Optionally, the major axis diameter dy1 of the first elliptical hole ranges from 0.95 μm to 1.05 μm.
Optionally, the major axis diameter dx2 of the second elliptical hole ranges from 0.95 μm to 1.05 μm.
Optionally, the minor axis diameter dy2 of the second elliptical hole ranges from 0.45 μm to 0.55 μm.
Optionally, the minor axis diameter dx3 of the third elliptical hole ranges from 0.95 μm to 1.05 μm.
Optionally, the major axis diameter dy3 of the third elliptical hole ranges from 1.55 μm to 1.65 μm.
Optionally, the diameter d of the first air round hole and the second air round hole ranges from 0.95 μm to 1.05 μm.
Optionally, the value range of the distance Λ 1 between the first air circular holes is 1.109-1.111 μm.
Optionally, the value range of Λ 2 is 1.45-1.55 μm.
Compared with the prior art, the invention has the following technical effects:
(1) the beam splitter introduces SPR effect, is shorter than a full air hole type photonic crystal fiber, and has better light splitting effect. The length of the optical fiber of the beam splitter is only 62.5 mu m, and the extinction ratio at the wavelength of 1550nm can reach-76 dB.
(2) The beam splitter has wider communication wave band and can realize single polarization output within the wavelength range of 1.50-1.61 mu m.
(3) The invention overcomes the defects of large volume, low extinction ratio, narrow bandwidth and the like of the traditional polarization beam splitter, and meets the requirements of a future full optical network with super-large capacity and easy integration.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings 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 other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a cross-sectional view of a gold-filled ultrashort dual-core photonic crystal fiber polarization beam splitter of the present invention.
FIG. 2 is a graph showing the refractive index of each polarization mode of the ultra-short dual-core photonic crystal fiber polarization beam splitter based on gold filling varying with wavelength.
FIG. 3 is a graph showing the variation of the coupling length ratio with wavelength of an ultrashort double-core photonic crystal fiber polarization beam splitter based on gold filling.
FIG. 4 is a normalized energy versus beam splitter length for a gold-filled ultrashort dual-core photonic crystal fiber polarization beam splitter of the present invention.
FIG. 5 is a graph of extinction ratio of a polarization beam splitter of ultra-short dual-core photonic crystal fiber based on gold filling as a function of wavelength.
In the figure, 1 is the central elliptical air hole, A, B is the two cores of the fiber, 2 is the gold-filled elliptical air hole, 3 is the two elliptical air holes next to the horizontal core, 4 is the cladding region air hole, and 5 is the pure silica glass substrate.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the present invention will be described in further detail with reference to the accompanying drawings, and it is apparent that the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As shown in fig. 1, a cross-sectional view of a gold-filled ultrashort dual-core photonic crystal fiber polarization beam splitter of the present invention includes: a core region and a cladding region filled with a pure quartz glass base material 5;
the core region comprises a first elliptical hole 1, two second elliptical holes 2 and two third elliptical holes 3; wherein the first elliptical hole 1 is located in the center of the core area, the minor axis diameter of the first elliptical hole 1 is dx1, the major axis diameter is dy1, and air is filled in the first elliptical hole; the two second elliptical holes 2 are respectively arranged on the upper side and the lower side of the first elliptical hole 1 in the vertical direction, the vertical distance from the first elliptical hole 1 is Λ 2, the diameter of the long axis of each second elliptical hole 2 is dx2, the diameter of the short axis of each second elliptical hole 2 is dy2, and metal gold is filled in the two second elliptical holes 2; the left side and the right side of the first elliptical hole 1 in the horizontal direction are respectively provided with a first fiber core A and a second fiber core B of the optical fiber, and the horizontal distance between the center of the first fiber core A and the center of the second fiber core B and the first elliptical hole 1 is lambda 1; the two third elliptical holes 3 are respectively arranged on the left side and the right side of the first fiber core A and the second fiber core B in the horizontal direction, the horizontal distance between the two third elliptical holes 3 and the centers of the first fiber core A and the second fiber core B is Λ 1, the minor axis diameter of each third elliptical hole 3 is dx3, the major axis diameter is dy3, and air is filled in each third elliptical hole 3; wherein dx1 ═ dy2< dx3, dy1 ═ dx2< dy 3;
the cladding region is positioned at the outer layer of the core region and comprises a plurality of uniformly arranged first round air holes 4 and second round air holes 6; the first air round holes 4 are uniformly distributed on the upper side and the lower side of the first elliptical hole 1, the first air round holes 4 are distributed into an upper regular trapezoid structure and a lower regular trapezoid structure, the distribution number is 5, 6, 7, 8 or 8, the diameters of the first air round holes 4 are d, the hole intervals are inverted V1, and the hole intervals between the third elliptical hole 3 and the first air round holes 4 adjacent to the upper side and the lower side in the vertical direction are inverted V2; the second air round holes 6 are uniformly distributed on the outer sides of the two third elliptical holes 3, the diameters of the second air round holes 6 are d, the hole intervals are Λ 1, and the hole intervals between the second air round holes 6 and the first air round holes 4 adjacent to the upper side and the lower side in the vertical direction are Λ 2; where d ═ dx3, Λ 1< Λ 2. As shown in fig. 1, the second air circular holes 6 are two outside the third elliptical hole 3. The diameter difference, the major-minor axis difference and the distance difference of the hole spacing of each air hole in the structure enable the core area structure to have excellent double refraction effect and surface plasma effect, so that optical signal transmission is facilitated, noise is reduced, and transmission efficiency is improved.
Optionally, the minor axis diameter dx1 of the first elliptical hole 1 ranges from 0.45 to 0.55 μm, and the major axis diameter dy1 ranges from 0.95 to 1.05 μm. The first elliptical hole 1 having the above size range forms two light guiding core paths a and B that can be used to confine and transmit light. It is through these two paths that the polarization beam splitter separates the light waves of two orthogonal polarization states. Longitudinal coupling and transverse coupling between the elliptical hole double cores generate difference, and birefringence effect is increased.
Optionally, the minor axis diameter dy2 of the second elliptical hole 2 ranges from 0.45 μm to 0.55 μm. The value range of the major axis diameter dx2 of the second elliptical hole 2 is 0.95-1.05 μm. When light is emitted into the optical fiber, the upper and lower double gold holes respectively generate respective surface plasma modes, and according to a coupling mode theory, a mode coupling effect is generated between the respective surface plasma modes, so that a surface plasma supermode is formed. And because the gold hole is oval, and has the dimensional relationship that the value range of the minor axis diameter dy1 is 0.45-0.55 μm, and the value range of the major axis diameter dx1 is 0.95-1.05 μm, the formed surface plasma supermode has high birefringence.
Optionally, the minor axis diameter dx3 of the third air elliptical hole 3 ranges from 0.95 μm to 1.05 μm. The major axis diameter dy3 of the third air elliptical hole 3 ranges from 1.55 to 1.65 μm. The size range of the third air elliptical hole 3 can enable the fiber core to generate high birefringence, and the first air elliptical hole 1 and the second air elliptical hole 2 in the size range are matched, so that a large adjusting effect can be achieved on the effective refractive index of the photonic crystal fiber.
Optionally, the diameter d of the first air circular hole 4 is 0.95-1.05 μm. The round hole of this size is convenient for form in the aspect of the preparation to convenient formation a plurality of arrangement structure that have certain shape improve the shaping efficiency of product, can improve the birefringence effect with the elliptical aperture cooperation in fibre core region simultaneously.
Optionally, the distance Λ 1 between the first air circular holes 4 ranges from 1.109 μm to 1.111 μm. Facilitates the formation of uniformly distributed porous structures and reduces optical loss.
Optionally, the value range of the pitch Λ 2 between the second air round hole 6 and the first air round hole 4 adjacent to the upper side and the lower side in the vertical direction is 1.45-1.55 μm. The second air round hole 6 is matched with the third elliptical hole 3, so that light is guaranteed to be concentrated in the fiber core area for transmission, light loss is reduced, and light transmission efficiency is improved.
The filling material between the fiber core region and the cladding region is a pure quartz glass substrate material, so that the product manufacturing yield is improved, and the optical transmission efficiency is improved.
As shown in fig. 1, 1 is a central elliptical air hole; A. b is 2 fiber cores of the optical fiber, and 2 is 2 gold elliptical holes at two sides of the central air hole in the vertical direction; 3 are 2 air holes at two sides of the central air hole in the horizontal direction; 4 and 6 are cladding air holes; 5 is a pure quartz glass substrate. The 2 fiber cores are silicon-based substrates surrounded by air holes, the fiber cores are regular rectangles, and the cladding is regular upper and lower trapezoids. In addition, the introduction of air holes of different sizes around the core is also utilized to increase the structural birefringence of the core region. Thus, the birefringence of the present invention can be viewed as a combination of surface plasmon resonance effects and artificially structured core region structure birefringence. According to the coupled mode theory, the mode coupling effect can occur between 2 fiber cores of the double-core structure, and 4 supermodes are formed in a conformal mode.
According to the fiber mode resonance coupling theory, the coupling equation between two modes (core conduction mode and surface plasmon mode) can be expressed as:
wherein, beta1Is the propagation constant and beta of the guided mode of the fiber core2Is the transmission constant of the surface plasmon mode, E1Optical fiberElectric field of core conduction mode, is E2Is the electric field of the surface plasmon mode, k is the coupling strength, and z is the transmission length.
We assume the coupling mode transmission constant to be β, E1And E2Can be represented as E1Aexp (i β z) and E2When we introduce Bexp (i β z) into equation (1), the propagation constant of the available coupling mode is:
wherein, betaave＝(β1+β2)/2，δ＝(β1-β2)/2. Since the refractive indices of the two modes are lower than that of the background material, they are leaky modes whose propagation constant β1And beta2Is complex, and thus δ may be expressed as δ ═ δ r + i δtWhen the fiber core guided mode and the metal surface plasmon mode satisfy the phase matching condition, the real parts of their refractive indices are equal, δ r is 0, and therefore, we can obtain:
δ2+k2＝-δt 2+k2 (3)
at this time no matter deltatAnd k, resonant coupling occurs between the fiber core conduction mode and the surface plasmon mode, but the coupling strength is weak.
When two parallel waveguides are close to each other, the power between two adjacent waveguides will be periodically converted to form a directional coupling waveguide system. The conventional dual-core optical fiber has a dual-core structure equivalent to two parallel optical waveguides, and when the two parallel optical waveguides are close and coupled laterally, the optical power is periodically coupled from one waveguide into the other waveguide, and then returns to the incident waveguide, which is called mode coupling between the waveguides. The energy of two adjacent normal cylindrical optical waveguides which are parallel to each other can be coupled with each other, so that the field distribution of the two waveguides is changed, and the transverse coupling of the optical waveguides can be described by a mode coupling theory. Assuming that the two parallel adjacent cylindrical optical waveguides satisfy the weak coupling condition, the mode coupling equation is as follows:
wherein, a1(z)＝A1(z)exp(iβ1z)，a2(z)＝A2(z)exp(iβ2z)，K12And K21Is the coupling coefficient, beta, of the two waveguides1And beta2Is the transmission constant of both waveguides. | a1(z)|2，|a2(z)|2Representing the two core conduction mode powers, respectively. In general, when two cores are coupled for energy exchange, when the transmission fiber is very short, the dielectric loss can be ignored, and the total power of two conduction modes is unchanged, so that:
for the dual-core photonic crystal fiber designed in the paper, the two core structures are completely symmetrical, and the medium distribution is also the same, so that beta is enabled1＝β2＝β，K12＝K21K. Then the coupling equation (1) can be simplified as:
at the initial position Z of waveguide coupling equal to 0, a1(z)＝a1(0)，a2(z)＝a2(0) Then the solution of equation (6) is coupled:
the above equation shows that along the Z direction of beam propagation, the transmitted energy varies periodically between the two modes of propagation. Let a be given if a single waveguide has energy1(z)≠0，a2(z) ═ 0 available:
when k iszWhen pi/2, | a1(z)|20, and | a2(z)|2Not equal to 0. Thus, when z ═ pi/2 k, the power of conduction mode 1 has all coupled into mode 2. The distance required for a complete coupling of the transmission power from one waveguide to another is thus defined as the coupling length Lc:
two parallel waveguides with the same medium and symmetrical structure can be seen as two fiber cores of the dual-core photonic crystal fiber, and the dual-core coupling fiber has two types of eigenmodes, one type is a symmetrical mode (even mode) with field distribution of Es (x, y), and the other type is an anti-symmetrical mode (odd mode) Ea (x, y). Their propagation transmissions are β s ═ β + k and β a ═ β -k, respectively, and thus the coupling length can be expressed as:
the mode of the dual-core photonic crystal fiber can be seen as a superposition of four supermodes, namely symmetric supermodes (even supermode) Esx (x, y) and Esy (x, y) in the x and y polarization directions and anti-symmetric supermodes (odd supermode) Eax (x, y) and Eay (x, y) in the x and y polarization directions, and corresponding propagation constants are respectively:
the fiber coupling length obtainable according to equation (10) is therefore:
wherein,
and
the effective refractive indices of the even and odd supermodes in the x and y polarization directions, respectively. L isxAnd LyCoupling lengths in the x and y polarization directions, respectively.
When the optical fiber coupling length satisfies L-mLx＝nLyIf m and n are positive integers with different parity, a polarization beam splitter can be realized, and the coupling length in this case is also called the beam splitting length. It can be seen that when m/n is 1/2 or 2/1, the optimal splitting length, i.e., the shortest splitting length, can be obtained.
As shown in fig. 2, since the surface plasmon resonance effect occurs after gold is filled into the structure, the 2-step spp mode is coupled with the fundamental mode to change the effective refractive index of the supermode. The x-polarization even mode, the y-polarization odd mode and the y-polarization even mode have sudden change at respective resonance wavelengths, and the change of the x-polarization odd mode is small. The beam splitting effect of the device is greatly enhanced.
As shown in fig. 3, the coupling length and coupling length ratio characteristics of the x, y polarizations of the present invention can be seen. The coupling length of the x, y polarizations decreases with increasing wavelength. Coupling length ratios close to 2 are a crucial factor in the performance of fiber polarization splitters. The coupling length ratio decreases with increasing wavelength, nearest 2 at wavelength 1550 nm.
As shown in fig. 4, when the length of the optical fiber is 62.5 μm, the energy of x-polarized light at a wavelength of 1550nm reaches a maximum in one core, while the light of y-polarized light reaches a maximum in the other core, and the two lights are completely separated.
As shown in FIG. 5, it can be seen from the graph that the extinction ratio at 1550nm wavelength can be-76 dB, the wavelength range of the extinction ratio less than-20 dB is 1.50 μm to 1.61 μm, the bandwidth can reach 110nm, and the extinction ratio and the bandwidth are relatively large.
As specific examples: the minor axis dx1 of the central elliptical air hole ranged from 0.5 μm; the major axis dy1 ranges from 1 μm. The distance lambda 2 between the 2 gold-filled elliptical air holes and the upper side and the lower side of the central air hole in the vertical direction is 1.5 mu m, and the range of the long axis dx2 is 1 mu m; the minor axis dy2 ranges from 0.5 μm. The distance Lambda 1 between the 2 elliptical air holes and the left side and the right side of the central air hole in the horizontal direction is 1.11 mu m, and the range of the long axis is 1.6 mu m; the minor axis ranged from 1 μm. The air hole diameter d of the cladding region is in the range of 1 μm. The hole pitch Λ 1 of the cladding region was in the range of 1.11 μm.
The beam splitter introduces SPR effect, is shorter than a full air hole type photonic crystal fiber, and has better light splitting effect. The length of the optical fiber of the beam splitter is only 62.5 mu m, and the extinction ratio at the wavelength of 1550nm can reach-76 dB. The beam splitter has wider communication wave band and can realize single polarization output within the wavelength range of 1.50-1.61 mu m. The invention overcomes the defects of large volume, low extinction ratio, narrow bandwidth and the like of the traditional polarization beam splitter, and meets the requirements of a future full optical network with super-large capacity and easy integration.
The above-described embodiments of the apparatus are merely illustrative, and the units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. The utility model provides an ultrashort two-core photonic crystal fiber polarization beam splitter based on gold is filled which characterized in that includes: a core region and a cladding region filled with a pure quartz glass base material;
the core region comprises a first elliptical hole, two second elliptical holes and two third elliptical holes; wherein the first elliptical hole is located in the center of the core region, the minor axis diameter of the first elliptical hole is dx1, the major axis diameter is dy1, and air is in the first elliptical hole; the two second elliptical holes are respectively arranged on the upper side and the lower side of the first elliptical hole in the vertical direction, the vertical distance from the two second elliptical holes to the first elliptical hole is lambada 2, the diameter of the long axis of each second elliptical hole is dx2, the diameter of the short axis of each second elliptical hole is dy2, and metal gold is filled in the two second elliptical holes; the left side and the right side of the first elliptical hole in the horizontal direction are respectively provided with a first fiber core and a second fiber core of the optical fiber, and the horizontal distance between the center of the first fiber core and the center of the second fiber core and the first elliptical hole is lambada 1; the two third elliptical holes are respectively arranged on the left side and the right side of the first fiber core and the second fiber core in the horizontal direction, the horizontal distance between the two third elliptical holes and the centers of the first fiber core and the second fiber core is Lambda 1, the minor axis diameter of each third elliptical hole is dx3, the major axis diameter is dy3, and air is filled in each third elliptical hole; wherein dx1 ═ dy2< dx3, dy1 ═ dx2< dy 3;
the cladding region is positioned on the outer layer of the core region and comprises a plurality of uniformly arranged first round air holes and second round air holes; the first air round holes are uniformly distributed on the upper side and the lower side of the first elliptical hole, the first air round holes are arranged in an upper regular trapezoid structure and a lower regular trapezoid structure, the diameter of each first air round hole is d, the hole spacing is inverted V1, and the hole spacing between the third elliptical hole and the first air round holes adjacent to the upper side and the lower side in the vertical direction is inverted V2; the second air round holes are uniformly distributed on the outer sides of the two third elliptical holes, the diameters of the second air round holes are d, the hole intervals are Λ 1, and the hole intervals between the second air round holes and the first air round holes adjacent to the upper side and the lower side of the vertical direction are Λ 2; where d ═ dx3, Λ 1< Λ 2.
2. The beam splitter as claimed in claim 1 wherein: the minor axis diameter dx1 of the first elliptical hole ranges from 0.45 to 0.55 μm.
3. The beam splitter as claimed in claim 1 wherein: the value range of the major axis diameter dy1 of the first elliptical hole is 0.95-1.05 μm.
4. The beam splitter as claimed in claim 1 wherein: the value range of the major axis diameter dx2 of the second elliptical hole is 0.95-1.05 μm.
5. The beam splitter as claimed in claim 1 wherein: the minor axis diameter dy2 of the second elliptical hole ranges from 0.45 to 0.55 μm.
6. The beam splitter as claimed in claim 1 wherein: the minor axis diameter dx3 of the third elliptical hole ranges from 0.95 to 1.05 μm.
7. The beam splitter as claimed in claim 1 wherein: the value range of the major axis diameter dy3 of the third elliptical hole is 1.55-1.65 μm.
8. The beam splitter as claimed in claim 1 wherein: the diameter d of the first air round hole and the second air round hole ranges from 0.95 to 1.05 microns.
9. The beam splitter as claimed in claim 1 wherein: the value range of the distance Lambda 1 between the first air round holes is 1.109-1.111 mu m.
10. The beam splitter as claimed in claim 1 wherein: the value range of the lambda 2 is 1.45-1.55 mu m.
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| CN113359227B (en) * | 2021-06-29 | 2022-11-08 | 华北水利水电大学 | High-sensitivity double-core double-sample synchronous detection photonic crystal optical fiber sensor |
| CN113589427B (en) * | 2021-07-28 | 2022-08-26 | 北京邮电大学 | Double-core photonic crystal fiber polarization beam splitter |
| CN114488386A (en) * | 2022-01-20 | 2022-05-13 | 南京南辉智能光学感控研究院有限公司 | Ultra-wideband dual-core photonic crystal fiber based on silver filling |
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