CN105353462B - Photon crystal filter with reflection cavity - Google Patents
Photon crystal filter with reflection cavity Download PDFInfo
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- CN105353462B CN105353462B CN201510931437.1A CN201510931437A CN105353462B CN 105353462 B CN105353462 B CN 105353462B CN 201510931437 A CN201510931437 A CN 201510931437A CN 105353462 B CN105353462 B CN 105353462B
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
- G02B6/122—Basic optical elements, e.g. light-guiding paths
- G02B6/1225—Basic optical elements, e.g. light-guiding paths comprising photonic band-gap structures or photonic lattices
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Abstract
A kind of photon crystal filter with reflection cavity, including 2 D photon crystal, the dielectric posts for removing a row of horizontal in the photonic crystal form horizontal waveguide, and removes the vertical dielectric posts of a row upwards since the center of the horizontal waveguide and form vertical waveguide, vertical waveguide is vertical output waveguide, vertical waveguide and the horizontal waveguide of the side of horizontal waveguide intersection location are horizontal input waveguide, vertical waveguide and the horizontal waveguide of the other side of horizontal waveguide intersection location are horizontal output waveguide, defect cavity is located at the close position adjacent with horizontal input waveguide in vertical output waveguide, reflection cavity is located at position adjacent with the vertical output waveguide in horizontal output waveguide, the reflection cavity includes five dielectric posts being arranged in order with defect cavity.The photon crystal filter reduces the scattering loss of waveguide and microcavity by adjusting the central medium column radius of defect cavity and reflection cavity so that the filter reaches optimum filtering effect, and transmitance is high, and Q values are also high.
Description
Technical field
The present invention relates to a kind of photon crystal filters.
Background technology
Photonic crystal is a kind of artificial micro-structure that the material by differing dielectric constant is constituted by periodic arrangement, basic
Characteristic is photon band gap, and the light wave that frequency is fallen in forbidden band will be unable to propagate, another characteristic is photon local, breaks photon crystalline substance
The periodic structure of body introduces certain defects, and the light wave to match with defect frequency will be by local in defect, due to photon crystalline substance
The good characteristic of body and it can control the good advantage of the propagation of light, structural compactness, photonic crystal in the dimensional space of very little
Filter, which is designed, for people provides strong tool.
Photon crystal micro cavity is the point defect for destroying photonic crystal periodic structure, and microcavity frequency is located at photonic band gap
Interior, light is by Complete Bind into microcavity, and theoretically the quality factor of microcavity can be very high, by adjusting the structure and parameter of microcavity,
The resonant frequency and pattern of microcavity can be changed, therefore microcavity is an ideal filtering device.
Chalcogenide glass is one kind based on elements such as sulphur, selenium, telluriums and optical material made from other elements is added, when responding
Between it is ultrafast, the response time is less than 100fs, and wherein luminous effect is less than 50fs, and nonlinear factor is high, third-order nonlinear optical coefficient n2Than
General oxide glass is much bigger, is 100-1000 times of silicon substrate.This kind of glass breaches Conventional optical communication and is widely used
The not high enough quartz glass of nonlinear factor, miniaturization and the high-performance of optical device may be implemented.In addition, chalcogenide glass is also
A kind of excellent infrared optical material, have it is wider it is infrared penetrate spectrum, it is different according to composition, through range from
0.5um~25um etc., include whole near-infrareds and most of mid infrared region through wave band, this is subsequent design near-infrared
And the photon crystal filter of mid infrared region provides possibility.
Invention content
A kind of high, Q values that the technical problem to be solved by the present invention is to transmitances also high photonic crystal with reflection cavity
Filter.
Technical solution is used by the present invention solves above-mentioned technical problem:A kind of photonic crystal filtering with reflection cavity
Device includes the 2 D photon crystal of multiple dielectric posts formation, it is characterised in that:Remove a row of horizontal in the 2 D photon crystal
Dielectric posts form horizontal waveguide, and remove the vertical dielectric posts of a row upwards since the center of the horizontal waveguide and formed vertically
Waveguide, the vertical waveguide are vertical output waveguide, the horizontal waveguide of the vertical waveguide and the side of horizontal waveguide intersection location
For horizontal input waveguide, the horizontal waveguide of the vertical waveguide and the other side of horizontal waveguide intersection location is horizontal output waveguide,
Defect cavity is located at the close position adjacent with horizontal input waveguide in vertical output waveguide, and reflection cavity is located in horizontal output waveguide
The position adjacent with the vertical output waveguide, the reflection cavity include five dielectric posts being arranged in order with defect cavity, wherein
The radius of the radius ratio four additional dielectric posts of centrally located central medium column is big, and four additional dielectric posts are located at two-by-two respectively
The both sides of central medium column.
Preferably, the 2 D photon crystal is tetragonal photonic crystal, and the medium of tetragonal photonic crystal
Column radius is 0.21a, and a is lattice constant, and the dielectric posts of tetragonal photonic crystal are chalcogenide glass matrix, and background is air.
Preferably, the radius of the central medium column in the defect cavity is 0.35a, and the radius of other four dielectric posts is
The radius of 0.21a, the central medium column in the reflection cavity are 0.4a, and the radius of other four dielectric posts is 0.21a.
Preferably, the lattice constant a=620nm of the tetragonal photonic crystal.
Compared with the prior art, the advantages of the present invention are as follows the central medium columns half by adjusting defect cavity and reflection cavity
Diameter reduces the scattering loss of waveguide and microcavity so that the filter is needing wave band to reach optimum filtering effect, and transmitance is high, Q
Value is also high.
Description of the drawings
Fig. 1 is the structural schematic diagram of the photon crystal filter with reflection cavity of the embodiment of the present invention.
Fig. 2 is the variation relation figure of the band gap width and medium column radius of the photon crystal filter of the embodiment of the present invention.
Fig. 3 is the band gap distribution map of perfect photonic crystal TM moulds.
Fig. 4 is that there are one the photonic crystal waveguide dispersion map of waveguide, wherein X-axis generations using the tool of plane wave expansion method emulation
Table wave vector, Y-axis represent normalized frequency.
Fig. 5 a are the stable state field strength of the photon crystal filter of areflexia chamber when inputting the high bass wave of 1550nm single wavelengths
Distribution map, Fig. 5 b are when inputting the high bass wave of 1550nm single wavelengths, to there is the stable state field strength of the photon crystal filter of reflection cavity
Distribution map.
Fig. 6 is schemed using the penetrating for the photon crystal filter corresponded in Fig. 5 a, 5b of Finite-Difference Time-Domain Method emulation,
Wherein dotted lines be areflexia chamber photon crystal filter H103 resin, dotted line be have reflection cavity photonic crystal filter
The H103 resin of wave device.
Fig. 7 is the time domain steady-state response figure of the photon crystal filter containing reflection cavity in corresponding diagram 6.
Specific implementation mode
Below in conjunction with attached drawing embodiment, present invention is further described in detail.
Fig. 1 is the photon crystal filter structure with reflection cavity of the embodiment of the present invention, including 2 D photon crystal 1,
Preferably, be tetragonal photonic crystal, there is on the 2 D photon crystal 1 horizontal input waveguide A, horizontal output waveguide B and
Vertical output waveguide C, the horizontal input waveguide A and horizontal output waveguide B are to remove a row of horizontal in tetragonal photonic crystal
Dielectric posts form horizontal waveguide and then formed, vertical output waveguide C is in tetragonal photonic crystal from horizontal waveguide
Center, which starts to remove the vertical horizontal media column of a row upwards, to be formed.Remove a row of horizontal in the tetragonal photonic crystal
Dielectric posts form horizontal waveguide, and removing the vertical dielectric posts of a row forms vertical wave upwards since horizontal waveguide centre
It leads, which is vertical output waveguide C, vertical output waveguide C and horizontal waveguide intersection location
Side is horizontal input waveguide A, and the other side is horizontal output waveguide B.The defect cavity 2 is located in vertical output waveguide C and level
Position adjacent input waveguide A, the reflection cavity 3 are located at adjacent with the vertical output waveguide C in horizontal output waveguide B.
Wherein the lattice constant of tetragonal photonic crystal is a=620nm, is along the square periodicity of X-Z plane point
The dielectric posts photonic crystal of cloth, medium column radius r=0.21a, dielectric posts are Ge33Sb10Se57Chalcogenide glass matrix, refractive index are
N=2.65, the third-order non-linear specific refractivity near 1550nm are 1.3 × 10-17m2/ W, non-linear absorption coefficient 1.6
×10-12M/W, non-linear is 590 times of quartz material.Background is air, refractive index 1.Defect cavity 2 is located at vertical output
The intersection of horizontal input waveguide A and vertical output waveguide C are closed in waveguide C, reflection cavity 3 is located in horizontal output waveguide B and faces
The intersection of nearly horizontal input waveguide A and horizontal output waveguide B.The Jie of defect cavity 2 and reflection cavity 3 by 5 arrangements in a row
Matter column is constituted, including is located at central medium column, remaining 4 are normal media column, are located at central medium column both sides two-by-two respectively.Its
The central medium column radius of middle defect cavity 2 is 0.35a, remaining four medium column radius is 0.21a.5 dielectric posts of reflection cavity 3
In, central medium column radius is 0.4a, remaining four medium column radius is 0.21a.Horizontal input waveguide A, horizontal output waveguide B
With the perpendicular relationships of vertical output waveguide C, signal light is inputted from the sides horizontal input waveguide A, is exported from vertical output waveguide B.
And the position of the dielectric posts in the position and photonic crystal of the dielectric posts of the defect cavity 2 and reflection cavity 3 matches, i.e. defect
The center of dielectric posts in chamber, reflection cavity is correspondingly aligned with the center of the dielectric posts in tetragonal photonic crystal.It is situated between
It does not move the center of matter column.
The technical scheme is that based on photon band gap characteristic and photon crystal micro cavity possessed by 2 D photon crystal
Local Characteristic, realize photon crystal filter filtering function.The basic principle of above-mentioned photon crystal filter is:Two dimension
Photonic crystal provides one, and there is wider photon band gap, the light wave that wavelength is fallen in the photon band gap will be unable in photon crystalline substance
It is propagated in body.As shown in Fig. 2, be under TM patterns, the medium column radius of Two dimensional square lattice photonic crystal and band gap width
Relationship is scanned the band gap distribution map that detection obtains, when medium column radius is less than 0.11a or is more than 0.42a, photonic crystal
There is no band gap;When medium column radius is since 0.11a, the width of photonic band gap increases with the increase of radius, works as Jie
When matter column radius increases to 0.21a, band gap width reaches maximum, and the normalized frequency (a/ λ) of maximum band gap is 0.352-
0.449, hereafter, with the increase of medium column radius, band gap width is gradually reduced, when medium column radius is more than 0.42a, band gap
It disappears, as a result, photonic crystal dielectric posts radius size when present invention selection band gap width maximum, is 0.21a.It is shown in Fig. 3
The band gap diagram of perfection photonic crystal when medium column radius is 0.21a, oblique line portion is photon band gap, corresponding normalized frequency a/ λ
=ω a/2 π c, wherein λ are the wavelength in vacuum, and ω is the angular frequency of light, and c is the light velocity in vacuum.The structure has two parts
Band gap, relatively narrow band gap normalized frequency (a/ λ) are 0.81-0.82, and the band gap width is too narrow, and it is relatively more tired to introduce defect mode
Difficulty, so mainly considering the broader band gap of following width, corresponding normalized frequency (a/ λ) is 0.352-0.449, center normalizing
It is 0.4 to change frequency, consistent with the result in Fig. 2.
By introducing line defect, line defect functions as waveguide, i.e., introduces certain defect state in photon band gap,
Meeting the light wave of defect frequency can propagate in the waveguide, and the waveguide dispersion figure of photonic crystal, returns when Fig. 4 is containing a waveguide
One changes waveguide at frequency 0.4, and there are a patterns, and to obtain resonance wavelength in 1550nm, according to formula f=a/ λ, we select
Photonic crystal lattice constant a=620nm.The present invention is devised such as the defects of Fig. 1 chambers 2 and reflection cavity 3, meets microcavity resonance frequency
The photon of rate will be by local into microcavity position, and the photon crystal micro cavity has very high quality factor, can deposit well
Storage meets the energy of the light wave of resonant frequency.The groundwork of the present invention is the central medium column radius of adjusting defect cavity, so that
Resonance wavelength is obtained in 1550nm, and defect cavity coupling efficiency is high, by a series of simulation calculation, dielectric posts radius is when center
0.35a, when remaining four medium column radius is 0.21a, the resonance wavelength of the defect cavity is 1550nm and coupling efficiency is higher, full
The design requirement of sufficient filter.
Horizontal output waveguide is blocked by designing reflection cavity 3, in the hope of reinforcing coupling efficiency of the defect cavity 2 to light, is reduced
Loss in filtering, to improve the Q values and filtering performance of defect cavity, ideally reflection cavity can be reflected in addition to it certainly
All waves other than body resonance wavelength, through the wave of its resonance wavelength, the inside of the reflection cavity 3 of design is made of 5 dielectric posts,
The central medium column radius for adjusting reflection cavity 3 obtains when center dielectric posts radius being 0.4a by a series of simulation calculation,
Central medium column both sides are respectively containing there are two in the case of normal media column, i.e., when the resonance wavelength of reflection cavity is 1700nm, no
It can cause the loss of light wave, the best performance of the filter.One signal light is set at the outboard end of horizontal input waveguide A,
One monitor is set at the outboard end of vertical output waveguide C.The signal light is defeated from horizontal input waveguide A in the form of high bass wave
Enter, coupling occurs with defect cavity 2 in vertical output waveguide C, when light wave reaches defect cavity 2, due to the local of microcavity
Frequency-selecting acts on, and only meeting the light wave that the defect cavity resonance wavelength is 1550nm could resonate, and be coupled into defect cavity 2,
And it is exported from vertical output waveguide C.
Fig. 5 a are the field intensity map when filter without containing reflection cavity 3 reaches stable state, and Fig. 5 b are to contain reflection cavity 3
Filter reaches field intensity map when stable state.Fig. 6 is to respectively illustrate through scheming corresponding to Fig. 5 with reflection cavity and not
Transmitance with reflection cavity.As shown in Fig. 5 a, 5b, 6, which realize is to wavelength
The filtering of the light wave of 1550nm, the transmitance of photon crystal filter is 0.98 when containing reflection cavity 3;When without containing reflection cavity
3, i.e., when being a waveguide at reflection cavity 3, the transmitance of photon crystal filter is less than 0.3, and reflection cavity 3 has blocked horizontal output wave
It leads so that most of light wave is reflected back toward horizontal input waveguide.According to the saturating of the photon crystal filter containing reflection cavity in Fig. 6
It crosses shown in figure, is the centre wavelength of mode of resonance according to formula Q=λ/Δ λ, wherein λ, Δ λ is the half-peak band width of mode of resonance, meter
The quality factor for calculating defect cavity, the Q value that can be calculated this defect cavity reach 7500, and description defect chamber has good
Storage capacity.Fig. 7 is the time domain steady-state response figure of the photon crystal filter corresponding to Fig. 5 (b) with reflection cavity 3, again
The vertical output end for demonstrating the photon crystal filter containing reflection cavity has very high transmitance.
For the present invention in order to adapt to the development of communication band, the filter carried is operated in 1550nm wavelength, has and actually answers
With value.And the photon crystal filter in the embodiment of the present invention, by the central medium column for adjusting defect cavity and reflection cavity
Radius reduces the scattering loss of waveguide and microcavity so that the filter reaches optimum filtering effect, and transmitance is high, and Q values are also high.
Claims (2)
1. a kind of photon crystal filter with reflection cavity includes the 2 D photon crystal (1) of multiple dielectric posts formation, special
Sign is:The dielectric posts for removing a row of horizontal in the 2 D photon crystal form horizontal waveguide, and from the horizontal waveguide
The heart starts to remove the vertical dielectric posts formation vertical waveguide of a row upwards, which is vertical output waveguide (C), this hangs down
The horizontal waveguide of straight wave guide and the side of horizontal waveguide intersection location is horizontal input waveguide (A), the vertical waveguide and horizontal wave
The horizontal waveguide for leading the other side of intersection location is horizontal output waveguide (B), and defect cavity (2) is located in vertical output waveguide (C)
The close position adjacent with horizontal input waveguide (A), reflection cavity (3) are located in horizontal output waveguide (B) and the vertical output wave
The adjacent position (C) is led, the reflection cavity (3) includes five dielectric posts being arranged in order with defect cavity (2), wherein in being located at
The radius of the radius ratio four additional dielectric posts of the central medium column of the heart is big, and four additional dielectric posts are located at center and are situated between two-by-two respectively
The both sides of matter column;
The 2 D photon crystal (1) is tetragonal photonic crystal, and the medium column radius of tetragonal photonic crystal is
0.21a, a are lattice constant, and the dielectric posts of tetragonal photonic crystal are chalcogenide glass matrix, and background is air;
The radius of central medium column in the defect cavity (2) is 0.35a, and the radius of other four dielectric posts is 0.21a, described
The radius of central medium column in reflection cavity (3) is 0.4a, and the radius of other four dielectric posts is 0.21a.
2. carrying the photon crystal filter of reflection cavity as described in claim 1, it is characterised in that:The tetragonal photon
The lattice constant a=620nm of crystal.
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CN108535197A (en) * | 2018-04-24 | 2018-09-14 | 南京信息工程大学 | A kind of detection device and method of miniature ethanol solution concentration |
CN109669240B (en) * | 2019-01-04 | 2020-10-02 | 深圳大学 | Photonic crystal waveguide hexapole splitting mode interference FANO resonance structure |
CN109669239B (en) * | 2019-01-04 | 2020-10-02 | 深圳大学 | Orthogonal splitting mode interference FANO resonance structure of photonic crystal waveguide |
CN109828329B (en) * | 2019-01-30 | 2024-03-01 | 广西师范大学 | Photonic crystal filter with double-bending L-shaped microcavity |
CN112346173A (en) * | 2020-11-05 | 2021-02-09 | 安徽熙泰智能科技有限公司 | Dielectric column photonic crystal optical waveguide turning grating structure and near-to-eye display system |
CN112925058B (en) * | 2021-01-22 | 2022-03-04 | 中山大学 | Photonic crystal narrow-band filter based on zero-dimensional topological angular state |
CN114325935B (en) * | 2021-12-08 | 2024-04-16 | 南京邮电大学 | Non-magnetic photon crystal non-reciprocal double-channel narrow-band filter |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
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CN102298172A (en) * | 2011-09-26 | 2011-12-28 | 上海理工大学 | Two-dimensional photonic crystal point defect-based tunable optical power distributor and working method |
CN103196866A (en) * | 2013-03-13 | 2013-07-10 | 上海理工大学 | Gas refractive index detector based on two-dimensional photonic crystal |
CN103472532A (en) * | 2013-09-13 | 2013-12-25 | 深圳大学 | Photonic crystal all-optical tunable filter |
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CN102298172A (en) * | 2011-09-26 | 2011-12-28 | 上海理工大学 | Two-dimensional photonic crystal point defect-based tunable optical power distributor and working method |
CN103196866A (en) * | 2013-03-13 | 2013-07-10 | 上海理工大学 | Gas refractive index detector based on two-dimensional photonic crystal |
CN103472532A (en) * | 2013-09-13 | 2013-12-25 | 深圳大学 | Photonic crystal all-optical tunable filter |
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