CN100470302C - Photon crystal ratio light intensity light splitter - Google Patents
Photon crystal ratio light intensity light splitter Download PDFInfo
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- CN100470302C CN100470302C CNB2005100121153A CN200510012115A CN100470302C CN 100470302 C CN100470302 C CN 100470302C CN B2005100121153 A CNB2005100121153 A CN B2005100121153A CN 200510012115 A CN200510012115 A CN 200510012115A CN 100470302 C CN100470302 C CN 100470302C
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- waveguide
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Abstract
The present invention provides a kind of photon crystal proportional light intensity light splitter. Line fault is introduced into two-dimensional or three-dimensional photon crystal to constitute input waveguide and coupling waveguide, and by means of directional coupling principle, light intensity is distributed to the output ports the input waveguide and the coupling waveguide guide in the required proportion to realize proportional light splitting. The device is one one-stage or multiple-stage tree structure, and the two output light beams of the foregoing stage are the two input light beams of the next stage. The multiple-stage structure light splitter can split one light beam into two or more output light beams in the required light intensity proportion. The device has very low loss and efficiency near 100 %.
Description
Technical field
The present invention relates to the optical splitter of a kind of microwave and light wave, the light intensity of incident light can be divided in proportion multi-beam output.
Background technology
Photonic crystal is the artificial structure that dielectric is periodic arrangement, and its characteristic is to have photon band gap.Photon band gap is such frequency range, and the light that frequency drops in this scope can not exist in photonic crystal and propagate.And when original complete periodic structure is damaged partly, just constitute defective, and in photon band gap, introduce the defective mould, the light of corresponding frequencies will be limited in the scope of defective.If what constitute is line defect, light will be propagated along the direction of line defect, and can not turn over radius be bending of wavelength magnitude with almost having loss.Because photonic crystal has the ability of very good control light, it has numerous application prospects, such as micro-cavity laser, and photonic crystal fiber etc.The wherein the most noticeable integrated optics chip that is based on photonic crystal.Many integrated optical device that are suitable for based on photonic crystal are devised, and show good performance, such as wave filter, and photoswitch, wavelength division multiplex device or the like.Optical splitter is a very important assembly in the optical system.Two kinds of structures based on the optical splitter of photonic crystal once appearred in the past.A kind of is as shown in Figure 1 Y type optical splitter (document 1, S.Boscoloand M.Midrio, Y junctions in photonic crystal channel waveguides:high transmissionand impedance matching, Opt.Lett.v.27,1001 (2002)).This optical splitter utilizes the line defect of a Y shape, will import light and import to respectively in two branches.Because some light is reflected in bifurcation, so its efficiency ratio is lower.Another kind is the optical splitter (document 2 that utilizes guide directional coupling (directional coupling) character as shown in Figure 2, Insu Park et al.Photonic crystal power-splitter based on directional coupling, Opt.Express v.12,3599 (2004)).This optical splitter is provided with two symmetries and parallel waveguide in the input waveguide both sides, input light is the generation directional couple in the parallel zone of waveguide, consequently imports in the parallel waveguide that light is coupled to both sides and is introduced to two output ports.All about 47.6%, efficient is higher for the transmitance of two output ports (being defined as the output intensity of a port and the ratio of the incident intensity of optical splitter).Yet, the two bundle output light that these two kinds of optical splitters all can only provide light intensity to equate, thus limited its application in the occasion of the light that needs varying strength.
Summary of the invention
The objective of the invention is to propose a kind of photon crystal ratio light intensity light splitter, make it can be as required the energy of input light be pro rata distributed each output port, and further improve the service efficiency of optical splitter.
Technical scheme is as follows:
A kind of photon crystal ratio light intensity light splitter, comprise photonic crystal, the inlead defective constitutes in photonic crystal incident waveguide and coupled waveguide, there is one section directional couple district that length parallel to each other is l between described incident waveguide and the coupled waveguide, end in the directional couple district, the incident waveguide is connected to first output port, coupled waveguide is connected to second output port, input port is meant incident waveguide input port, it is characterized in that: this device is one or more levels tree structure, in multistage structure, the output intensity of upper level is as the input light intensity of next stage, and the pass of the ratio T of the output intensity of the output port of each grade and the incident intensity of input port and the length l in directional couple district is
T
1(l)＝cos
2[πl/(2L
c)]，
T
2(l)＝sin
2[πl(2L
c)]，
T in the formula
1Be the output intensity of first output port that links to each other with the incident waveguide and the ratio of incident port incident intensity, T
2Be the output intensity of second output port that links to each other with coupled waveguide and the ratio of incident port incident intensity, L
cIt is the distance that light intensity is coupled to the required experience of another waveguide fully from a waveguide in the directional couple district.
Technical characterictic of the present invention also is: two parallel waveguide spacings are 1～4 times of grating constant in the directional couple district of described each grade, and the distance between its adjacent output port is at least 8 times grating constant.
Photonic crystal of the present invention is tetragonal lattice or triangular crystal lattice is arranged; Described photonic crystal is two dimension or three-dimensional photon crystal structure.
The principle of utilizing directional couple of ratio optical splitter of the present invention is coupled to the effect that realizes beam split in two waveguides with the energy of a branch of light, output light intensity ratio can be carried out flexible design on demand, and do not have energy to be reflected back, can realize very high spectroscopical effeciency, near 100%.According to same principle, carry out beam split by the light that further will separate, can design the multistage ratio light intensity output optical splitter that is tree structure.Ratio light intensity light splitter of the present invention can be realized on two dimension or three-D photon crystal.
Description of drawings
Fig. 1: the structural representation of Y type optical splitter in the prior art.
Fig. 2: the directional couple optical splitter of the medium light intensity output of prior art.
The photon crystal ratio light intensity light splitter of Fig. 3: embodiment 1.
The strange mould that directional couple produces among Fig. 4: the embodiment 1 and the dispersion curve of even mould.
The output transmittance curve of photon crystal ratio light intensity light splitter two output ports of Fig. 5: embodiment 1.
Fig. 6: embodiment 2 has a ratio light intensity output optical splitter of 2 grades.
Wherein: 1,2 expression photon crystal wave-guide; 3 expression photonic crystals; 4 is input port; 5 and 6 is two output port: l, l
1, l
2, l
3The coupling length of representing each directional couple district; I
0, I
1, I
2, I
3, I
4, I
5, I
6, I
7The light intensity that inputs or outputs of representing different port.
Embodiment
Fig. 3 is the structural representation that has only the photon crystal ratio light intensity light splitter of one-level provided by the invention.Incident waveguide 1 is parallel in l length with coupled waveguide 2 among the figure, and the distance of 1～4 times of grating constant at interval, and this zone is called the directional couple district.Present embodiment adopts the distance of 2 times of grating constants.Light intensity is I
0Incident light directional couple here takes place.At directional couple district right-hand member, separately light intensity will be guided to corresponding first output port 5 and second output port 6 respectively in two waveguides.For the two-beam after the beam split can not interfered with each other, the spacing of leading to the waveguide of output port should be at 8 times more than the grating constant.Adopt among Fig. 3 and be spaced apart 12 times grating constant.Output intensity I
1And I
2Just equal the light intensity of the inherent directional couple of two waveguides district right-hand member.According to the orthogonal mode theory, in the zone that directional couple takes place, the propagation constant in the originally single waveguide is that the single mode of β will split into a strange mould and an even mould, and propagation constant is respectively β
OddAnd β
Even, their field distribution is odd symmetry and even symmetry respectively with respect to the plane between two parallel waveguides.The stack result of strange mould and even mould is to make light intensity switch back and forth in two waveguides.It is L that light intensity switches to the length that another waveguide experiences fully from a waveguide
c=π/| β
Odd-β
Even|, β wherein
OddAnd β
EvenCan utilize plane wave expansion method to calculate.In the directional couple district, the wave function of strange mould and even mould can be expressed as respectively in the waveguide 2:
E
odd，1＝(A/2)·exp[j(β
oddx-ωt)]， (1)
Wherein A is the amplitude of incident light, and ω and t are angular frequency and time,
The initial position that is Qi Mo and even mould differs, and the x axle is parallel to waveguide 2 and is starting point with the left end of waveguide 2.Total wave function E in the waveguide 2
2The strange mould that can be represented by (1) formula and (2) formula and the wave function addition of even mould obtain:
E
2＝E
odd,2+E
even，2(3)
So, through further shifting the light intensity that can obtain in the waveguide 2 distribution function onto along wave guide direction:
I(x)＝I
0sin
2[πx/(2L
c)]，(4)
I wherein
0It is light intensity from incident port 4 incident lights.Light intensity at the x=l place in the waveguide 2 will be introduced to output first output port 5, and remaining light intensity just is directed second output port 6 along waveguide 1.The transmitance of definition output port is the ratio that each port output intensity and optical splitter are imported light intensity, so the transmitance T of the output port of waveguide 1 and waveguide 2 correspondences (being respectively 6 among Fig. 3 and 5)
1And T
2Can be expressed as the function of the length l of directional couple respectively:
T
1(l)＝cos
2[πl/(2L
c)]， (5)
T
2(l)＝sin
2[πl/(2L
c)]. (6)
The allocation proportion of the light intensity of two output ports of photon crystal ratio light intensity light splitter like this, shown in Figure 3 can be set flexibly by the length of regulating directional couple.
Utilize the character of directional couple that each output intensity of optical splitter is further separated, can realize the optical splitter of multistage tree structure easily.According to the principle that the front is narrated, the light intensity of each output port is distributed can flexible design, thereby realizes the ratio light intensity light splitter (Fig. 6) more than 2 output intensities.
The present invention is further described below in conjunction with drawings and Examples:
Embodiment 1:
The photon crystal ratio light intensity light splitter that has only one-level, its structure as shown in Figure 3, the incident waveguide 1 and the coupled waveguide 2 that comprise photonic crystal 3, the inlead defective constitute in photonic crystal, l is the length of incident waveguide 1 and coupled waveguide 2 parallel zones among the figure, be directional couple length, this section zone is the directional couple district.The spacing distance of two photon crystal wave-guides is 2 times of grating constants in the directional couple district; Lead to output port waveguide be spaced apart 12 times grating constant.The structure of photonic crystal is arranged in airborne medium post for being tetragonal lattice, and the specific inductive capacity of medium post is ε=8.9, and radius is r=0.25a, and wherein a is a grating constant.This photonic crystal has the TM mould bandgap range of (direction of an electric field is parallel to the axial of medium post): a/ λ=0.29～0.39.The defective modal dispersion curve in directional couple district utilizes plane wave expansion method to calculate as shown in Figure 4.Can obtain from Fig. 4, when normalized frequency was the incident light incident of a/ λ=0.34, the strange mould in the directional couple district and the propagation constant of even mould were respectively: β
Odd=0.298 and β
Even=0.365, so L
c=π/| β
Odd-β
Even|=15.L
cSubstitution (5) formula and (6) formula, I when obtaining coupling length l and getting different values
1And I
2Shared incident intensity I
0Ratio, as shown in Figure 5.So, can be according to coupling length l is determined in the requirement of output intensity ratio according to Fig. 5.Such as obtaining I
1: I
2=0.25, can make l=10a; Make I
1: I
2=2.5, desirable l=24a; Make I
1: I
2=9, desirable l=26a.
Embodiment 2:
Photon crystal ratio light intensity light splitter with 2 grades, structure as shown in Figure 6, constitute by four waveguides, the part on the dotted line left side is a first order optical splitter among the figure, dotted line the right is two partial optical splitters, as the input light intensity of two optical splitters in the second level, the result of two-stage combination obtains the output light of 4 bundle varying strengths to two output intensities of first order optical splitter respectively.The structural parameters of photonic crystal are identical with embodiment's 1.The input light intensity I of the first order
3Through length is l
1First directional couple district after be divided into two-beam, this two-beam is l through length respectively as the input light of partial two branches again
2And l
3The directional couple district carry out further beam split, obtain four bundle output light: I at last
4, I
5, I
6And I
7Three coupling lengths are among the figure: l
1=21a, l
2=19a, l
3=18a.The ratio of the output intensity of four output ports is: I
4: I
5: I
6: I
7=7.5:0.22:1:6.
Claims (4)
1. photon crystal ratio light intensity light splitter, comprise photonic crystal (3), the inlead defective constitutes in photonic crystal incident waveguide (1) and coupled waveguide (2), there is one section directional couple district that length parallel to each other is l between described incident waveguide and the coupled waveguide, end in the directional couple district, the incident waveguide is connected to first output port, coupled waveguide is connected to second output port, input port is meant incident waveguide input port, it is characterized in that: this device is one or more levels tree structure, in multistage structure, the output intensity of upper level is as the input light intensity of next stage, and the pass of the ratio T of the output intensity of the output port of each grade and the incident intensity of input port and the length l in directional couple district is:
T
1(l)＝cos
2[πl/(2L
c)]，
T
2(l)＝sin
2[πl/(2L
c)]，
T in the formula
1Be the output intensity of first output port that links to each other with the incident waveguide and the ratio of input port place incident intensity, T
2Be the output intensity of second output port that links to each other with coupled waveguide and the ratio of input port place incident intensity, L
cIt is the distance that light intensity is coupled to the required experience of another waveguide fully from a waveguide in the directional couple district.
2. according to the described photon crystal ratio light intensity light splitter of claim 1, it is characterized in that: two parallel waveguide spacings are 1～4 times of grating constant in the directional couple district of described each grade, and the distance between its adjacent output port is at least 8 times grating constant.
3. according to claim 1 or 2 described photon crystal ratio light intensity light splitters, it is characterized in that: described photonic crystal is tetragonal lattice or triangular crystal lattice is arranged.
4. according to the described photon crystal ratio light intensity light splitter of claim 1, it is characterized in that: described photonic crystal is two dimension or three-dimensional photon crystal structure.
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| CNB2005100121153A CN100470302C (en) | 2005-07-08 | 2005-07-08 | Photon crystal ratio light intensity light splitter |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2005100121153A CN100470302C (en) | 2005-07-08 | 2005-07-08 | Photon crystal ratio light intensity light splitter |
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| CN100470302C true CN100470302C (en) | 2009-03-18 |
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Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102122026B (en) * | 2011-03-15 | 2012-06-27 | 中国科学院半导体研究所 | Photonic crystal surface state-based two-dimensional photonic crystal beam splitter |
| CN102967898B (en) * | 2012-12-19 | 2015-04-22 | 北京邮电大学 | Integrated photonic crystal multiplexer based on Y-type structure and bent waveguide |
| CN103941337B (en) * | 2014-02-22 | 2017-01-04 | 浙江大学 | Y type polarization filtering beam splitter based on isomorphism 2 D photon crystal |
| CN103941414A (en) * | 2014-02-22 | 2014-07-23 | 浙江大学 | Y-type polarization filtering beam splitter based on heterogeneous two-dimension photonic crystals |
| CN104570206B (en) * | 2015-01-09 | 2017-06-09 | 中国科学院大学 | Beam-splitting method based on photonic crystal standing wave resonance |
| CN106772795A (en) * | 2016-12-13 | 2017-05-31 | 北京邮电大学 | A kind of photonic crystals splitter structure of efficient multifrequency point 1 × 3 |
| CN108663748B (en) * | 2018-05-09 | 2019-12-06 | 上海大学 | Dual-channel drop filter based on single line defect resonant cavity |
| CN111025431B (en) * | 2019-12-11 | 2021-08-10 | 深圳市光科全息技术有限公司 | Three-dimensional photonic crystal and application thereof |
| CN112987294A (en) * | 2019-12-16 | 2021-06-18 | 杭州光粒科技有限公司 | Two-dimensional optical waveguide, virtual and real optical wave beam combiner and AR equipment |
| CN113917685A (en) * | 2021-09-30 | 2022-01-11 | 中航光电科技股份有限公司 | Energy directional coupling-based light splitting optical waveguide design method |
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