阅读说明：本技术 一种基于pt对称结构与磁光子晶体的可调谐单向交叉波导分配器 (It is a kind of based on the tunable single of PT symmetrical structure and magnetic photonic crystal to crossing waveguide distributor ) 是由 张晓萌 余观夏 梅长彤 朱剑刚 赵莉 于 2019-09-27 设计创作，主要内容包括：本发明公开了一种基于PT对称结构与磁光子晶体的可调谐单向交叉波导分配器,属于微型光电子器件领域。其包括介质基板,第一、二、三、四阵列分别位于介质基板的四角,并形成具有四个端口的十字交叉的光子晶体波导,第一阵列和第四阵列的靠近交叉波导中心的拐角处分别设置第一增益柱和第二增益柱,第二阵列和第三阵列的靠近交叉波导中心的拐角处分别设置第一损耗柱和第二损耗柱,第一增益柱、第二增益柱与第一损耗柱、第二损耗柱满足宇称-时间对称条件,第一阵列、第二阵列、第三阵列和第四阵列根据需要分别施加外磁场。本发明的波导分配器在不同的外磁场下,可实现电磁波在设计的任意1～4个通道的选择传播,也可在任意通道实现电磁的局域化。(The invention discloses a kind of tunable singles based on PT symmetrical structure and magnetic photonic crystal to crossing waveguide distributor, belongs to microoptoelectronic device field.It includes medium substrate, first, two, three, four arrays are located at the quadrangle of medium substrate, and form the photonic crystal waveguide for having the right-angled intersection there are four port, the first gain column and the second gain column is respectively set in the corner at the close crossing waveguide center of the first array and the 4th array, the first loss column and the second loss column is respectively set in the corner at the close crossing waveguide center of second array and third array, first gain column, second gain column and the first loss column, second loss column meets parity-time symmetric condition, first array, second array, third array and the 4th array apply external magnetic field respectively as needed.Waveguide distributor of the invention is under different external magnetic fields, it can be achieved that electromagnetic wave can also realize the localization of electromagnetism in any channel in the selection propagation in any 1~4 channel of design.)

1. it is a kind of based on the tunable single of PT symmetrical structure and magnetic photonic crystal to crossing waveguide distributor, including medium substrate and Photonic crystal cylindrical-array on the medium substrate, which is characterized in that the photonic crystal cylindrical-array includes It is located at the first array (1), second array (2), third array (3) and the 4th array of the quadrangle of the medium substrate (4), there are four ports for first array (1), second array (2), third array (3) and the 4th array (4) formation tool The turning at the close crossing waveguide center of the photonic crystal waveguide of right-angled intersection, first array (1) and the 4th array (4) Place is respectively set the first gain column (9) and the second gain column (12), the second array (2) and third array (3) it is close The first loss column (10) and the second loss column (11), the first gain column is respectively set in the corner at crossing waveguide center (9) and gain-state, first loss column (10) and the second loss column is presented in the second gain column (12) under pump light (11) it is presented high loss state in no pump light, the first gain column (9), the second gain column (12) and described the One loss column (10), the second loss column (11) meet parity-time symmetric condition, first array (1), second array (2), third array (3) and the 4th array (4) apply external magnetic field respectively as needed.

2. the tunable single according to claim 1 based on PT symmetrical structure and magnetic photonic crystal is distributed to crossing waveguide Device, which is characterized in that first array (1), second array (2), the photon of third array (3) and the 4th array (4) are brilliant Scapus material is magnetic photonic crystal.

3. the tunable single according to claim 2 based on PT symmetrical structure and magnetic photonic crystal is distributed to crossing waveguide Device, which is characterized in that the magnetic photonic crystal is ferrite yttrium iron garnet；Its relative dielectric constant is 15 under externally-applied magnetic field ε₀, ε₀For permittivity of vacuum, relative permeability is tensor form,1600 Gausses' Under static external magnetic field, μ₁=14, μ₂=± 12.4, μ₂Direction determine that i is imaginary unit by the direction of external magnetic field.

4. the tunable single according to claim 1 based on PT symmetrical structure and magnetic photonic crystal is distributed to crossing waveguide Device, which is characterized in that the first array (1), second array (2), third array (3) and the 4th array (4) is that lattice is normal Number is the tetragonal structure of a,；The first gain column (9), the first loss column (10), the second loss column (11) and second Gain column (12) is single row configuration.

5. the tunable single according to claim 4 based on PT symmetrical structure and magnetic photonic crystal is distributed to crossing waveguide Device, which is characterized in that the radius of photonic crystal column is 0.145a.

6. the tunable single according to claim 4 based on PT symmetrical structure and magnetic photonic crystal is distributed to crossing waveguide Device, which is characterized in that the cylinder spacing of the single row configuration is a, and the radius of cylinder is 0.20a.

7. the tunable single according to claim 1 based on PT symmetrical structure and magnetic photonic crystal is distributed to crossing waveguide Device, which is characterized in that the relative dielectric constant of the first gain column (9) and the second gain column (12) is 9-0.25i, described The first loss column (10) and the relative dielectric constant of the second loss column (11) be 9+0.25i, i is imaginary unit, gain column with The relative permeability that column is lost is 1.

8. the tunable single according to claim 4 based on PT symmetrical structure and magnetic photonic crystal is distributed to crossing waveguide Device, which is characterized in that the width of the photonic crystal waveguide of the right-angled intersection is 0.6a~1.5a.

Technical field

The invention belongs to microoptoelectronic device fields, specifically, being related to a kind of based on PT symmetrical structure and magneto-optic The tunable single of crystal is to crossing waveguide distributor.

Background technique

In recent years, man-made band gap material especially photonic crystal is due to its superior performance, it has also become New Generation of Intelligent material The topological property of the research focus of material, especially man-made band gap material is even more to get more and more people's extensive concerning, distinctive robust Boundary state, transmission characteristic that backscattering inhibit immune with defect, potential application foreground are huge.

In quantum-mechanical system, if the Hamilton of systemMeetAnd withOperator With common eigenvector, then system has the non-PT symmetry broken and lacked, i.e. the potential function of Hamilton meets real part couple Claim and imaginary part odd symmetry is the necessary not a sufficient condition that system has non-broken scarce PT (parity-time) symmetry, otherwise is lacked to be broken PT symmetry.

Although PT symmetry quantum mechanics field meaning still under study for action, have in these basic conceptions part can To be realized in optics.Gain material and dissipative material are added in photonic crystal waveguide, due to Wave guide system gain material and The complex index of dissipative material meets the condition and refractive index real part phase of refractive index real part even symmetry and imaginary part odd symmetry simultaneously With and imaginary part on the contrary, may be constructed PT balanced system in waveguide system.In recent years, the symmetrical optical waveguide system of PT is found to have Many unique optical properties have important application value, PT symmetric system in terms of photon information processing and integrated optics The optical transport of the numerous unusual appearances occurred in system such as light energy oscillatory occurences, nonreciprocity, signal amplification transmission enhancing, light every From etc., there is huge potential application.

The magneto-opto photonic crystal made of magneto-optic memory technique has the asymmetric permeability tensor of frequency dependence.Outer plus straight It flows under magnetic field, magneto-optic memory technique has the anisotropy magnetic conductivity or permittivity tensor of the asymmetric off-diagonal element of nonzero sum.Energy Band structure is the distinctive attribute of photonic crystal, under the effect of outer static magnetic field, the photon of anisotropic properties magneto-optic memory technique composition Crystal forbidden band is opened in Dirac point, forms unidirectional side state, has broken time reversal, shows the unidirectional of single group velocity Propagation characteristic.

Magneto-optic memory technique is combined with PT structure, forms a kind of peculiar controllable new material structure.This structure is applied to Special optical propagation characteristic can be generated in 2 D photon crystal and waveguide design.

Publication date is that the Chinese patent 201410363260.5 on October 15th, 2014 discloses one kind based on photonic crystal The cross circulator of waveguide, signal can enter from 4 ports, but can only export from orthogonal adjacent port；It is open Day is that the Chinese patent 201410515362.4 on April 29th, 2015 discloses a kind of six port photon crystal rings shape of compact Device can only equally enter although there are six ports from port, export from adjacent port, be unable to control the side of signal output It to the quantity with signal output channels, can only unidirectionally enter, determine that direction unidirectionally exports, signal output mode is single.

Summary of the invention

In view of the above-mentioned problems existing in the prior art, the purpose of the present invention is to provide one kind to be based on PT symmetrical structure and magnetic Single-port signal input may be implemented to crossing waveguide distributor in the tunable single of photonic crystal, and the controllable port of signal exports, The transmission in the different channels such as L-type, T-type, horizontal type may be implemented, in addition when signal function is at center, there are many transmission sides Formula realizes the diversification of signal output mode.

To solve the above-mentioned problems, the technical solution adopted in the present invention is as follows:

It is a kind of based on the tunable single of PT symmetrical structure and magnetic photonic crystal to crossing waveguide distributor, including medium substrate With the photonic crystal cylindrical-array being located on the medium substrate, the photonic crystal cylindrical-array includes being located at institute The first array, second array, third array and the 4th array of the quadrangle for the medium substrate stated, first array, second Array, third array and the 4th array form tool there are four the photonic crystal waveguide of the right-angled intersection of port, and described first gust The corner at the close crossing waveguide center of column and the 4th array is respectively set the first gain column and the second gain column, and described the The first loss column and the second loss column is respectively set in the corner at the close crossing waveguide center of two arrays and third array, described The first gain column and the second gain column be presented gain-state under pump light, the first loss column and the second loss column exist There is no that high loss state is presented when pump light, the first gain column, the second gain column and first the loss column, second Loss column meets parity-time symmetric condition, and first array, second array, third array and the 4th array are according to need To apply external magnetic field respectively.

Further, the photonic crystal column material of first array, second array, third array and the 4th array is Magnetic photonic crystal.

Further, the magnetic photonic crystal is ferrite yttrium iron garnet；It is normal with respect to dielectric under externally-applied magnetic field Number is 15 ε₀, ε₀For permittivity of vacuum, relative permeability is tensor form,1600 Under the static external magnetic field of Gauss, μ₁=14, μ₂=± 12.4, μ₂Direction determine that i is imaginary unit by the direction of external magnetic field.

Further, first array, second array, third array and the 4th array be lattice constant be a just Square lattice structure,；First gain column, the first loss column, the second loss column and the second gain column is single row configuration.

Further, the radius of photonic crystal column is 0.145a.

Further, the cylinder spacing of the single row configuration is a, and the radius of cylinder is 0.20a.

Further, the relative dielectric constant of the first gain column and the second gain column is 9-0.25i, described the The relative dielectric constant of one loss column and the second loss column is 9+0.25i, and i is imaginary unit, and gain column is opposite with loss column Magnetic conductivity is 1.

Further, the width of the photonic crystal waveguide of the right-angled intersection is 0.6a~1.5a.

Compared with the prior art, the invention has the benefit that

(1) tunable single of the invention amplifies to crossing waveguide distributor combination magnet-optical medium and PT symmetrical structure signal It is complete to realize signal transmission direction by the change of the four positive negative directions of partial photonic crystal cylindrical-array externally-applied magnetic field for advantage Controllably, when single-port enters, the property of can choose is exported from single channel or multiple channels, and signal can be with orthogonal standard 0 ° of bending output of Helicopter-9, can also be exported with T-type and straight channel exports, this has wide in design optical integrated device and optical communication system Wealthy application prospect；When point dynamite source is at center, it can realize that any single channel is defeated by the variation of externally-applied magnetic field Out, transversely or longitudinally two channel output, when four parts all do not have externally-applied magnetic field, it is entirely defeated to may be implemented four-way signal Out；When additional same direction magnetic field, it can be achieved that the localization of optical signal and the storage of electromagnetic signal.

(2) tunable single of the invention is the unidirectional boundary transmission characteristic and PT of magneto-optic memory technique to crossing waveguide distributor Symmetrical structure, nonreciprocal transport property are protected by topology, which is different from common unilateral state, but when breaking simultaneously Between unilateral state in nonreciprocity forbidden band caused by inversion symmetry and inversion symmetry, there is apparent robustness so Transmit it is highly stable, not because barrier there are due to change unidirectional transmission property；Back scattering inhibitory effect is good simultaneously, non-inequality Property effect is obvious；The direction of propagation of unilateral state can be arbitrarily controlled by outer magnetic field direction.

(3) present invention is using magneto-optic memory technique and PT symmetrical structure time and space inversion asymmetry, and it is special to generate Unidirectional boundary state, and this optical device with topological structure, have high signal-to-noise ratio, are greatly improved device performance, and And for immune deficiency, the requirement to machining accuracy by topology protection is not harsh, independent of extreme laboratory environment, Transmission performance is stablized.

(4) power splitter of magneto-optic memory technique of the invention belongs to micromechanical devices, and size is in Nano grade, efficiency of transmission Height is, it can be achieved that integrated.

Detailed description of the invention

Fig. 1 is the structural schematic diagram of tunable single of the invention to crossing waveguide distributor；

In figure: 1, the first array；2, second array；3, third array；4, the 4th array；5, first passage；6, second is logical Road；7, third channel；8, fourth lane；9, the first gain column；10, the first loss column；11, the second loss column；12, the second gain Column.

Fig. 2 is the energy band diagram that super born of the same parents are obtained using upper just lower negative external magnetic field.

Fig. 3 is the steady-state field Ez that embodiment 1 obtains.

Fig. 4 is the steady-state field Ez that embodiment 2 obtains.

Fig. 5 is the steady-state field Ez that embodiment 3 obtains.

Fig. 6 is the steady-state field Ez that embodiment 4 obtains.

Fig. 7~10 are the steady-state field Ez that embodiment 5 obtains；

Fig. 7 is the first array 1 and the additional negative direction magnetic field of second array 2, third array 3 and the additional pros of the 4th array 4 To magnetic field；Fig. 8 is the first array 1 and the additional positive direction magnetic field of second array 2, third array 3 and the additional negative direction of the 4th array 4 Magnetic field；Fig. 9 is the first array 1 and the additional positive direction magnetic field of third array 3, second array 2 and the additional negative direction magnetic of the 4th array 4 ；Figure 10 is the first array 1 and the additional negative direction magnetic field of third array 3, second array 2 and the additional positive direction magnetic of the 4th array 4 .

Figure 11~16 are the steady-state field Ez that embodiment 6 obtains；

Figure 11 is the first array 1 and the additional positive direction magnetic field of the 4th array 4, second array 2 and the additional losing side of third array 3 To magnetic field；Figure 12 is the first array 1 and the additional negative direction magnetic field of the 4th array 4, second array 2 and the additional pros of third array 3 To magnetic field；Figure 13 is the additional negative direction magnetic field of second array 2, the additional positive direction magnetic field of third array 3, and the first array 1 and the Four arrays 4 not externally-applied magnetic field；Figure 14 is the additional positive direction magnetic field of the first array 1, the additional negative direction magnetic field of the 4th array 4, and the Two arrays 2 and third array 3 not externally-applied magnetic field；Figure 15 is the additional negative direction magnetic field of the first array 1, the additional pros of the 4th array 4 To magnetic field, and second array 2 and third array 3 not externally-applied magnetic field；Figure 16 is the additional positive direction magnetic field of second array 2, third battle array The additional negative direction magnetic field of column 3, and the first array 1 and the 4th array 4 not externally-applied magnetic field.

Figure 17~20 are the steady-state field Ez that embodiment 7 obtains；

Only have the additional negative direction magnetic field of the first array 1 in Figure 17, only have the additional negative direction magnetic field of the 4th array 4 in Figure 18, Only have the additional positive direction magnetic field of the 4th array 4 in Figure 19, only has the additional negative direction magnetic field of third array 3 in Figure 20.

Figure 21 is the steady-state field Ez that embodiment 8 obtains.

Figure 22 is the steady-state field Ez that embodiment 9 obtains.

Specific embodiment

The present invention is further described below combined with specific embodiments below.

A kind of tunable single based on PT symmetrical structure and gyromagnet photonic crystal as shown in Figure 1 is distributed to crossing waveguide Device, the photonic crystal cylindrical-array including medium substrate and on medium substrate, medium substrate are rectangle, upper left, the right side Above, lower-left, four part of bottom right is equipped with photonic crystal cylindrical-array, is the first array 1, second array 2, third array 3 respectively With the 4th array 4, which is the ferrite yttrium iron garnet column (YIG) of tetragonal, lattice constant a, relatively Dielectric constant is ε₁=15 ε₀, the radius of cylinder is 0.145a.

First array 1, second array 2, third array 3 and the 4th array 4 form tool, and there are four the right-angled intersections of port The first gain column is respectively set in the corner at the close crossing waveguide center of photonic crystal waveguide, the first array 1 and the 4th array 4 9 and the second gain column 12, the first damage is respectively set in the corner at the close crossing waveguide center of second array 2 and third array 3 Column 10 and the second loss column 11 are consumed, the distance between two neighboring gain column or two loss columns are also a, gain column and loss column Radius be 0.20a.Gain-state, the first loss 10 He of column is presented in first gain column 9 and the second gain column 12 under pump light High loss state, the first gain column 9, the second gain column 12 and the first loss column are presented in no pump light for second loss column 11 10, the second loss column 11 meets parity-time (PT) symmetric condition, and column structure in optical system is lost in row's gain column and a row At local PT structure, its main feature is that: relative dielectric constant is made of real and imaginary parts, for its relative dielectric constant of gain cylinder For 9-0.25*i, loss its relative dielectric constant of cylinder is 9+0.25*i.

It is first passage 5 between first gain column 9 and the first loss column 10, between the first array 1 and the second loss column 11 It is third channel 7, the second loss column 11 and the second gain between the first loss column 10 and the second gain column 12 for second channel 6 It is fourth lane 8 between column 12, the width in four channels can change between 0.6a~1.5a, in the embodiment of the present invention In, the width in four channels is 1.5a.

Magnetic is not added in first array 1, second array 2, third array 3 and 4 property of can choose externally-applied magnetic field of the 4th array , it can be acted on the magnetic field in additional positive or negative direction, point source, that is, optical signal when externally-applied magnetic field in channel arbitrarily a bit Or four passways, the signal property of can choose can also add from 4 any one entrance of port at the center of cross waveguide It carries.

It is broken in scarce system in parity or Time-reversal symmetry, the solution of wave equation may go out in non-paired form It is existing, to single-pass phenomenon occur, in optics, as can in analogy electronic system integer quantum Hall effect optics it is corresponding, Single-pass boundary state present in magneto-opto photonic crystal, just because of its constant translational symmetry and inversion symmetry and Caused by breaking scarce Time-reversal symmetry, in terms of Condensed Matter Physics, it is made of in recent years in one kind loss and gain material Model in, destroy parity (space inversion) and Time-reversal symmetry respectively but be that parity-time is symmetrical, light can be made The phenomenon that generating the transmission of non-heterogeneite.Namely our this systems can break time reversal and inversion symmetry simultaneously Property, this but also we design system in nonreciprocity laser propagation effect clearly, and be by topology protect, have Anti-interference and cut-through object function, transmission are stablized.

When no magnetic fields, ferritic magnetic conductivity is μ₀=1, when there is the effect of 0.16T steady bias magnetic field, can draw The anisotropy for the gyromagnet for sending out strong, so that the magnetic conductivity of magneto-optic YIG material shows as tensor form:

The boundary scheme of 2 D photon crystal can be obtained by improved plane wave expansion method.By maxwell equation group Middle cancellation magnetic-field component obtains:

In equation

Using the Bloch principle of periodic structure, electric field component can be unfolded as follows:

K is the wave vector of the Bloch wave inside first Brillouin-Zone in above-mentioned equation, and G is periodic structure reciprocal space Lattice vector, the expansion coefficient of the corresponding G of E (k+G).Element in permeability tensor can be launched into Fourier space form:

In the equation:

Wherein Au is the Eugene Wigner-Sai Ci primitive unit cell area in periodic structure.Continue to calculate and finally obtain following equations:

The sum of the infinite multiple vector of falling lattice G ' in formula.Above-mentioned equation is the eigenvalue equation of matrix, when we first determine One wave vector k, by the corresponding characteristic equation of a matrix group of a k.For given wave vector k, corresponding feature angular frequency is solved Rate can obtain the energy band of periodic structure, and the corresponding frequency of boundary scheme can solve completely.

Then we calculate band structure according to the above method, and super born of the same parents are used upper just lower negative external magnetic field by us first, Calculated energy band diagram is as shown in Figure 2, it can be seen that unidirectional dispersion curve occurs, unidirectional energy band represents a direction Group velocity.There is unidirectional boundary transmission mode in representative, exactly constrains in the surface wave on magneto-opto photonic crystal boundary, it can be flowed (or group velocity) is only directed to a direction, therefore one-way transmission may be implemented in structure of the invention.

When the frequency that we take in unilateral state frequency domain certain to put realizes the one-way transmission of electromagnetic signal, while we can Externally-applied magnetic field is controlled to realize that optical signal dynamically stores and transmits, and the anti-interference with unidirectional boundary state, Ke Yitou It crosses obstacle and stablizes transmission.After the exchange of the direction of our externally-applied magnetic fields, i.e., top exceptionally adds negative direction magnetic field, and lower part exceptionally adds just The band structure that direction magnetic field solves completely on the contrary, shown the completely opposite unidirectional energy band of group velocity occur, work as by this explanation The direction of top and the bottom externally-applied magnetic field exchanges, and the direction of obtained one-way transmission is completely opposite.

According to the above results, point source can be arranged in the inlet in four channels, also can be set in cross wave by we Tunable signal transmission is realized at the center led.It is upper just to descend negative sense right when there is externally-applied magnetic field for any one channel Transmission, it is upper it is negative under just transmit to the left, with just or with negative not transmitting.When not having externally-applied magnetic field up and down, channel letter is closed and can be passed It is defeated.