CN105607304A - Photonic crystal T-shaped waveguide-based horizontal output magnetic control alternative light path switch - Google Patents

Abstract

The invention discloses a photonic crystal T-shaped waveguide-based horizontal output magnetic control alternative light path switch which comprises a photonic crystal T-shaped waveguide with a TE forbidden band. The light path switch further comprises an input end (1), two output ends (2, 3), a background silicon dielectric cylinder (4), isosceles right triangle defect dielectric cylinders (5), a defect dielectric cylinder (6) and an electromagnet (7) for supplying offset magnetic field, wherein the input end (1) is arranged at the left end of the photonic crystal T-shaped waveguide; the output ends (2, 3) are respectively located at the right end and upper end of the photonic crystal T-shaped waveguide and are arranged in a horizontal line; the defect dielectric cylinder (6) is located at a central interaction of the T-shaped waveguide; the photonic crystal T-shaped waveguide is used for inputting the TE carrier light through the port (1) and then outputting the amplitude modulating light from the port (2) or the port (3). The photonic crystal T-shaped waveguide-based horizontal output magnetic control alternative light path switch is small in structure volume, is convenient in integration and is capable of efficiently realizing the function of alternative light path switch.

Description

Based on the horizontal output magnetic control alternative light path switch of the T-shaped waveguide of photonic crystal

Technical field

The present invention relates to magnetic control alternative light path gating switch, relate in particular to a kind of based on the T-shaped ripple of photonic crystalThe horizontal output magnetic control alternative light path gating switch of leading.

Background technology

What traditional magnetic control alternative light path gating switch was applied is geometric optical theory, and therefore volume all comparesLight path cannot be used for integrated greatly. The combination of magneto-optic memory technique and New-type photon crystal causes having proposed much lightSub-device, its topmost character is the gyromagnet nonreciprocity that electromagnetic wave shows under bias magnetic field, makes magneticPhotonic crystal not only has optically-active characteristic, also has larger transmission bandwidth and the propagation efficiency of Geng Gao. With lightSub-crystal is the small device on basis, for example magnetic control alternative light path gating switch, its photon crystal wave-guideBuild by lead-in defect. Photoswitch is the basic element of character of optic communication and optical computing, has extensivelyUsing value, compact photoswitch is the elementary cell of integrated optical circuit chip.

Summary of the invention

The object of the invention is to overcome deficiency of the prior art, provide a kind of efficient short distance to be convenient to integrated lightSub-crystal magnetic control alternative light path gating switch.

Object of the present invention is achieved by following technical proposals.

The horizontal output magnetic control alternative light path switch that the present invention is based on the T-shaped waveguide of photonic crystal, comprises oneThere is the T-shaped waveguide of photonic crystal in TE forbidden band; Described light path switch also comprises that an input 1, two are defeatedGo out end 2,3, background silicon medium post 4, isosceles right triangle defective media post 5 and defective media post 6, instituteState light path switch and also comprise an electromagnet that bias magnetic field is provided; The left end of the T-shaped waveguide of described photonic crystalFor input 1, described output 2 and output 3 lay respectively at lower end and the upper end of the T-shaped waveguide of photonic crystal,Be a horizontal line layout; Described defective media post 6 is positioned at T-shaped waveguide core infall; Described 4 isoscelesRight angled triangle defective media post 5 lays respectively at four corners that T-shaped waveguide intersects; Described photonic crystalWaveguide is by port one input TE light, and described switch 10 control signals are exported from port 2 or port 3 respectively again,Be that port one is selected to be connected with port 3 with port 2.

Described photoswitch further comprises wire 8, polarity controllable current source 9 and electronic switch 10; Electromagnet(7) the other end is connected with the other end of polarity controllable current source (9) by wire (8); The described utmost pointProperty controllable current source 9 is connected with electronic switch 10.

Described photonic crystal is Two dimensional square lattice structure.

Described photonic crystal is made up of high refractive index medium material and low-index material; Described high index of refraction is situated betweenMaterial is the medium that silicon or refractive index are greater than 2; Described low refractive index dielectric is that air or refractive index are less than 1.4Medium.

Described T-shaped waveguide is the structure removing in photonic crystal after a middle horizontally-arranged and a vertical setting of types medium post.

Described T-shaped waveguide intersects 4 background media posts of corner, and to delete respectively an angle straight to form isoscelesAngle triangle defect medium post, this isosceles right triangle defective media post 5 is triangle column type.

Described background silicon medium post 4 be shaped as square.

Described square silicon medium post is rotated counterclockwise 41 degree with medium mast axis z direction of principal axis.

Described defective media post 6 is ferrite square column, and it is shaped as square, described ferrite square columnMagnetic conductivity is anisotropy, and is subject to the control of bias magnetic field, and bias magnetic field direction is along the axle of ferrite square columnLine direction.

The present invention compared with prior art has advantages of following:

(1) structural volume is little, and switch time, response was fast, and light transmissioning efficiency is high, is applicable to extensive light path integrated;

(2) can short distance realize efficiently TE optical signal magnetic control alternative light path gating switch, be convenient toIntegrated and efficient, there is great practical value.

(3) characteristic that application photonic crystal can equal proportion convergent-divergent, changes the method for lattice paprmeter by equal proportion,Can realize the function of different wave length magnetic control alternative light path gating switch.

(4) high-contrast, high-isolation also has wider operating wavelength range simultaneously, can allowThe pulse of certain spectrum width, or Gauss light, or the light work of different wave length, or the light of multiple wavelength is simultaneouslyWork, has Practical significance.

Brief description of the drawings

Fig. 1 is the one knot of the horizontal output magnetic control alternative light path switch of the T-shaped waveguide of photonic crystal of the present inventionStructure schematic diagram.

In figure: input 1 output 2 output 3 background silicon medium post 4 isosceles right trianglesDefective media post 5 defective media posts 6

Fig. 2 is the another kind of the horizontal output magnetic control alternative light path switch of the T-shaped waveguide of photonic crystal of the present inventionStructural representation.

In figure: electromagnet 7 wire 8 polarity controllable current source 9 electronic switches 10

Fig. 3 is that the horizontal output magnetic control alternative light path switch structural parameters of the T-shaped waveguide of photonic crystal of the present invention divideButut.

Fig. 4 is the switch ripple of the horizontal output magnetic control alternative light path switch of the T-shaped waveguide of photonic crystal of the present inventionShape figure.

Fig. 5 (a) is that the horizontal output magnetic control alternative light path switch of the T-shaped waveguide of photonic crystal in embodiment 1 is prohibitedWith the switch contrast ratio figure of frequency.

Fig. 5 (b) is that the horizontal output magnetic control alternative light path switch of the T-shaped waveguide of photonic crystal in embodiment 1 is prohibitedWith the switch isolation degree figure of frequency.

Fig. 6 (a) is that the horizontal output magnetic control alternative light path switch of the T-shaped waveguide of photonic crystal in embodiment 2 is prohibitedWith the switch contrast ratio figure of frequency.

Fig. 6 (b) is that the horizontal output magnetic control alternative light path switch of the T-shaped waveguide of photonic crystal in embodiment 2 is prohibitedWith the switch isolation degree figure of frequency.

Fig. 7 (a) is that the horizontal output magnetic control alternative light path switch of the T-shaped waveguide of photonic crystal in embodiment 3 is prohibitedWith the switch contrast ratio figure of frequency.

Fig. 7 (b) is that the horizontal output magnetic control alternative light path switch of the T-shaped waveguide of photonic crystal in embodiment 3 is prohibitedWith the switch isolation degree figure of frequency.

Fig. 8 is that the light field of the horizontal output magnetic control alternative light path switch of the T-shaped waveguide of photonic crystal of the present invention is dividedCloth schematic diagram.

Detailed description of the invention

As shown in Figure 1, the horizontal output magnetic control alternative light path switch of the T-shaped waveguide of photonic crystal of the present inventionStructural representation (deleting biasing circuit and bias coil), comprises a photonic crystal T with TE forbidden bandType waveguide, light path switch also comprise an input 1, two outputs 2,3, background silicon medium post 4, etc.Waist right angled triangle defective media post 5 and defective media post 6; This device initialize signal light enters from left port onePenetrate, port 2 output light-waves, port 3 is isolated light wave; The left end of the T-shaped waveguide of photonic crystal is input 1,Output 2,3 lays respectively at lower end, the upper end of the T-shaped waveguide of photonic crystal, is a horizontal line layout; PhotonCrystal waveguide is by port one input TE light, and switch (10) control signal is more respectively from port 2 or port (3)Output, port one is selected to be connected with port 3 with port 2; Background silicon medium post 4 is shaped as square,The vertical paper of optical axis direction is outside, and isosceles right triangle defective media post 5 is, T-shaped waveguide intersects corner4 background media posts delete respectively an angle to form isosceles right triangle defective media post, these isoscelesRight angled triangle defective media post 5 is triangle column type, 4 isosceles right triangle defective media post 5 positions respectivelyFour corners of intersecting in T-shaped waveguide, optical axis direction is identical with background media post, 6, defective media postIn T-shaped waveguide core infall, defective media post 6 is ferrite square column, and it is shaped as square, optical axisThe vertical paper of direction is outside; The magnetic conductivity of this ferrite square column is anisotropy, and is subject to the control of bias magnetic field,Bias magnetic field direction is along the axis direction of ferrite square column. As shown in Figure 2, photonic crystal of the present invention is T-shapedThe structural representation of the horizontal output magnetic control alternative light path switch of waveguide (contains biasing circuit and offset lineCircle), light path switch comprises an electromagnet 7 (electromagnet coil) that bias magnetic field is provided, this electromagnet anotherOne end is connected with the other end of polarity controllable current source 9, and light path is opened and also comprised wire 8, polarity controllable currentSource 9 and electronic switch 10, one end of electromagnet 7 is one end phase with polarity controllable current source 9 by wire 8Connect; Polarity controllable current source 9 is connected with electronic switch 10; Light path switch of the present invention is as Fig. 1 and Fig. 3 instituteShow and adopt Descartes rectangular coordinate system: x axle positive direction be level to the right; Y axle positive direction is vertical in paperUpwards; Z axle positive direction is outside perpendicular to paper.

As shown in Figure 3, the relevant parameter of this device is:

d₁=a (lattice paprmeter)

d₂=0.3a (the square silicon post length of side)

d₃=0.2817a (the square defect post length of side)

d₄=0.3a (isosceles right triangle defect post waist is long)

d₅=1.2997a (isosceles right triangle defect post hypotenuse is to the distance at square defect post center)

d₆=1.577a (the wide length of waveguide)

Photonic crystal of the present invention is tetragonal, and lattice paprmeter is a, and the medium post length of side is 0.3a, at photon crystalline substanceBody square silicon medium post blank medium mast axis direction (z axle) is rotated counterclockwise 41 while spending, adopts planeWave spread method obtains TE forbidden band structure in photonic crystal, photon TE forbidden band be 0.3150 to0.4548 (ω a/2 π c), the light wave of any frequency in the middle of it will be limited in waveguide, tetragonal mediumPost blank medium mast axis direction (z axle) is rotated counterclockwise after 41 degree, has obtained larger wider forbidden band modelEnclose.

Silicon Medium Wave Guide used herein need to be deleted a line and a row medium post and form guided wave waveguide. RippleGuiding plane is perpendicular to the axis of the medium post in photonic crystal. By in the T-shaped waveguide core of above-mentioned photonic crystalInfall is introduced a ferrite square column (square defective media post 6), and its length of side is 0.28a, and 4 isosceles are straightAngle triangle defect medium post 5 inclined edge surfaces divide the distance that is clipped to ferrite column (square defective media post 6) axisFor 1.2997a. The optical axis of ferrite square column is consistent with the optical axis direction of background media post.

Principle introduction of the present invention is explained mainly for magnet-optical medium. Ferrite is a kind of magnetic anisotropyMaterial, ferritic magnetic anisotropy is induced by external dc bias magnetic place. This magnetic field makes iron oxygenMagnetic dipole in body follows same direction and arranges, thereby produces synthetic magnetic dipole moment, and magnetic dipole is existedUnder the frequency of being controlled by biased magnetic field strength, do precession. Can control with additional by adjusting biased magnetic field strengthThe interaction of microwave signal, thus realize the horizontal output magnetic control alternative light path of the T-shaped waveguide of photonic crystalSwitch. Under the effect of bias magnetic field, ferritic permeability tensor shows as asymmetry, wherein iron oxygenBody tensor permeability [μ] is:

$\[\mathrm{\μ}\]={\mathrm{\μ}}_0\[U\]+\[\mathrm{\χ}\]=\left(\begin{array}{ccc}\mathrm{\μ}& jk& 0\\ -jk& \mathrm{\μ}& 0\\ 0& 0& {\mathrm{\μ}}_0\end{array}\right)$ (Biasing) (1)

The matrix element of permeability tensor is provided by following formula:

ω_m＝μ₀γM_s(3)

ω＝2πf(4)

$\mathrm{\μ}={\mathrm{\μ}}_0(1+\frac{{\mathrm{\ω}}_0{\mathrm{\ω}}_m}{{\mathrm{\ω}}_0^2-{\mathrm{\ω}}^2})---\left(5\right)$

$k={\mathrm{\μ}}_0\frac{{\mathrm{\ω\ω}}_m}{{\mathrm{\ω}}_0^2-{\mathrm{\ω}}^2}---\left(6\right)$

Wherein, μ₀For the magnetic conductivity in vacuum, γ is gyromagnetic ratio, H₀For externally-applied magnetic field, M_SFor saturation magnetization,For operating frequency, p=k/ μ is normalization magnetization frequency, is also separation factor, and parameter μ and k determine notSame Ferrite Material, the material with the permeability tensor of this form is called gyromagnetism, supposes biasingDirection is contrary, H₀And M_SBy reindexing, so direction of rotation also can be contrary.

Bias magnetic field is produced by biased electrical magnet, in biased electrical magnet, loads bias current, and this bias current isControl signal; Bias current is for just (bearing) value, and a light path is in gating (closing), another light path placeIn closing (gating).

Meet H=H by regulating the size of bias magnetic field H to determine₀Time, light is exported from port 3, H=-H₀Time, light is exported from port 2. Thereby realize magnetic control alternative light path gating switch.

Magnetic control alternative light path gating switch, generally realizes: by the following method under bias magnetic field, by lightThe forbidden photon band of sub-crystal and photon Local Characteristic combine with the gyromagnet characteristic of magnet-optical medium, utilize faradayRotation effect, makes light rotate needed angle, is exported by any one port in two ports, makes endThe light intensity of mouth output can change, thereby has realized the effect of photoswitch.

Scan and calculate by numerical value, d₂＝0.3a，d₃＝0.2817a，d₅=1.2997a, normalization light waveFrequency f=0.4121, relative dielectric constant ε_r=12.9, optical signal is exported maximum from port 2, and from port3 outputs are minimum. In the time that bias magnetic field direction changes, H₀And M_SSign modification, make the annular side of optical signalTo changing. Therefore, optical signal is exported maximum from port 3, and minimum from port 2 outputs.

When introducing after above-mentioned defect in silicon medium post Waveguide array, incoming signal port is positioned at shown in Fig. 1 leftThe position of side's port one, this port one place is TE optical signal. Optical signal is in the medium post battle array with silicon medium post 4In the waveguide that row form, propagate, TE optical signal arrives after the defective locations of defective media post 6, TE optical signalTo all pass through, last TE optical signal will be in output port 2 position outputs; TE optical signal is at output portAlmost does not export 3 positions. Meanwhile, in waveguide, insertion loss is very little. Now port 2 is conducting state,Port 3 is in closed condition. In the time that bias magnetic field direction changes, incoming signal port is positioned at shown in Fig. 1 leftThe position of side's port one, this port one place is TE optical signal. Optical signal is in the medium post battle array with silicon medium post 4In the waveguide that row form, propagate, TE optical signal arrives after the defective locations of defective media post 6, TE optical signalTo all pass through, last TE optical signal will be in output port 3 position outputs; TE optical signal is at output portAlmost does not export 2 positions. Meanwhile, in waveguide, insertion loss is very little. Now port 3 is conducting state,Port 2 is in closed condition.

For choosing of lattice paprmeter and operation wavelength, can determine in the following ways. Pass through formula

$\mathrm{\λ}={\mathrm{\λ}}_{norm}a=\frac{a}{f_{norm}}---\left(7\right)$

Wherein with tetragonal silicon structure in the present invention normalization forbidden band frequency range

f_norm＝0.3150～0.4548(8)

Calculating corresponding forbidden band wave-length coverage is:

λ＝2.1987a～3.1746a(9)

In the situation that not considering that dispersion or material dispersion variation are very little, can pass through to change lattice as can be seen hereThe value of constant a obtains the λ value that meets wave-length coverage with its equal proportion. Operation wavelength can not considered dispersionOr regulate by medium intercolumniation lattice paprmeter in the insignificant situation of dispersion.

As shown in Figure 4, by controlling voltage, obtain luminous power output waveform, wherein 0～t₁Period magnetic field is-H,Export from port 2; T > t₁Period magnetic field is H, exports from port 3. Switch rise time T_rAnd fall timeT_fDepend on the pace of change in magnetic field.

The parameter of photoswitch:

(1) (are decided by the switch rise time of this structure, fall time switch rise time, fall timeThe pace of change in magnetic field, can obtain high-speed switch process like this, generally only needs the switch time of 1us. ) ginsengAccording to Fig. 4.

(2) switch contrast ratio is defined as:

Port 2 conductings: 10log (power output when power output/disconnection when conducting)=10log (P_Open/P_Close)

Port 3 conductings: 10log (power output when power output/disconnection when conducting)=10log (P_Open/P_Close)，With reference to Fig. 5 (a).

(3) isolation is defined as: isolation=10log (input power/isolation end power output)=

10log(P_Enter/P_Every), with reference to Fig. 5 (b).

Known with reference to Fig. 5 (a), in the time of normalization frequency of light wave ω a/2 π c=0.4121, its switch contrast ratio canReach 48dB.

Known by Fig. 5 (b), port 2,3 isolations can reach 48dB, and its performance is compared other photoswitchThere is clear superiority.

Embodiment 1

In the present embodiment, in the situation that not considering that dispersion or material dispersion variation are very little, change by equal proportionBecome the method for lattice paprmeter, can realize the function of different wave length magnetic control alternative light path gating switch. Order ginsengNumber a=6.1772 × 10^-3[m]，d₂＝0.3a，d₃＝0.2817a，d₅＝1.2997a，μ＝9.6125，P=0.7792, normalization frequency of light wave ω a/2 π c=0.4121, other parameter constants, make it correspond to 20GHzLight wave. With reference to Fig. 5 (a), obtain the switch contrast ratio within the scope of the frequency of light wave of forbidden band by simulation calculationFigure, with reference to Fig. 5 (b), the switch isolation degree figure within the scope of the frequency of light wave of forbidden band, this structure has high contrastThe magnetic control alternative light path gating switch of degree, high-isolation, thus realize light switch function.

Embodiment 2

In the present embodiment, in the situation that not considering that dispersion or material dispersion variation are very little, change by equal proportionBecome the method for lattice paprmeter, can realize the function of different wave length magnetic control alternative light path gating switch. Order ginsengNumber a=4.1181 × 10^-3[m]，d₂＝0.3a，d₃＝0.2817a，d₅＝1.2997a，μ＝9.6125，P=0.7792, normalization frequency of light wave ω a/2 π c=0.4121, other parameter constants, make it correspond to 30GHzLight wave. With reference to Fig. 6 (a), obtain the switch contrast ratio within the scope of the frequency of light wave of forbidden band by simulation calculation;With reference to Fig. 6 (b), the switch isolation degree within the scope of the frequency of light wave of forbidden band, this structure have high-contrast, high everyFrom the magnetic control alternative light path gating switch of degree, thereby realize light switch function.

Embodiment 3

In the present embodiment, in the situation that not considering that dispersion or material dispersion variation are very little, change by equal proportionBecome the method for lattice paprmeter, can realize the function of different wave length magnetic control alternative light path gating switch. Order ginsengNumber a=3.0886 × 10^-3[m]，d₂＝0.3a，d₃＝0.2817a，d₅＝1.2997a，μ＝9.6125，P=0.7792, normalization frequency of light wave ω a/2 π c=0.4121, other parameter constants, make it correspond to 40GHzLight wave. With reference to Fig. 7 (a), obtain the switch contrast ratio in the frequency range of forbidden band by simulation calculation; ReferenceFig. 7 (b), the switch isolation degree figure in the frequency range of forbidden band. Known by Fig. 7 (a), Fig. 7 (b), at normalizingWhile changing frequency of light wave ω a/2 π c=0.4121, by finite element software, COMSOL calculates, the light field obtainingSimulation drawing, as shown in Figure 8. Hence one can see that, and TE light is transmitted to respectively port 2 and port 3 efficiently, shouldStructure has the magnetic control alternative light path gating switch of high-contrast, high-isolation, thereby has realized photoswitchFunction.

The above the present invention all has improvements in detailed description of the invention and range of application, not should be understood toThe present invention is limited.

Claims (9)

1. the horizontal output magnetic control alternative light path switch based on the T-shaped waveguide of photonic crystal,It is characterized in that, comprise a T-shaped waveguide of photonic crystal with TE forbidden band; Described light pathSwitch also comprise an input (1), two outputs (2,3), background silicon medium post (4),Isosceles right triangle defective media post (5) and defective media post (6), described light path switchAlso comprise an electromagnet (7) that bias magnetic field is provided; A left side for the T-shaped waveguide of described photonic crystalEnd is for input (1), and described output (2,3) lays respectively at the T-shaped waveguide of photonic crystalLower end, upper end, be a horizontal line layout; Described defective media post (6) is positioned at T-shaped waveguideCenter infall; Described 4 isosceles right triangle defective media posts (5) lay respectively at TFour corners that type waveguide intersects; Described photon crystal wave-guide is inputted TE light by port (1),Output signal is from port (2) or port (3) output, and port (1) is selected and port (2)Be connected with port (3).

2. according to the horizontal output magnetic based on the T-shaped waveguide of photonic crystal claimed in claim 1Control alternative light path switch, is characterized in that: described light path switch further comprise wire (8),Polarity controllable current source (9) and electronic switch (10); The other end of electromagnet (7) passes throughWire (8) is connected with the other end of polarity controllable current source (9); Described polarity controllable electricStream source (9) is connected with electronic switch (10).

3. according to the horizontal output magnetic based on the T-shaped waveguide of photonic crystal claimed in claim 1Control alternative light path switch, is characterized in that: described photonic crystal is Two dimensional square lattice structure.

4. according to the horizontal output magnetic based on the T-shaped waveguide of photonic crystal claimed in claim 1Control alternative light path switch, is characterized in that: described photonic crystal is by high refractive index medium materialForm with low-index material; Described high refractive index medium material is that silicon or refractive index are greater than 2Medium; Described low refractive index dielectric is the medium that air or refractive index are less than 1.4.

5. according to the horizontal output magnetic based on the T-shaped waveguide of photonic crystal claimed in claim 1Control alternative light path switch, is characterized in that: described T-shaped waveguide is in removing in photonic crystalBetween structure after a horizontally-arranged and a vertical setting of types medium post.

6. according to the horizontal output magnetic based on the T-shaped waveguide of photonic crystal claimed in claim 1Control alternative light path switch, is characterized in that: described T-shaped waveguide intersects 4 back ofs the body of cornerScape medium post is deleted respectively an angle to form isosceles right triangle defective media post, these isoscelesRight angled triangle defective media post (5) is triangle column type.

7. according to the horizontal output magnetic based on the T-shaped waveguide of photonic crystal claimed in claim 1Control alternative light path switch, is characterized in that: being shaped as of described background silicon medium post (4)Square.

8. according to the horizontal output magnetic based on the T-shaped waveguide of photonic crystal claimed in claim 7Control alternative light path switch, is characterized in that: described square silicon medium post is with medium mast axisZ direction of principal axis is rotated counterclockwise 41 degree.

9. according to the horizontal output magnetic based on the T-shaped waveguide of photonic crystal claimed in claim 1Control alternative light path switch, is characterized in that: described defective media post (6) is ferrite sidePost, it is shaped as square, and the magnetic conductivity of described ferrite square column is anisotropy, and is subject toThe control of bias magnetic field, bias magnetic field direction is along the axis direction of ferrite square column.