CN112114464A - Two-dimensional photonic crystal half adder - Google Patents
Two-dimensional photonic crystal half adder Download PDFInfo
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- CN112114464A CN112114464A CN202011022774.6A CN202011022774A CN112114464A CN 112114464 A CN112114464 A CN 112114464A CN 202011022774 A CN202011022774 A CN 202011022774A CN 112114464 A CN112114464 A CN 112114464A
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F3/00—Optical logic elements; Optical bistable devices
Abstract
The invention discloses a two-dimensional photonic crystal half adder, which consists of two waveguide beam splitters, a connecting waveguide, an optical XOR logic gate based on a two-dimensional photonic crystal AND an optical AND logic gate. The design structure works under the interference effect caused by the optical path difference. The input light is split into two beams by a ring coupler. One of the beams acts as an XOR gate and produces the output Sum. The other beam of light is used as an and gate and generates an output Carry. The invention provides a two-dimensional photonic crystal half adder which improves the contrast of a device and has lower response time and smaller size.
Description
Technical Field
The invention belongs to the field of two-dimensional photonic crystal devices, and particularly relates to a two-dimensional photonic crystal half adder.
Background
Due to the application of all-optical signal processing schemes in high-speed optical networks and optical computing, there is increasing interest. These schemes can increase the operating speed to megabits (Tbps) and greatly reduce power consumption, compared to conventional optical-electrical-optical (O-E-O) signal processing schemes. Moreover, they can handle large bandwidth signals, large information streams, and do not require O-E-O conversion. All-optical logic gates are of great significance in the fields of high-speed optical communication and networks. These logic gates designed on photonic crystal platforms will add further advantages such as compactness, low power consumption and high speed.
Photonic Crystals (PCs) are regular optical structures made of periodically arranged media of different refractive index. Such materials are capable of blocking photons of a particular frequency by virtue of having a photonic band gap, thereby affecting the movement of the photons. The photonic crystal can realize band-stop filtering by completely depending on the structure of the photonic crystal, and the structure is simpler. Photonic crystals can be classified into one-dimensional photonic crystals, two-dimensional photonic crystals, and three-dimensional photonic crystals according to the dimension of the photonic band gap of the photonic crystal in space. The advent of photonic crystals has made possible the "plenophotonics" of information processing technology and the miniaturization and integration of photonic technology.
A half adder designed on a photonic crystal is a combinational logic gate. Combinational logic gates have a more complex structure AND function than single gates such as AND, OR, NOT, XOR, NAND AND NOR. They tend to have multiple input and output ports and may be logically implemented by a combination of multiple single gates. Combinational logic gates are especially difficult to design, both to optimize structure and size, to improve device performance, and to balance cross-talk between ports. The performance of the logic gate is mainly considered in three aspects, namely, the size of the device is smaller, and the integration degree is higher. The response time of the structure, which is related to the speed of the gate and determines the number of bits that can be processed per unit time in the gate, is called the bit rate. Three is the contrast of the on and off logic levels, which determines the output level difference between the two states "0" and "1" logic. In recent years, a number of designs for half adders have been proposed, but it is often difficult to balance size, response time, and contrast.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide a two-dimensional photonic crystal half adder which improves the contrast ratio of a device and simultaneously has lower response time and smaller size.
In order to achieve the purpose, the invention is realized by adopting the following technical scheme: the invention provides a two-dimensional photonic crystal half adder, comprising: the optical waveguide optical fiber comprises a waveguide beam splitter, a connected waveguide, an optical XOR logic gate AND an optical AND logic gate.
Furthermore, the half adder is composed of two-dimensional photonic crystals, and the two-dimensional photonic crystals are formed by arranging triangular lattice dielectric column arrays in air.
Further, the dielectric pillars of the triangular lattice dielectric pillar array are cylindrical.
Further, the dielectric column radius r of the triangular lattice dielectric column array is 0.167a, and a is the lattice constant of the photonic crystal.
Further, the waveguide splitter includes a straight waveguide, a splitter point defect, and a ring coupler.
Furthermore, a 3 x 3 two-dimensional photonic crystal dielectric column is arranged inside the ring coupler.
Furthermore, the optical XOR logic gate is composed of an XOR logic gate point defect, two input ports, one output port and one input/output port.
Further, the optical AND logic gate is composed of an AND logic gate point defect, two input ports, one output port AND one input/output port.
Further, the connected waveguide is composed of a connected waveguide point defect and a bent waveguide.
Compared with the prior art, the invention has the following beneficial effects:
1. according to the invention, the AND logic gate AND the XOR logic gate which are completely AND independently separated in logic function originally establish a relation through the communication waveguide, AND the AND logic gate receives compensation from the XOR logic gate through the communication waveguide, so that the contrast of an output signal (C) end is obviously improved;
2. the present invention splits input light into two beams by a waveguide splitter. One of the beams acts as an XOR gate and produces the output Sum. The other beam of light is used as an AND gate and generates an output Carry; the two-dimensional photonic crystal half adder provided by the invention has lower response time, can calculate the data transmission rate of the two-dimensional photonic crystal half adder to be megabits (Tbps), has higher contrast ratio and smaller size;
3. the invention has compact structure, excellent performance, wider working frequency range, easy preparation and easy integration with other photonic crystal devices.
Drawings
FIG. 1 is a schematic structural view of the present invention;
fig. 2 is a y-direction electric field profile when the half-adder input a-B-1;
fig. 3 is a y-direction electric field profile for a half-adder input a equal to 1 and B equal to 0;
fig. 4 is a y-direction electric field profile when the half-adder input a is 0 and B is 1;
fig. 5 is a response curve of normalized power of the output port over time for a half-adder input a-B-1;
fig. 6 is a response curve of normalized power of the output port over time for a half-adder input a-1 and B-0;
fig. 7 is a response curve of normalized power of the output port over time for a half-adder input a-0 and B-1;
fig. 8 is a graph of normalized optical power distribution versus wavelength for a half-adder configuration in the a-B-1 input state;
fig. 9 is a graph of normalized optical power distribution versus wavelength for a half-adder configuration in the a-1 and B-0 input states;
fig. 10 is a graph of normalized optical power distribution versus wavelength for a half-adder configuration in the a-0 and B-1 input states;
fig. 11 is a response curve of normalized power of the output port of the half-adder in the a-B-1 input state over time with compensation turned off;
fig. 12 is a graph of normalized power response of the output port of the half-adder with input states of a-1 and B-0 over time with compensation turned off;
fig. 13 is a graph of normalized power response of the output port of the half-adder over time in the a-0 and B-1 input states when compensation is turned off.
Detailed Description
In the following description, for purposes of explanation, numerous implementation details are set forth in order to provide a thorough understanding of the various embodiments of the present invention. It should be understood, however, that these implementation details are not to be interpreted as limiting the invention. That is, in some embodiments of the invention, such implementation details are not necessary. In addition, some conventional structures and components are shown in simplified schematic form in the drawings.
The first embodiment is as follows:
as shown in fig. 1, the present embodiment provides a two-dimensional photonic crystal half-adder, which includes two waveguide splitters, a connected waveguide, an optical XOR logic gate AND an optical AND logic gate.
The two-dimensional photonic crystal is formed by arranging a triangular lattice dielectric column array in air, the refractive index is 1, the dielectric columns of the triangular lattice dielectric column array are cylindrical, the material is silicon dioxide, and the refractive index is 3.1. The dielectric column radius r of the triangular lattice dielectric column array is 0.167a, and a is the lattice constant of the photonic crystal.
As shown in fig. 1, the waveguide splitter comprises a straight waveguide, splitter point defect, ring coupler. The dielectric column radii of the beam splitter point defects are respectively that the radius of dielectric column R6 (dielectric column R7) is equal to 0.1169a, the radius of dielectric column R8 (dielectric column R10) is equal to 0.0835a, the radius of dielectric column R9 (dielectric column R11) is equal to 0.0835a, the radius of dielectric column R12 (dielectric column R14) is equal to 0.1336a, and the radius of dielectric column R13(15) is equal to 0.1503a, where a is the lattice constant of the two-dimensional photonic crystal. The inside of the ring coupler is a 3X 3 two-dimensional photonic crystal dielectric column.
The optical XOR logic gate consists of an XOR logic gate point defect, two input ports, one output port and one input/output port. The dielectric column radius of the XOR logic gate point defect is respectively that the radius of the dielectric column R21 is equal to 0.04175a, the radius of the dielectric column R22 is equal to 0.04175a, the radius of the dielectric column R23 is equal to 0.04175a, and the radius of the dielectric column R24 is equal to 0.097361a, wherein a is the lattice constant of the two-dimensional photonic crystal.
The optical AND logic gate consists of an AND logic gate point defect, two input ports, one output port AND one input-output port. The radius of the dielectric column of the AND logic gate point defect is respectively that the radius of the dielectric column R1 is equal to 0.0835a, the radius of the dielectric column R2 is equal to 0.0835a, the radius of the dielectric column R3 is equal to 0.0835a, the radius of the dielectric column R4 is equal to 0.0835a, AND the radius of the dielectric column R5 is equal to 0.1002a, wherein a is the lattice constant of the two-dimensional photonic crystal.
The connected waveguide consists of a connected waveguide point defect and a bent waveguide. The radiuses of the dielectric columns connected with the waveguide point defects are respectively that the radius of a dielectric column R16 is equal to 0.06346a, the radius of a dielectric column R17 is equal to 0.06346a, the radius of a dielectric column R18 is equal to 0.06346a, the radius of a dielectric column R19 is equal to 0.06346a, the radius of a dielectric column R20 is equal to 0.05344a, and a is the lattice constant of the two-dimensional photonic crystal.
The whole structure of the invention is triangular lattice, so the dielectric columns are all at the initial positions, in order to adjust the light scattering, the invention shifts the positions of the dielectric columns R12 and R14 to the right by 0.03674a on the basis of the positions of the original lattices, shifts the positions of the dielectric columns R13 and R15 to the right by 0.08684a from the positions of the original lattices, and shifts the position of the dielectric column R1 to the left by 0.00835a from the positions of the original lattices.
The half adder has an input signal (A) terminal, an input signal (B) terminal, an output signal (S) terminal, and an output signal (C) terminal. In analogy to conventional circuits, the optical power at the input and output ports is normalized, and normalized powers less than 0.15 are considered to be logical "0". Normalized powers greater than 0.40 are considered to be logical "1". The signal light at the input signal (a) end is divided into signal light a1 and signal light a2 by a coupler. The signal light at the input signal (B) end is divided into signal light B1 and signal light B2 by a coupler. The output at the output signal (S) terminal represents "Sum" (Sum), which is obtained by an XOR logical operation of the signal light a2 and the signal light B2. The output at the output signal (C) terminal represents "Carry", which is obtained by AND logical operation of the signal light a1 AND the signal light B1. Input light enters the waveguide from the input signal (a) side and the input signal (B) side and is then coupled to the ring resonator. The dielectric pillars R6 and R7 function to improve the coupling efficiency of the ring resonator. Dielectric pillars R12, R13, R14, AND R15 function to reduce crosstalk of light scattered back in AND XOR logic gates. The light from the coupler outlet is divided into signal lights A1\ B1 AND A2\ B2, enters logic gates XOR AND AND, AND is finally output from an output signal (S) end AND an output signal (C) end respectively. The XOR logic gates exploit the asymmetry of the structure to achieve destructive interference. AND logic gates exploit the symmetry of structures to achieve constructive interference. The function of the dielectric pillar R1 is to increase the power at the output signal (C) terminal. The waveguide formed by the irregular line defect passing through the dielectric pillar R16, the dielectric pillar R17, the dielectric pillar R18, the dielectric pillar R19 AND the dielectric pillar R20 is designed to guide the light scattered at the XOR to the AND, thereby increasing the optical power at the output signal (C) side. This design balances crosstalk loss and power compensation.
According to the optimization method, the following results are obtained through software simulation:
as shown in fig. 2, the electric field distribution in the y direction when the half-adder input a equals 1.
As shown in fig. 3, the electric field distribution in the y direction when the half-adder input a is 1 and B is 0 is shown.
As shown in fig. 4, the electric field distribution in the y direction when the half-adder input a is 0 and B is 1 is shown.
As shown in fig. 5, the response curve of normalized power of the output port over time is given when the half-adder input a ═ B ═ 1. The response time and normalized optical power of the structure can be obtained from the graph. As is clear from the curves, the states of the input signal (a) terminal AND the input signal (B) terminal are logic "1", AND because the enable port of the AND logic gate continuously receives the scattered light from the XOR logic gate through the connected waveguide, the output curve of the output signal (C) terminal in the figure continuously rises at 1ps (cT ═ 300 μm), which is significant for improving the contrast of the output signal (C) terminal.
As shown in fig. 6, changing the half-adder input a to 1 and B to 0 results in a response curve of normalized power at the output port over time.
As shown in fig. 7, changing the half-adder input a to 0 and B to 1 results in a response curve of normalized power at the output port over time.
As shown in fig. 8, the normalized optical power distribution of the half-adder structure in the input state of a ═ B ═ 1 changes with the wavelength, and the scanning wavelength band is 1520nm to 1550 nm.
As shown in fig. 9, changing the input state a of the half adder to 1 and B to 0 results in the variation of the normalized optical power distribution with wavelength, and the scanning wavelength band is 1520nm to 1550 nm.
As shown in fig. 10, changing the input state a of the half adder to 0 and B to 1 results in the variation of the normalized optical power distribution with wavelength, and the scanning wavelength band is 1520nm to 1550 nm.
As shown in fig. 11, in order to visually observe the increase of the "Carry" optical power of the output signal (C) end by the connected waveguide, the connected waveguide is closed, and the power compensation is turned off. The half-adder input a is set to 1 and B to 0, resulting in a response curve of normalized power of the output port over time without compensation.
As shown in fig. 12, changing the half-adder input state a to 1 and B to 0 results in a response curve of normalized power of the output port over time without compensation.
As shown in fig. 13, changing the half-adder input state a to 0 and B to 1 results in a response curve of normalized power of the output port over time without compensation.
The invention relates to a triangular lattice two-dimensional photonic crystal all-optical half adder. The overall dimensions of the structure are very compact, approximately 392 μm2. As can be seen from a comparison of fig. 5 and 11, the half adder is designed to have the characteristic of compensating for scattering loss. It can be calculated from fig. 8, 9 and 10 that the operating frequency band is 1528 and 1540 nm. It can be calculated from fig. 5, 6 and 7 that the contrast of the outputs Sum and Carry are equal to 15.34dB and 8.26dB, respectively, the response time is 0.47ps, and the corresponding data transmission rate is 2.126 Tbps. The method has important significance for the design of the all-optical full adder and can be used for a photonic integrated circuit.
The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.
Claims (9)
1. A two-dimensional photonic crystal half-adder, comprising: the optical waveguide optical fiber comprises a waveguide beam splitter, a connected waveguide, an optical XOR logic gate AND an optical AND logic gate.
2. The two-dimensional photonic crystal half-adder of claim 1 wherein said half-adder is comprised of a two-dimensional photonic crystal comprised of an array of triangular lattice dielectric pillars arranged in air.
3. The two-dimensional photonic crystal half-adder of claim 2 wherein the dielectric pillars of said triangular lattice dielectric pillar array are cylindrical.
4. The two-dimensional photonic crystal half adder according to claim 3 wherein the dielectric pillar radius r of said triangular lattice dielectric pillar array is 0.167a, a being the lattice constant of the photonic crystal.
5. The two-dimensional photonic crystal half-adder of claim 1 wherein said waveguide splitter comprises a straight waveguide, a splitter point defect and a ring coupler.
6. The two-dimensional photonic crystal half-adder of claim 5 wherein said ring coupler has a 3 x 3 two-dimensional photonic crystal dielectric cylinder inside.
7. The two-dimensional photonic crystal half-adder of claim 1, wherein said optical XOR logic gate is comprised of an XOR logic gate point defect, two input ports, one output port and one input output port.
8. The two-dimensional photonic crystal half-adder of claim 1 wherein said optical AND logic gate is comprised of an AND logic gate point defect, two input ports, one output port AND one input output port.
9. The two-dimensional photonic crystal half-adder of claim 1 wherein said connected waveguide is comprised of a connected waveguide point defect and a curved waveguide.
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| GB0206807D0 (en) * | 2002-03-22 | 2002-05-01 | Corning Inc | All-optical gate |
| US20030011775A1 (en) * | 2001-05-15 | 2003-01-16 | Marin Soljacic | Mach-Zehnder interferometer using photonic band gap crystals |
| US20080266639A1 (en) * | 2004-04-30 | 2008-10-30 | Andrea Melloni | Optical Device Based on a Three-Arm Mach-Zehnder Interferometer |
| CN102722062A (en) * | 2012-07-18 | 2012-10-10 | 北京邮电大学 | All-optical exclusive-OR logic gate structure based on photonic crystal waveguide integration |
| TW201544887A (en) * | 2014-05-16 | 2015-12-01 | Univ China Sci & Tech | All-optical logic gate apparatus |
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2020
- 2020-09-25 CN CN202011022774.6A patent/CN112114464A/en active Pending
Patent Citations (5)
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|---|---|---|---|---|
| US20030011775A1 (en) * | 2001-05-15 | 2003-01-16 | Marin Soljacic | Mach-Zehnder interferometer using photonic band gap crystals |
| GB0206807D0 (en) * | 2002-03-22 | 2002-05-01 | Corning Inc | All-optical gate |
| US20080266639A1 (en) * | 2004-04-30 | 2008-10-30 | Andrea Melloni | Optical Device Based on a Three-Arm Mach-Zehnder Interferometer |
| CN102722062A (en) * | 2012-07-18 | 2012-10-10 | 北京邮电大学 | All-optical exclusive-OR logic gate structure based on photonic crystal waveguide integration |
| TW201544887A (en) * | 2014-05-16 | 2015-12-01 | Univ China Sci & Tech | All-optical logic gate apparatus |
Non-Patent Citations (3)
| Title |
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| FARIBORZ PARANDIN等: "Reconfigurable all optical half adder and optical XOR and AND logic gates based on 2D photonic crystals", 《OPTICAL AND QUANTUM ELECTRONICS》 * |
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Application publication date: 20201222 |