阅读说明：本技术 基于法拉第电磁感应定律的传光方向可调的全光二极管 (Light transmission direction adjustable all-optical diode based on Faraday's law of electromagnetic induction ) 是由 刘超 贺凯 汪发美 吕靖薇 刘强 王明吉 李贤丽 苏魏全 刘伟 刘睿骑 于 2019-11-05 设计创作，主要内容包括：本发明涉及一种全光二极管,具体涉及一种基于法拉第电磁感应定律的传光方向可调的全光二极管,全光二极管包括磁光材料和金属纳米线,金属纳米线镶嵌在磁光材料内,一束激光聚焦在金属纳米线的中部,金属纳米线两端接直流电源(DC)的正极和负极。该全光二极管基于法拉第电磁感应定律和表面等离子体共振技术,能够有效调制光源传播方向并且可以将设备半径限制在纳米尺度,为实现传光方向可控的全光二极管提供了理论指导；对拓宽表面等离子体共振的应用领域,提升光二极管工作稳定性具有重要的参考价值。(The invention relates to an all-optical diode, in particular to an all-optical diode with adjustable light transmission direction based on Faraday's law of electromagnetic induction. The all-optical diode is based on Faraday's law of electromagnetic induction and surface plasma resonance technology, can effectively modulate the light source transmission direction and limit the equipment radius to nanometer scale, and provides theoretical guidance for realizing the all-optical diode with controllable light transmission direction; the method has important reference value for widening the application field of surface plasma resonance and improving the working stability of the light-emitting diode.)

1. The utility model provides a pass light direction adjustable all-optical diode based on Faraday's law of electromagnetic induction which characterized in that: the all-optical diode comprises a magneto-optical material (2) and a metal nanowire (1), wherein the metal nanowire (1) is embedded in the magneto-optical material (2), a laser beam is focused on the middle part of the metal nanowire (1), and two ends of the metal nanowire (1) are connected with the anode and the cathode of a direct current power supply.

2. The faraday's law of electromagnetic induction based all-optical diode with adjustable light transmission direction of claim 1, wherein: the medium contacted with the two end faces of the metal nanowire (1) is air.

3. The faraday's law of electromagnetic induction based all-optical diode with adjustable light transmission direction of claim 1, wherein: the radius of the magneto-optical material (2) is not less than twice the radius of the metal nanowire (1).

4. Root of herbaceous plantThe faraday electromagnetic induction law-based all-optical diode with adjustable light transmission direction as claimed in claim 3, wherein: radius R of the metal nanowire (1)₀160nm, radius R of said magneto-optical material (2)₁Is 800 nm.

5. The faraday's law of electromagnetic induction based all-optical diode with adjustable light transmission direction of claim 1, wherein: the value of current I in the metal nanowire (1) is 120mA, and the magnitude of an induced magnetic field B of a contact surface of the metal nanowire (1) and the magneto-optical material (2) is 150mT at the current value.

6. The faraday's law of electromagnetic induction based all-optical diode with adjustable light transmission direction as claimed in any one of claims 1 to 5, wherein: the magneto-optical material (2) is bismuth iron garnet.

7. The faraday's law of electromagnetic induction based all-optical diode with adjustable light transmission direction as claimed in any one of claims 1 to 5, wherein: the metal nanowire (1) is made of gold or silver.

The technical field is as follows:

the invention relates to an all-optical diode, in particular to an all-optical diode with adjustable light transmission direction based on Faraday's law of electromagnetic induction.

Background art:

the most basic device on an integrated photonic circuit is the all-optical diode. Compared with electrons, photons have the characteristics of no static mass, high propagation speed and the like, and relatively speaking, the speed of all-optical diodes for transmitting information is far higher than that of diodes widely applied at present. Therefore, if a photodiode capable of being dynamically modulated can be manufactured, it will have great significance for preparing a complex photon loop in the future. Conventional photodiodes are based primarily on photonic crystal structures, including photonic crystal heterojunctions, photonic crystal waveguides, and photonic crystal fibers, among others. In recent years, many new structures have also been proposed for suppressing light transmission in a certain direction, and for realizing asymmetric light transmission. The optical isolator is a non-reciprocal optical resonance-based optical isolator published in the journal of Nature Photonics in 2011, has a length of only 290 mu m, and makes a great contribution to an integrated photonic circuit. In 2015, a bragg grating shaped like a sandwich structure was used to realize unidirectional transmission of light and obtain high transmission contrast, and the light is almost completely suppressed when propagating in the reverse direction, but the preparation process is extremely complicated and requires the assistance of a special light source. Subsequently, photodiodes based on thermal effects were proposed, but such devices are greatly affected by environmental factors, which are detrimental to the integration of photonic devices.

Although the above-mentioned existing structures can realize the unidirectional propagation of light, the limit of the size reduction of the optical device manufactured by the conventional optical theory is half of the wavelength according to the rayleigh criterion of the conventional optical diffraction theory. Nanophotonics is becoming the focus of attention of the world as an interdisciplinary discipline between microelectronics and nanotechnology. Surface Plasmon Polariton (SPP) and electromagnetic specific media are important branches of nanophotonics. Researches show that the surface plasma optics can effectively break through the diffraction limit and realize the control and the constraint of electromagnetic waves under the sub-wavelength scale.

Researches find that the symmetric transmission of light can be broken by the existence of the magnetic field and the magneto-optical effect. Some optical non-reciprocal devices are made based on the magneto-optical effect considering that magneto-optical (MO) materials have anisotropic relative dielectric constants, but these devices do not find an efficient way to modulate the propagation direction of light. The group of Zhu H et al in 2011 provides a metal array structure with a magneto-optical material as a substrate, so that unidirectional transmission of a light source can be controlled, and the optical isolation phenomenon is caused by the anisotropic dielectric constant of the magneto-optical material. The structure may excite SPPs when the magnetic field is perpendicular to the cross-section of the magneto-optical material, and the same applies to nanowires. When direct current exists, an electric toroidal magnetic field B appears around the nanowire, which can be expressed as

Wherein mu₀The conditions of dielectric constant in vacuum, current value I, induced magnetic field radius R and magnetic field direction perpendicular to any cross section of the magneto-optical cladding provide possibility for magneto-optical effect. Therefore, it is feasible to fabricate a one-way conduction device of a light source at a nanoscale based on faraday's law of electromagnetic induction.

The invention content is as follows:

the invention makes up and improves the defects of the prior art, and provides the all-optical diode based on Faraday's law of electromagnetic induction and surface plasma resonance, which can effectively modulate the propagation direction of a light source and limit the radius of equipment to be in a nanometer scale. The method provides theoretical guidance for realizing the all-optical diode with controllable light transmission direction, and has important reference value for widening the application field of surface plasma resonance and improving the working stability of the light diode.

The technical scheme adopted by the invention is as follows: an all-optical diode with adjustable light transmission direction based on Faraday's law of electromagnetic induction comprises a magneto-optical material and a metal nanowire, wherein the metal nanowire is embedded in the magneto-optical material, a laser beam is focused in the middle of the metal nanowire, and two ends of the metal nanowire are connected with the anode and the cathode of a direct current power supply (DC).

Further, the medium in contact with the two end faces of the metal nanowire is air.

Further, the radius of the magneto-optical material is not less than twice the radius of the metal nanowire.

Further, the radius R of the metal nanowire₀160nm, radius R of the magneto-optical material₁Is 800 nm.

Further, the value of the current I in the metal nanowire is 120mA, and the magnitude of an induced magnetic field B of the contact surface of the metal nanowire and the magneto-optical material at the current value is 150 mT.

Further, the magneto-optical material is Bismuth Iron Garnet (BIG).

Further, the metal nanowire is made of gold or silver with low loss in visible light and near infrared light bands.

Further, in the all-optical diode based on faraday's law of electromagnetic induction, the induced magnetic field causes the magneto-optical material to generate anisotropic relative permittivity.

Further, the relative dielectric constant of anisotropy of magneto-optical materials in the all-optical diode based on the faraday's law of electromagnetic induction can cause the non-uniform excitation of the SPP at the two ends of the nanowire, and induce the light source to generate an asymmetric transmission phenomenon in the two directions of the nanowire.

The invention has the beneficial effects that: provided is an all-optical diode based on Faraday's law of electromagnetic induction and surface plasmon resonance, which can effectively modulate the propagation direction of a light source and can limit the radius of equipment to a nanometer scale. The method provides theoretical guidance for realizing the all-optical diode with controllable light transmission direction, and has important reference value for widening the application field of surface plasma resonance and improving the working stability of the light diode. The main advantages are as follows:

(1) the all-optical diode based on Faraday's law of electromagnetic induction can not only excite SPP at two ends of the nanowire within the working wavelength, but also ensure the magneto-optical activity of magneto-optical materials;

(2) the full-light diode based on Faraday's law of electromagnetic induction can realize the modulation of the light transmission direction of the diode by changing the current direction in the nanowire;

(3) the all-optical diode based on Faraday's law of electromagnetic induction is specifically realized through an SPP related theory, the size of equipment is limited to a nanometer scale, and the miniaturization of a photonic device is realized;

(4) the full-light diode based on the Faraday's law of electromagnetic induction can be realized by the existing manufacturing process, and the manufacturing difficulty is low;

(5) the unidirectional light transmission characteristic of the all-optical diode based on the Faraday's law of electromagnetic induction is less influenced by current values and the shape of a magneto-optical cladding, and the structure has good adaptability to manufacturing errors.

Description of the drawings:

FIG. 1 is a schematic perspective view of a first embodiment;

FIG. 2 is a labeled diagram of the first embodiment;

FIG. 3 is a graph showing the dispersion relation of SPPs in the visible and near-infrared light ranges of an all-optical diode according to one embodiment;

FIG. 4 is a graph of nonreciprocal dispersion of the all-optical diode according to the first embodiment when the nanowire materials are different;

FIG. 5 is a graph of extinction ratios of the all-optical diode according to the first embodiment when the nanowire materials are different;

fig. 6 is a distribution diagram of the electric field intensity of the cross section of the two ends of the metal nanowire when the all-optical diode in the first embodiment is λ 373 nm;

FIG. 7 is a diagram showing a numerical simulation of the electric field distribution | E | of the cross section of the all-optical diode structure according to one embodiment;

FIG. 8 is a graph of extinction ratio versus SPP electric field strength along the surface of a nanowire at different current values in the first example;

the specific implementation mode is as follows: