CN106200023A - Magneto-optic memory technique void fraction wave magnetic conduction surface Fast-wave direction controllable light diode - Google Patents

Abstract

The invention discloses a kind of magneto-optic memory technique void fraction wave magnetic conduction surface Fast-wave direction controllable light diode, it includes a light input end mouth, an optical output port, two magneto-optic material layer, a dielectric layer and two bias magnetic fields；Described optical diode and isolator are made up of two magneto-optic material layer and dielectric layer；The left end of described optical diode and isolator is light input end mouth or optical output port, and its right-hand member is optical output port or light input end mouth；The space of said two magneto-optic memory technique interlayer is dielectric layer；Described magneto-optic material layer is magnetic surface fast wave with the surface of dielectric layer；The bias magnetic field that at said two magneto-optic material layer, setting direction is contrary respectively, and direction is controlled；Described magnetic surface fast wave optical diode is made up of the waveguide of magneto-optic memory technique space.Present configuration is simple, light transmissioning efficiency is high, and volume is little, it is simple to integrated.It is suitable for extensive light path integrated, is with a wide range of applications.

Description

Magneto-optical material gap waveguide magnetic surface fast wave direction controllable photodiode

Technical Field

The invention relates to a magneto-optical material, a magnetic surface wave and a photodiode, in particular to a magneto-optical material gap waveguide photodiode with controllable magnetic surface fast wave direction.

Background

A photodiode and an isolator are optical devices that allow light to travel in only one direction, and are used to prevent unwanted optical feedback. The main element of conventional photodiodes and isolators is a faraday rotator, which employs the faraday effect (magneto-optical effect) as its operating principle. The traditional Faraday isolator consists of three polarizers, a Faraday rotator and an analyzer, and the device has a complex structure and is usually applied to free-space optical systems. For integrated optical circuits, integrated optical devices such as optical fibers or waveguides are non-polarization maintaining systems, which cause loss of polarization angle, and thus are not suitable for faraday isolators.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provides a magneto-optical material gap waveguide magnetic surface fast wave direction controllable photodiode which is simple and effective in structure, high in optical transmission efficiency, small in size and convenient to integrate.

The purpose of the invention is realized by the following technical scheme:

the magneto-optical material gap waveguide magnetic surface fast wave direction controllable photodiode comprises an optical input port, an optical output port, two magneto-optical material layers, a medium layer and two bias magnetic fields; the photodiode and the isolator are composed of two magneto-optical material layers and a medium layer; the left ends of the optical diode and the isolator are an optical input port or an optical output port, and the right ends of the optical diode and the isolator are the optical output port or the optical input port; a gap between the two magneto-optical material layers is a medium layer; the surfaces of the magneto-optical material layer and the medium layer are magnetic surface fast waves; bias magnetic fields with opposite directions are respectively arranged at the two magneto-optical material layers, and the directions are controllable; the magnetic surface fast wave photodiode is composed of magneto-optic material gap waveguides.

The optical diode is a three-layer structure optical waveguide formed by a magneto-optical material layer and a medium layer.

The three-layer structure waveguide is a TE working mode waveguide.

The three-layer structure is a straight waveguide structure.

The magneto-optical material is magneto-optical glass, garnet doped with various rare earth elements or a rare earth-transition metal alloy film material.

The medium layer is made of a material with transparent working wave.

The dielectric layer is vacuum, air, glass, silicon dioxide or plastic with transparent working wave.

The bias magnetic field is generated by an electromagnet or provided by a permanent magnet, the current of the electromagnet is direction controllable current, and the permanent magnet can rotate.

The invention is suitable for large-scale optical path integration and has wide application prospect. Compared with the prior art, the method has the following positive effects.

1. Simple structure and convenient realization.

2. The light transmission efficiency is high.

3. Small volume and convenient integration.

Drawings

FIG. 1 is a diagram of a magneto-optical material gap waveguide fast wave direction controllable photodiode.

In figure 1(a) optical input port 1 optical output port 2 first layer 3 second layer 4 of magneto-optical material 4 medium layer 5 bias field ⊙ H₀(external) bias magnetic fieldThickness w of dielectric layer

Fig. 1 (b): optical output port 1 optical input port 2 first layer of magneto-optical material 3 second layer of magneto-optical material 4 medium layer 5 bias fieldBias magnetic field ⊙ H₀(outer) dielectric layer thickness w

FIG. 2 is a diagram of the working principle of the rightward one-way conduction of a photodiode with controllable magnetic surface direction of the magneto-optical material gap waveguide.

FIG. 3 is a schematic diagram of the leftward unidirectional conduction operation of a magneto-optical material gap waveguide photodiode with controllable magnetic surface fast wave direction.

FIG. 4 is a graph showing the forward and reverse transmission efficiency of a magneto-optical material gap waveguide fast wave direction controllable photodiode as a function of the frequency of the light wave.

FIG. 5 is a graph of forward and reverse transmission efficiency of a magneto-optical material gap waveguide fast wave direction controllable photodiode as a function of frequency of light waves.

FIG. 6 is a graph showing the forward and reverse transmission efficiency of a magneto-optical material gap waveguide fast wave direction controllable photodiode as a function of the frequency of the light wave.

Detailed Description

As shown in figure 1, the magneto-optical material gap waveguide photodiode with controllable magnetic surface fast wave direction comprises an optical input port 1, an optical output port 2, a first magneto-optical material layer 3, a second magneto-optical material layer 4, a medium layer 5 and two bias static magnetic fields, wherein the photodiode and an isolator are formed by the first magneto-optical material layer 3, the first magneto-optical material layer 4 and the medium layer 5, the magneto-optical material diode with controllable magnetic surface fast wave is formed by the magneto-optical material gap waveguide, the first magneto-optical material layer 3, the second magneto-optical material layer 4 and the medium layer 5 form a three-layer structured optical waveguide capable of unidirectionally transmitting optical signals, namely the photodiode, the three-layer structure is a straight waveguide structure, the waveguide is a TE working mode waveguide, a gap between the first magneto-optical material layer 3 and the second magneto-optical material layer 4 is the medium layer 5, the medium layer 5 is a region mainly concentrated by optical energy, the medium layer 5 can be made of working wave transparent material, can also be made of vacuum, air, glass, silica or working wave transparent plastic, preferably air or glass, the magneto-optical material layer is made of glass, the transition metal materials with controllable magnetic field of the first magneto-optical material, the second magneto-optical material, the rare earth bias magnetic field bias magnetic material layer ⊙, and the second magneto-optical material, and the magnetic field bias metal₀(external) and bias magnetic fieldExternal magnetic field H₀Generated by an electromagnet whose direction of current flow is controllable or provided by a rotatable permanent magnet, the direction of current flow can be controlled to change the conduction direction of the photodiode, or by rotating the permanent magnet. Bias fields H for the first layer 3 and the second layer 4 in opposite directions₀Under the action of the magnetic-optical material layer 3, the static magnetic field H which is perpendicular to the paper surface and is outwards applied is adjusted₀And the magneto-optical material layer 4 is applied with a static magnetic field H perpendicular to the paper surface and facing inwards₀Meanwhile, the port 1 of the photodiode and the isolator is an optical input port, and the port 2 is an optical output port; otherwise, the first magneto-optical material layer is modulated3 external static magnetic field H perpendicular to paper surface₀And the second layer 4 of magneto-optical material applies a static magnetic field H directed perpendicularly to the plane of the paper₀When the optical diode and the isolator are connected, the port 2 is an optical input port, and the port 1 is an optical output port.

The surface magnetic wave generated at the magneto-optical material-medium interface is a phenomenon similar to metal Surface Plasmon Polariton (SPP). Under the action of a bias magnetic field, the magnetic conductivity of the magneto-optical material is in a tensor form, and meanwhile, the effective refractive index of the magneto-optical material is a negative value within a certain optical band range. Thus, the surface of the magneto-optical material can generate a guided wave and has the property of propagating in one direction, called a magnetic surface wave (surface magnetically polarized wavelet, SMP).

The invention relates to a magneto-optical material gap waveguide photodiode with controllable magnetic surface fast wave direction, which has a three-layer structure of magneto-optical material-medium-magneto-optical material, wherein the magneto-optical material-medium interface generates magnetic surface fast waves to perform unidirectional light transmission, and the current direction controllable electromagnet is used for controlling the conduction direction of the photodiode.

The technical scheme of the invention is based on the optical nonreciprocal property of the magneto-optical material and the unique conductive surface wave characteristic of the magneto-optical material-medium interface, and realizes the design of the optical diode and the isolator. The basic principle of the technical scheme is as follows:

the magneto-optical material is a material with magnetic anisotropy, and magnetic dipoles in the magneto-optical material are arranged in the same direction due to an external magnetic field, so that a magnetic dipole moment is generated. The magnetic dipole moment will interact strongly with the optical signal, resulting in a non-reciprocal transmission of light. A bias magnetic field H in a direction perpendicular to the paper surface₀The permeability tensor of the magneto-optical material is:

$\[{\mathrm{\μ}}_1\]=\left(\begin{array}{ccc}{\mathrm{\μ}}_r& {\mathrm{i\μ}}_{\mathrm{\κ}}& 0\\ -{\mathrm{i\μ}}_{\mathrm{\κ}}& {\mathrm{\μ}}_r& 0\\ 0& 0& {\mathrm{\μ}}_0\end{array}\right),---\left(1\right)$

the elements of the permeability tensor are given by the following system of equations:

${\mathrm{\μ}}_r={\mathrm{\μ}}_0(1+\frac{{\mathrm{\ω}}_m({\mathrm{\ω}}_0-i\mathrm{\α}\mathrm{\ω})}{{({\mathrm{\ω}}_0-i\mathrm{\α}\mathrm{\ω})}^2-{\mathrm{\ω}}^2}),{\mathrm{\μ}}_{\mathrm{\κ}}={\mathrm{\μ}}_0\frac{{\mathrm{\ω}}_m\mathrm{\ω}}{{({\mathrm{\ω}}_0-i\mathrm{\α}\mathrm{\ω})}^2-{\mathrm{\ω}}^2},{\mathrm{\ω}}_0={\mathrm{\μ}}_0{\mathrm{\γH}}_0,{\mathrm{\ω}}_m={\mathrm{\μ}}_0{\mathrm{\γM}}_s,---\left(2\right)$

wherein, mu₀Is magnetic permeability in vacuum, gamma is gyromagnetic ratio, H₀For application of a magnetic field, M_sTo saturation magnetization, ω is the operating frequency and α is the loss factor, H if the direction of the bias field is changed to be perpendicular to the paper, then H₀And M_sThe sign will change.

The surface magnetic wave generated at the magneto-optical material-medium interface can be solved according to the permeability tensor of the magneto-optical material and the Maxwell equation set. The electric field and the magnetic field existing at the interface of the surface wave (TE wave) should have the following forms:

$E_i=\left(\begin{array}{c}{e}_{xi}\\ 0\\ 0\end{array}\right)e^{i(k_{z}z+k_{yi}y-\mathrm{\ω}t)},H_i=\left(\begin{array}{c}0\\ h_{yi}\\ h_{zi}\end{array}\right)e^{i(k_{z}z+k_{yi}y-\mathrm{\ω}t)}---\left(3\right)$

where i-1 represents the region of magneto-optical material and i-2 represents the region of the medium. Substituting maxwell's equations:

$\▿\×E_i=-j\frac{\∂E_{xi}}{\∂z}-k\frac{\∂E_{xi}}{\∂y}=-\frac{\∂B_i}{\∂t},\▿\×H_i=-\frac{\∂D_i}{\∂t},---\left(4\right)$

then, based on the constitutive relation and the boundary condition, the wave vector k of the magnetic surface wave can be obtained_zTranscendental equation of (a):

$\frac{{\mathrm{\μ}}_e}{{\mathrm{\μ}}_0}\sqrt{{\mathrm{\ω}}^2{\mathrm{\μ}}_0{\mathrm{\ϵ}}_0-k_z^2}+\sqrt{{\mathrm{\ω}}^2{\mathrm{\μ}}_e{\mathrm{\ϵ}}_1-k_z^2}-\frac{{\mathrm{j\μ}}_k}{{\mathrm{\μ}}_r}{k}_z=0,---\left(5\right)$

wherein,is the effective permeability of the magneto-optical material. The transcendental equation can be solved by numerical solution to finally obtain k_zThe value of (c). It can also be seen from the equation that since the equation contains μ_κk_zTherefore, the magnetic surface wave has nonreciprocity (unidirectional propagation). From the solution of the equation, it can be concluded that when the magnetic field is changed to the opposite direction, the conduction direction of the photodiode also changes to the opposite direction.

It can be seen that if a three-layer structure of magneto-optical material-medium-magneto-optical material is adopted, and magnetic fields in opposite directions are added at the first magneto-optical material layer 3 and the second magneto-optical material layer 4, and the direction of the magnetic field of the electromagnet is controlled by current, an effective direction-controllable photodiode is formed. As shown in FIG. 2, Yttrium Iron Garnet (YIG) is used as the magnetic anisotropic material, and the medium layer is air (n)₀1) with a bias field of 900Oe, a dielectric layer 5 with a thickness w of 5mm, and a device operating frequency f determined by the dielectric constants of the magneto-optical material and the medium₁，₂And magnetic permeability [ mu ]₁]，μ₂The determined working frequency is 6GHz, and the YIG material loss coefficient α is 3 × 10^-4. The direction of the magnetic field at the first magneto-optical material layer 3 is directed perpendicularly out of the plane of the paper and the direction of the magnetic field at the second magneto-optical material layer 4 is directed perpendicularly into the plane of the paper, when light is input from the port 1, at both magneto-optical material-medium boundariesGenerating a magnetic surface wave with unidirectional forward transmission on the surface, and finally outputting the magnetic surface wave from a port 2, namely, conducting the directional controllable photodiode to the right in a unidirectional way; when light is input from port 2, the light wave cannot be transmitted backward inside the device due to the non-reciprocity of the magnetic surface wave and thus cannot be output from port 1, and the light energy is blocked at port 2. The turn-on direction of the photodiode is determined by the direction of the applied magnetic field, and when the direction of the magnetic field applied by the first magneto-optical material layer 3 and the second magneto-optical material layer 4 is changed simultaneously, as shown in fig. 3, Yttrium Iron Garnet (YIG) is used as the magnetic anisotropic material, and the medium layer is air (n)₀1) with a bias field of 900Oe, a dielectric layer 5 with a thickness w of 5mm, and a device operating frequency f determined by the dielectric constants of the magneto-optical material and the medium₁，₂And magnetic permeability [ mu ]₁]，μ₂The determined working frequency is 6GHz, and the YIG material loss coefficient α is 3 × 10^-4. The magnetic field at the first magneto-optical material layer 3 is directed into the page and the magnetic field at the second magneto-optical material layer 4 is directed out of the page, the diode conduction direction being opposite. When light waves are input from the port 1, the inside of the device cannot transmit reverse light waves due to the non-reciprocity of the device, the port 2 does not have any light output, and all light energy is blocked at the port 1; when light waves are input from the port 2, magnetic surface waves can be generated inside the device and then output from the port 1, namely, the left one-way conduction of the direction-controllable photodiode.

The magneto-optical material gap waveguide direction controllable photodiode of the device has a three-layer structure characteristic of magneto-optical material-medium-magneto-optical material, the whole device is of a straight structure, the sizes of a first magneto-optical material layer and a second magneto-optical material layer and the thickness w of a medium layer 5 can be flexibly selected according to working wavelength and actual requirements, the change of the sizes does not greatly influence the performance of the device, three embodiments are provided by combining the attached drawings, Yttrium Iron Garnet (YIG) is adopted as a magnetic anisotropy material in the embodiments, a bias magnetic field is generated by an electromagnet with controllable current direction, the size is 900Oe, the direction determines the conduction direction of the diode, the thickness w of the medium layer 5, and the loss coefficient α of the YIG material is 353 3 × 10^-4The operating frequency f of the device is set byDielectric constant of magneto-optical material and medium₁，₂And magnetic permeability [ mu ]₁]，μ₂And (4) determining.

Example 1

Referring to fig. 1(a) and (b), the magneto-optical material gap waveguide forms a magnetic surface fast wave direction controllable photodiode, and the medium layer 5 is air (n)₀1) with a thickness w of 5 mm. In the working frequency range, the direction of a magnetic field at the position 3 is controlled to be vertical to the paper surface outwards through the electromagnet current, the direction of the magnetic field at the position 4 is controlled to be vertical to the paper surface inwards, and the photodiode is conducted from a port to a port 2; conversely, controlling the direction of the magnetic field at 3 to go inside the page and the direction of the magnetic field at 4 to go outside the page, the photodiode will conduct from port 2 to port 1. The forward and reverse transmission efficiency is the same for both cases. Referring to fig. 4, the operating frequency range of the photodiode and the isolator of the straight waveguide structure is 5.02GHz to 7.36 GHz. In the working frequency range, the maximum forward and reverse transmission isolation of the photodiode and the isolator is 35.3991dB and the forward transmission insertion loss is 0.0016dB by considering material loss.

Example 2

Referring to fig. 1(a) and (b), the magneto-optical material gap waveguide forms a magnetic surface fast wave direction controllable photodiode, and the medium layer 5 is air (n)₀1) with a thickness w of 7 mm. In the working frequency band, the direction of a magnetic field at the first magneto-optical material layer 3 is controlled to be vertical to the paper surface and outwards through the electromagnet current, the direction of the magnetic field at the second magneto-optical material layer 4 is controlled to be vertical to the paper surface and inwards, and the photodiode is conducted from a port 1 to a port 2; conversely, by controlling the direction of the magnetic field at the first magneto-optical material layer 3 perpendicular to the plane of the paper and the direction of the magnetic field at the second magneto-optical material layer 4 perpendicular to the plane of the paper, the photodiode will conduct from port 2 to port 1. The forward and reverse transmission efficiency is the same for both cases. Referring to fig. 5, the operating frequency range of the photodiode and the isolator of the straight waveguide structure is 5.00GHz to 7.36 GHz. In the operating frequency range, taking into account material losses, photodiodes andthe highest forward and reverse transmission isolation degree of the isolator is 35.5104dB, and the forward transmission insertion loss is 0.0014 dB.

Example 3

Referring to fig. 1(a) and (b), the magneto-optical material gap waveguide forms a magnetic surface fast wave direction controllable photodiode, and the medium layer 5 is glass (n)₀1.5) and its thickness w is 5 mm. In the working frequency band, the direction of a magnetic field at the first magneto-optical material layer 3 is controlled to be vertical to the paper surface and outwards through the electromagnet current, the direction of the magnetic field at the second magneto-optical material layer 4 is controlled to be vertical to the paper surface and inwards, and the photodiode is conducted from a port 1 to a port 2; conversely, by controlling the direction of the magnetic field at the first magneto-optical material layer 3 perpendicular to the plane of the paper and the direction of the magnetic field at the second magneto-optical material layer 4 perpendicular to the plane of the paper, the photodiode will conduct from port 2 to port 1. The forward and reverse transmission efficiency is the same for both cases. Referring to fig. 6, the operating frequency range of the photodiode and the isolator of the straight waveguide structure is 4.94GHz to 7.78 GHz. In the working frequency range, the photodiode and the isolator can reach the highest forward and reverse transmission isolation degree of 39.9206dB and the forward transmission insertion loss of 0.0007dB by considering the material loss.

The optical frequency range of the magnetic surface fast wave transmitted by the magneto-optical material gap waveguide, that is, the operating frequency range of the direction controllable optical diode, can be obtained from the transmission efficiency curve diagrams of the magneto-optical material gap waveguide magnetic surface fast wave direction controllable optical diode with different parameters in fig. 4, fig. 5 and fig. 6. From the results, the magneto-optical material gap waveguide magnetic surface fast wave direction controllable photodiode can work effectively.

The invention described above is subject to modifications both in the specific embodiments and in the field of application and should not be understood as being limited thereto.

Claims (8)

1. A magneto-optical material gap waveguide magnetic surface fast wave direction controllable photodiode is characterized in that: the optical fiber comprises an optical input port, an optical output port, two magneto-optical material layers, a medium layer and two bias magnetic fields; the photodiode and the isolator are composed of two magneto-optical material layers and a medium layer; the left ends of the optical diode and the isolator are an optical input port or an optical output port, and the right ends of the optical diode and the isolator are the optical output port or the optical input port; a gap between the two magneto-optical material layers is a medium layer; the surfaces of the magneto-optical material layer and the medium layer are magnetic surface fast waves; bias magnetic fields with opposite directions are respectively arranged at the two magneto-optical material layers, and the directions are controllable; the magnetic surface fast wave photodiode is composed of magneto-optic material gap waveguides.

2. A magneto-optical material gap waveguide magnetic surface fast wave direction controllable photodiode according to claim 1, characterized in that: the optical diode is a three-layer structure optical waveguide formed by a magneto-optical material layer and a medium layer.

3. A magneto-optical material gap waveguide magnetic surface fast wave direction controllable photodiode according to claim 1, characterized in that: the three-layer structure waveguide is a TE working mode waveguide.

4. A magneto-optical material gap waveguide magnetic surface fast wave direction controllable photodiode according to claim 2 or 3, characterized in that: the three-layer structure is a straight waveguide structure.

5. A magneto-optical material gap waveguide magnetic surface fast wave direction controllable photodiode according to claim 1, characterized in that: the magneto-optical material is magneto-optical glass, garnet doped with various rare earth elements or a rare earth-transition metal alloy film material.

6. A magneto-optical material gap waveguide magnetic surface fast wave direction controllable photodiode according to claim 1, characterized in that: the medium layer is made of a material with transparent working wave.

7. A magneto-optical material gap waveguide magnetic surface fast wave direction controllable photodiode according to claim 1, characterized in that: the dielectric layer is vacuum, air, silicon dioxide or plastic with transparent working wave.

8. A magneto-optical material gap waveguide magnetic surface fast wave direction controllable photodiode according to claim 1, characterized in that: the bias magnetic field is generated by an electromagnet or provided by a permanent magnet, the current of the electromagnet is direction controllable current, and the permanent magnet can rotate.