WO2016050183A1

WO2016050183A1 - Compensation-column-introduced three-port optical circulator having high transmission rate and isolation

Info

Publication number: WO2016050183A1
Application number: PCT/CN2015/090882
Authority: WO
Inventors: 欧阳征标; 王琼
Original assignee: 深圳大学; 欧阳征标
Priority date: 2014-09-29
Filing date: 2015-09-28
Publication date: 2016-04-07
Also published as: CN104597630B; CN104597630A

Abstract

A compensation-column-introduced three-port optical circulator having high transmission rate and isolation. The three-port optical circulator comprises three photonic crystal cross waveguides corresponding to three ports (11, 12, 13) respectively, wherein the three ports (11, 12, 13) are distributed on the periphery of a photonic crystal. A second dielectric material column (02) is arranged at the cross part of the central axes of the three photonic crystal waveguides. Three identical magneto-optic material columns (A, B, C) are arranged on the most adjacent parts of the second dielectric material column (02) and distributed on the periphery of the cross center of the three cross waveguides in a 120-degree-angle rotation symmetric mode. Three identical third dielectric material columns (03), namely, compensation columns, are arranged on the secondary adjacent parts of the second dielectric material column. The three compensation columns are distributed on the periphery of the cross center of the three cross waveguides in a 120-degree-angle rotation symmetric mode. An electromagnetic wave signal is input from the port of any waveguide and output from the port of the next adjacent waveguide, and another port is in an isolated state to form one-way circular transmission. Therefore, the three-port optical circulator is compact in structure and facilitates the integration of other photonic crystal devices.

Description

High-rate and high-isolation three-port optical circulator with compensation column

Technical field

The invention belongs to the technical field of photonic crystal circulators, and in particular relates to a three-port photonic crystal circulator with a plurality of columns of magneto-optical materials coupled to a compensation column.

Background technique

With the rapid development of all-optical information processing technology, compact and easy to integrate photonic crystal devices have received extensive attention and research in large-scale integrated optical path systems. A photonic crystal is a micro-material in which the dielectric constant or magnetic permeability is arranged in a periodic or quasi-periodic manner in space, which can make electromagnetic waves in a certain frequency band not propagate therein, thereby forming a photonic band gap. To date, various micro-devices based on photonic crystals have been developed and developed, such as high-Q microcavities, fiber optic detectors, microwave filters, high-efficiency lasers, and micro-sensors. Photonic crystals are hailed as one of the most promising photonic devices for all-optical integrated chips. The successful realization of a photonic crystal logic integrated optical path like a large-scale integrated circuit will enable all-optical information technology to leap to a new level in terms of processing speed, transmission quality, and storage capacity.

In the optical path, the increase in integration leads to a significant increase in signal interference between components, and signal interference greatly affects the performance of each component, and may even cause the entire system to be abnormal. Therefore, eliminating signal interference and ensuring transmission stability have become the primary problem to improve optical path integration.

The realization of a magneto-optical circulator in a photonic crystal structure is a relatively new field of research. In 2005, it was first proposed by the S.Fan research team at Stanford University. So far, several photonic crystal magneto-optical circulators have been studied, but most of them are based on dielectric substrate-air column type structure. For another kind of air substrate-medium column type photonic crystal magneto-optical circulator research less. Therefore, there are still many technical problems to be solved in the research of photonic crystal magneto-optical circulators, especially: how to effectively develop the air substrate-media column type circulator in terms of device type; how to obtain compact structure and form in terms of device structure Concise circulator; how to achieve high isolation and high transmission rate circulator in terms of device performance. The solution of the above technical problems will inevitably provide new ideas and development directions for the research of photonic crystal magneto-optical circulators.

Summary of the invention

The object of the present invention is to overcome the deficiencies in the prior art and to provide a circulator with a single-directional loop function that is compact, easy to integrate, has high isolation, and high transmission rate.

The object of the present invention is achieved by the following technical solutions.

The three-port circulator of the present invention comprises a two-dimensional photonic crystal of a first dielectric material column arranged in a triangular lattice array in a low refractive index background medium, each of the first dielectric material columns occupying a lattice of the triangular lattice, The invention comprises three photonic crystal cross-waveguides and three ports, wherein the three photonic crystal cross-waveguides are three photonic crystal waveguides which are cross-connected and have an angle of 120° between the two, and the three photonic crystal cross-waveguides respectively correspond to Three ports, three ports respectively distributed on the peripheral end faces of the photonic crystal; a second dielectric material column is disposed at the intersection of the central axes of the three photonic crystal waveguides, and three are respectively disposed adjacent to the second dielectric material column The same magneto-optical material column; the three magneto-optical material columns at an angle of 120° Rotating symmetrically around the intersection centers of the three crossed waveguides, and each magneto-optical material column is located on the central axis of the waveguide in which it is located; three identical segments are respectively disposed in the second adjacent portion of the second dielectric material column a column of three dielectric materials; the column of the third dielectric material is a compensation column; the three compensation columns are rotationally symmetrically distributed around the intersection center of the three intersecting waveguides at an angle of 120°, and each compensation column is located at a waveguide of the same On the central axis, the electromagnetic wave signal is input from any one of the waveguide ports, and will be output from the next adjacent waveguide port, and the other port is isolated to form a unidirectional circular transmission.

The low refractive index background medium is air, vacuum, silica, magnesium fluoride, or a dielectric material having a refractive index of less than 1.5.

The first dielectric material column is a silicon material, gallium arsenide, titanium dioxide, gallium nitride, or a dielectric material having a refractive index greater than 2.

The first dielectric material column has a circular, square, or regular polygonal cross section, and the first dielectric material column preferably has a circular cross-sectional shape.

The photonic crystal waveguide removes a plurality of first dielectric material columns from the central position of the photonic crystal at an angle of 60° horizontally, 180° to the horizontal, and 300° to the horizontal, and is located at 60°. The first dielectric material column outside the 180° outer direction is shifted outward by a distance b along the 120° axis, and the first dielectric material column outside the 180° and 300° direction is totally shifted outward by a distance b along the 240° axis. Forming the three cross-connected photonic crystal waveguides by shifting the entire first dielectric material column outside the range between 300° and 60° by 0° in the right axis.

The second dielectric material column is a silicon material, gallium arsenide, titanium dioxide, gallium nitride, or a dielectric material having a refractive index greater than 2; the second dielectric material column has an equilateral triangle in cross section, and a middle portion and three top portions The lines are at an angle of 60° to the horizontal, 180° to the horizontal, and 300° to the horizontal.

The three magneto-optical material columns are respectively ferrite materials and have a circular cross section.

The third dielectric material column is a silicon material, gallium arsenide, titanium dioxide, gallium nitride, or a dielectric material having a refractive index greater than 2.

The cross section of the third dielectric material column is an equilateral triangle, a circle, or a regular polygon, and the cross section shape of the third dielectric material column is preferably an equilateral triangle, and one top of the equilateral triangle corresponds to the photonic crystal waveguide The direction of the central axis, and the top corresponds to the direction of the waveguide port.

The photonic crystal circulator of the present invention is widely applicable to any electromagnetic wave band, such as a microwave band, a millimeter wave band, a terahertz band, an infrared band, or a visible light band. Compared with the prior art, the present invention has the following positive effects.

1. Using the non-reciprocal characteristics of the magneto-optical material to fabricate the optical circulator, the single-directional loop function of the signal between the transmission ports in the optical device can be obtained, which can effectively prevent signal reflow, eliminate crosstalk between signals, and ensure the normal operation of the optical path system. The magneto-optical circulator is an indispensable function optimization device in the integrated optical path.

.2. The use of compensation column in photonic crystal can improve the performance of multiple coupled magneto-optical material columns, non-reciprocal transmission effect, design a compact, easy to integrate, and Integration with other photonic crystal devices enables single-directional optical ring transmission of signals between three ports in the device.

3. Using the compensation column to achieve effective matching of the magneto-optical material column with the corresponding photonic crystal waveguide, and obtain the performance of the three-port photonic crystal magneto-optical circulator with high transmission efficiency and high isolation, and provide excellent anti-signal reflow for the photonic crystal integrated optical path system. The need for circulators to eliminate signal interference.

DRAWINGS

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

FIG. 1 is a schematic structural view of a three-port optical circulator with high transmission rate and high isolation introduced into a compensation column according to the present invention.

In the figure: air background 00 first dielectric material column 01 second dielectric material column 02 third dielectric material column 03 magneto-optical material column A magneto-optical material column B magneto-optical material column C first waveguide port 11 second waveguide port 12 Three waveguide port 13 waveguide width w

2 is a diagram showing the isolation and insertion loss of a three-port optical circulator with high transmission rate and high isolation introduced into a compensation column according to the present invention.

FIG. 3 is a schematic diagram of a first transmission effect of a three-port optical circulator with high transmission rate and high isolation introduced into a compensation column according to the present invention.

FIG. 4 is a schematic diagram of a second transmission effect of a three-port optical circulator with high transmission rate and high isolation introduced into a compensation column according to the present invention.

FIG. 5 is a schematic diagram of a third transmission effect of a three-port optical circulator with high transmission rate and high isolation introduced into a compensation column according to the present invention.

detailed description

As shown in FIG. 1, the present invention introduces a high-rate and high-isolation three-port optical circulator of a compensation column, including a low refractive index background medium, which is an air background 00 and an air background 00. a two-dimensional photonic crystal of the first dielectric material column 01 arranged by the triangular lattice array, each of the first dielectric material columns 01 occupies one lattice of the triangular lattice, and the lattice constant a of the photonic crystal is selected to be 10.0 mm. The first dielectric material column 01 is made of a silicon material having a refractive index of 3.4, a cross-sectional shape of a circular shape, and a radius of r ₁ = 2.0 mm. In the photonic crystal, three photonic crystal waveguides are cross-connected and have an angle of 120° between the two, and the photonic crystal waveguides are at an angle of 60° with respect to the horizontal, starting from the center position of the photonic crystal. A plurality of first dielectric material columns 01 are removed in an angular direction of 180° and at an angle of 300° to the horizontal direction, and the first dielectric material column 01 located outside between 60° and 180° is shifted outwardly along the 120° axis. The distance b, the first dielectric material column 01 located outside the 180° and 300° is totally shifted outward by a distance b along the 240° axis, and the first dielectric material column 01 located outside between 300° and 60° is along the whole 0° axial right translation distance b (where

a is the lattice constant of the photonic crystal), which constitutes three intersections and is rotationally symmetrically distributed at an angle of 120° and the width w is

Photonic crystal waveguide. The length of the three photonic crystal waveguides is na, and the width is adjusted to

a is the lattice constant of the photonic crystal, and n is an integer of 4 or more.

Introducing a second dielectric material column 02 for guiding at the intersection of the central axes of the three photonic crystal waveguides, that is, at the center of the photonic crystal, the second dielectric material column 02 is made of silicon material, and its refractive index For 3.4, the cross-sectional shape uses an equilateral triangle. The line connecting the center and the three vertices is at an angle of 60° with respect to the horizontal, an angle of 180° with the horizontal, and an angle of 300° with the horizontal. In the vicinity of the second dielectric material column 02, respectively, along the central axis of the three photonic crystal waveguides, that is, in the angular direction of 60° with the horizontal, the angular direction of 180° with the horizontal, and the angle of 300° with the horizontal, respectively. A column of the same magneto-optical material A, B and C is introduced thereon, and the three magneto-optical material columns A, B and C are respectively rotationally symmetrically distributed around the intersection center of the three intersecting waveguides at an angle of 120°, and each magnetic The column of optical material is located on the central axis of the waveguide on which it is located, and the center of each column of magneto-optical material (A, B or C) and the center of the second column of dielectric material 02 are both 0.67a, ie 6.7 mm. The magneto-optical material columns A, B and C respectively adopt a ferrite material, and the cross-sectional shape thereof is circular, the dielectric constant is 12.9, and the magnetic permeability tensor is:

Where κ = ω _m ω / (ω ₀ ² - ω ² ), μ _r =1 + κω ₀ / ω, ω ₀ = μ ₀ γH ₀ , ω _m = μ ₀ γM _s , γ = 1.759 × 10 ¹¹ C/ Kg, M _s = 2.39 × 10 ⁵ A/m. The magnetic field applied to the magneto-optical material columns A, B and C was H ₀ = 3.45 × 10 ⁵ A/m. Introducing a same third dielectric material column 03 along the central axis direction of the three photonic crystal waveguides in the second vicinity of the second dielectric material column 02, that is, the third dielectric material column is a compensation column, and the third dielectric material The pillar 03 is made of a silicon material having a refractive index of 3.4, and the cross-sectional shape adopts an equilateral triangle, and one vertex of the equilateral triangle corresponds to the central axis direction of the photonic crystal waveguide, and the vertex corresponds to the waveguide port direction. The three compensating columns are rotationally symmetrically distributed around the intersection of the three intersecting waveguides at an angle of 120°, and each compensating post is located on the central axis of the waveguide on which it is located. The center distance of the center of each of the third dielectric material columns 03 and the second dielectric material column 02 is 1.3a, that is, 13 mm.

The photonic crystal circulator that introduces the compensation column includes three waveguide ports, which are a first waveguide port 11, a second waveguide port 12, and a third waveguide port 13, respectively, and the three waveguide ports respectively correspond to three photonic crystal cross-waveguides The three waveguide ports are respectively distributed on the peripheral end faces of the photonic crystal.

Further, the structural parameters of the photonic crystal circulator that introduces the compensation column are optimized: the electromagnetic wave signal is set to be incident from the first waveguide port 11, and the corresponding waveguide port is detected at the second waveguide port 12 and the third waveguide port 13, respectively. The electromagnetic wave signal power, and the insertion loss of the second waveguide port 12 is set to 10 log (P _input / P _output ), and the isolation of the third waveguide port 13 is 10 log (P _input / P _isolation ), wherein P _input , P _output The _{isolation from} P is the input port, that is, the signal power detected by the first waveguide port 11, and the output port, that is, the signal power detected by the second waveguide port 12 and the isolated port, that is, the signal power detected by the third port 13. By optimizing the length of the equilateral triangle of the second dielectric material column 02 to be 2.7 mm, the length of the equilateral triangle of the third dielectric material column 03 is 2.0 mm, and the cylindrical radii of the magneto-optical material columns A, B and C are respectively 2.55 mm. The insertion loss and isolation calculation curve of the three-port photonic crystal circulator is shown in Fig. 2. In FIG. 2, the solid line and the broken line represent the insertion loss of the second waveguide port 12 and the isolation of the third waveguide port 13 at different frequencies, respectively. Figure 2 shows that the photonic crystal circulator operates at a frequency of 10.58 GHz to 10.68 GHz, the insertion loss of the second waveguide port 12 in this band is as low as 0.022 dB, and the isolation of the third waveguide port 13 is as high as 23.4 dB.

Due to the structural rotational symmetry, the above structural parameter optimization is also applicable to the electromagnetic wave signal being input from the second waveguide port 12, outputted from the third waveguide port 13, or input from the third waveguide port 13, and outputted from the first waveguide port 11 In the case, the function calculation curve for obtaining the circulator is the same as that of Fig. 2.

Verify the performance of the three-port photonic crystal circulator based on the above optimization results:

Referring to FIG. 3, an electromagnetic wave of any frequency in the frequency range of 10.58 GHz to 10.68 GHz is used. For example, an electromagnetic wave having a frequency of 10.62 GHz is incident from the first waveguide port 11, and the magneto-optical material columns A and B respectively perform a 60-degree angular rotation on the electromagnetic wave. Finally, the electromagnetic wave is output from the second waveguide port 12, and the insertion loss of the second waveguide port 12 is 0.022 dB. The second dielectric material column 02 in the photonic crystal directs the magneto-optical material columns A and B to be effectively coupled. The third waveguide port 13 is in an optically isolated state in which the magneto-optical material column C has a signal isolation effect on the third waveguide port 13, and the isolation of the third waveguide port 13 is 23.4 dB. The third dielectric material column 03 serves to compensate for the mismatch between the magneto-optical material column A and the magneto-optical material column B and the corresponding waveguide, so that the transmission efficiency of the signal from the waveguide port 11 to the waveguide port 12 can be effectively improved.

Referring to FIG. 4, an electromagnetic wave having a frequency of 10.62 GHz is incident from the second waveguide port 12, and the magneto-optical material columns B and C respectively rotate the electromagnetic wave at an angle of 60°, and finally the electromagnetic wave is output from the third waveguide port 13, and the third waveguide port The insertion loss of 13 is 0.022 dB. The second dielectric material column 02 in the photonic crystal directs the magneto-optical material columns B and C to be effectively coupled. The first waveguide port 11 is in an optically isolated state, wherein the magneto-optical material column A has a signal isolation effect on the first waveguide port 11, the first waveguide port 11 The isolation is 23.4dB. The third dielectric material column 03 serves to compensate for the mismatch between the magneto-optical material column B and the magneto-optical material column C and the corresponding waveguide, so that the transmission efficiency of the signal from the waveguide port 12 to the waveguide port 13 can be effectively improved.

Referring to FIG. 5, an electromagnetic wave having a frequency of 10.62 GHz is incident from the third waveguide port 13, and the magneto-optical material columns C and A respectively rotate the electromagnetic wave at an angle of 60°, and finally the electromagnetic wave is output from the first waveguide port 11, the first waveguide port. The insertion loss of 11 is 0.022 dB. The second dielectric material column 02 in the photonic crystal directs the magneto-optical material columns C and A to be effectively coupled. The second waveguide port 12 is in an optically isolated state, wherein the magneto-optical material column B has a signal isolation effect on the second waveguide port 12, and the second waveguide port 12 has an isolation of 23.4 dB. The third dielectric material column 03 serves to compensate for the mismatch between the magneto-optical material column C and the magneto-optical material column A and the corresponding waveguide, so that the transmission efficiency of the signal from the waveguide port 13 to the waveguide port 11 can be effectively improved.

The electromagnetic wave signal input from any one of the waveguide ports in the photonic crystal three-port magneto-optical circulator will be outputted from the next adjacent waveguide port in a counterclockwise direction, and the other of the three ports is an isolated electromagnetic wave signal port, that is, three ports are realized. One-way optical ring transmission function.

The photonic crystal three-port circulator of the present invention is not limited to the above-described embodiments, as the technical solutions disclosed by those skilled in the art according to the present invention, and according to the principle of proportional scaling of photonic crystals and the selection of corresponding materials, photonic crystals and the like. The scaling principle is: the relationship between the operating wavelength of the circulator and the photonic crystal lattice constant, the size of the first dielectric material column in the photonic crystal, the size of the second dielectric material column, and the size of the magneto-optical material column. The positive proportional relationship, that is, the above parameters are expanded or reduced by e times, and the operating wavelength of the circulator is also expanded or reduced by e times.

The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. Within the scope.

Claims

A high-rate and high-isolation three-port optical circulator incorporating a compensation column, comprising a two-dimensional photonic crystal of a first dielectric material column arranged in a triangular lattice array in a low refractive index background medium, each A dielectric material column occupies a lattice of a triangular lattice, and is characterized by further comprising three photonic crystal cross-waveguides and three ports, the three photonic crystal cross-waveguides having three cross-connections and an angle between the two a 120° photonic crystal waveguide, the three photonic crystal cross-waveguides respectively corresponding to three ports, three ports respectively distributed on the peripheral end faces of the photonic crystals; and a second medium disposed at the intersection of the central axes of the three photonic crystal waveguides a column of material, three identical magneto-optical material columns are respectively disposed at the nearest portion of the second dielectric material column; the three magneto-optical material columns are rotationally symmetrically distributed at an intersection of three intersecting waveguides at an angle of 120° Surrounding, and each magneto-optical material column is located on a central axis of the waveguide in which it is located; three identical third dielectric material columns are respectively disposed at a second vicinity of the second dielectric material column; The third dielectric material column is a compensation column; the three compensation columns are rotationally symmetrically distributed around the intersection center of the three crossed waveguides at an angle of 120°, and each compensation column is located on the central axis of the photonic crystal waveguide on which it is located. The electromagnetic wave signal is input from any one of the waveguide ports, and will be output from the next adjacent waveguide port, and the other port is in an isolated state to form a unidirectional circular transmission.
A high-rate and high-isolation three-port optical circulator incorporating a compensation column according to claim 1, wherein said low refractive index background medium is air, vacuum, silicon dioxide, magnesium fluoride, or A dielectric material having a refractive index of less than 1.5.
The high-rate and high-isolation three-port optical circulator introduced with a compensation column according to claim 1, wherein the first dielectric material column is a silicon material, gallium arsenide, titanium dioxide, gallium nitride, Or a dielectric material having a refractive index greater than 2.
The high-rate and high-isolation three-port optical circulator introduced with a compensation column according to claim 1, wherein the first dielectric material column has a circular, square, or regular polygonal cross section. The cross section of the first dielectric material column is preferably circular.
A three-port optical circulator with high transmission rate and high isolation introduced into a compensation column according to claim 1, wherein said photonic crystal waveguide is angularly oriented at an angle of 60° from a central portion of the photonic crystal, respectively. The horizontal direction is 180° and the horizontal direction is 300°, and a plurality of first dielectric material columns are removed, and the first dielectric material column located outside between 60° and 180° is shifted outward along the 120° axis. b. The first dielectric material column outside the 180° and 300° outer portions is translated outward by a distance b along the 240° axis, and the first dielectric material column outside the 300° and 60° directions is along the 0° axis. Translating the distance b to the right constitutes the three cross-connected photonic crystal waveguides,
The high-rate and high-isolation three-port optical circulator introduced with a compensation column according to claim 1, wherein the second dielectric material column is a silicon material, gallium arsenide, titanium dioxide, gallium nitride, Or a dielectric material having a refractive index greater than 2; the cross section of the second dielectric material column is an equilateral triangle, and the line connecting the middle portion and the three top portions is at an angle of 60° with respect to the horizontal, and at an angle of 180° with the horizontal, and The horizontal direction is 300°.
A three-port optical circulator with high transmission rate and high isolation introduced into a compensation column according to claim 1, wherein the three magneto-optical material columns are respectively ferrite materials, and the cross section thereof is circular .
A high-rate and high-isolation three-port optical circulator incorporating a compensation column according to claim 1, wherein the third dielectric material column is a silicon material, gallium arsenide, titanium dioxide, gallium nitride, or a refractive index Medium material greater than 2.
The three-port optical circulator with high transmission rate and high isolation introduced into the compensation column according to claim 1, wherein the third dielectric material column has a cross section of an equilateral triangle, a circle, or a regular polygon. The cross section of the third dielectric material column is preferably an equilateral triangle, one top of the equilateral triangle corresponds to the central axis direction of the photonic crystal waveguide in which it is located, and the top corresponds to the waveguide port direction.