CN112782804A

CN112782804A - Expandable miniaturized photonic crystal wavelength division multiplexer

Info

Publication number: CN112782804A
Application number: CN202110041405.XA
Authority: CN
Inventors: 李梦凡; 陈德媛; 张岩; 徐聪
Original assignee: Nanjing University of Posts and Telecommunications
Current assignee: Nanjing University of Posts and Telecommunications
Priority date: 2021-01-13
Filing date: 2021-01-13
Publication date: 2021-05-11
Anticipated expiration: 2041-01-13
Also published as: CN112782804B

Abstract

The invention discloses an expandable miniaturized photonic crystal wavelength division multiplexer, which comprises an input main waveguide and a plurality of output waveguides, wherein a downloading cavity is arranged between each output waveguide and the input main waveguide; the download cavity comprises an inner medium column and a plurality of outer medium columns distributed on the periphery of the inner medium column. The invention uses the inner medium column and a plurality of outer medium columns distributed on the periphery of the inner medium column to form the downloading cavity, has simple structure and small size, and is convenient for integration and expansion.

Description

Expandable miniaturized photonic crystal wavelength division multiplexer

Technical Field

The invention relates to an expandable miniaturized photonic crystal wavelength division multiplexer, and belongs to the field of two-dimensional photonic crystal devices.

Background

The photonic crystal is proposed for the first time in 1987 as a structural material with good modulation capability on optical waves, and has been widely and deeply researched for more than 50 years, so that an optical fiber and a wavelength division multiplexer can be realized.

With the rapid development of network communication and the increasing market demand, optical fibers are used as optical signal transmission carriers, and researchers are gradually turning to high-capacity compact type researches, and wavelength division multiplexers matched with the optical fibers need more intensive wavelength selection. Therefore, the compact, small-sized, high-performance wavelength division multiplexer is the target of the current design. But the design difficulty is relatively increased due to the small wavelength interval.

The photonic device based on photonic crystal design has the characteristics of flexible design, miniaturization, low power consumption and the like, the selection of the photonic crystal to design the high-performance wavelength division multiplexer is also the target which is being overcome by many researchers at present, and the design concept is mainly to realize the selection and output of different wavelengths by carrying out directional coupling between various waveguides and various resonant cavities. The currently proposed photonic crystal wavelength division multiplexer is mainly based on a ring cavity structure, and the internal structure of the ring cavity is changed to achieve higher transmittance and isolation. However, the use of the ring cavity structure inevitably results in a larger device size, and the design of the ring cavity is complicated, which is disadvantageous for optical integration and expansion.

Disclosure of Invention

The invention provides an expandable miniaturized photonic crystal wavelength division multiplexer, which solves the problems disclosed in the background technology.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows:

the expandable miniaturized photonic crystal wavelength division multiplexer comprises an input main waveguide and a plurality of output waveguides, wherein a downloading cavity is arranged between each output waveguide and the input main waveguide; the download cavity comprises an inner medium column and a plurality of outer medium columns distributed on the periphery of the inner medium column.

All the outer medium columns are uniformly distributed on the same circumference, and the circle center of the circumference is positioned on the central axis of the inner medium column.

The distance between the outer dielectric column and the inner dielectric column is 0.5a, and a is the lattice constant of the photonic crystal.

Four outer medium columns are distributed on the periphery of the inner medium column, and the four outer medium columns are opposite to each other in pairs.

Eight output waveguides are provided, a download cavity is arranged between each of the eight output waveguides and the input main waveguide, the radii of medium columns in the eight download cavities are 0.9259a, 0.8889a, 0.7685a, 0.7963a, 0.7685a, 0.8704a and 0.7596a respectively, and a is the lattice constant of the photonic crystal.

The radii of the eight download cavity external medium columns are 0.8352a, 0.8267, 0.8194a, 0.8083a, 0.8148a, 0.8217a, 0.8546a and 0.837a respectively, and a is the lattice constant of the photonic crystal.

The invention achieves the following beneficial effects: 1. the invention uses the inner medium column and a plurality of outer medium columns distributed on the periphery of the inner medium column to form the downloading cavity, has simple structure and small size, and is convenient for integration and expansion; 2. the invention can obtain different download wavelengths only by changing the radiuses of the inner medium column and the outer medium column, and can realize the wavelength division multiplexing of multiple wavelengths only by expanding the download cavity and the output waveguide.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a schematic diagram of a single output waveguide;

FIG. 3 is a graph showing the effect of varying the radius of the inner dielectric cylinder on transmission with only one loading cavity and one output waveguide;

FIG. 4 is a graph of the effect of varying the radius of the outer dielectric cylinder on transmission with only one loading cavity and one output waveguide;

FIG. 5 is a wavelength transmission spectrum of eight output waveguides;

fig. 6 is an electric field distribution diagram of the output waveguide Ch 1;

FIG. 7 is an electric field distribution diagram of the output waveguide Ch 2;

fig. 8 is an electric field distribution diagram of the output waveguide Ch 3;

fig. 9 is an electric field distribution diagram of the output waveguide Ch 4;

fig. 10 is an electric field distribution diagram of the output waveguide Ch 5;

fig. 11 is an electric field distribution diagram of the output waveguide Ch 6;

fig. 12 is an electric field distribution diagram of the output waveguide Ch 7;

fig. 13 is an electric field distribution diagram of the output waveguide Ch 8;

FIG. 14 is a graph of the crosstalk between the eight output wavelengths.

Detailed Description

The invention is further described below with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.

The expandable miniaturized photonic crystal wavelength division multiplexer comprises an input main waveguide and a plurality of output waveguides, wherein a downloading cavity is arranged between each output waveguide and the input main waveguide; the download cavity comprises an inner medium column 1 and a plurality of outer medium columns 2 distributed on the periphery of the inner medium column 1, all the outer medium columns 2 are uniformly distributed on the same circumference, and the circle center of the circumference is located on the central axis of the inner medium column 1.

The wavelength division multiplexer forms the download cavity by the inner medium column 1 and the plurality of outer medium columns 2 distributed on the periphery of the inner medium column 1, and has the advantages of simple structure, small size and convenience for integration and expansion; different download wavelengths can be obtained only by changing the radiuses of the inner medium column 1 and the outer medium column 2, and the wavelength division multiplexing of multiple wavelengths can be realized only by expanding the download cavity and the output waveguide.

As shown in fig. 1, an example of the wavelength division multiplexer, specifically, an eight-channel wavelength division multiplexer based on photonic crystals, includes an input main waveguide and eight output waveguides, where a downloading cavity is disposed between each of the eight output waveguides and the input main waveguide, that is, there are eight downloading cavities, where each downloading cavity includes an inner medium column 1 and four outer medium columns 2 distributed around the inner medium column 1, and the four outer medium columns 2 are opposite to each other.

The photonic crystal is a two-dimensional photonic crystal and is formed by triangular lattice dielectric column triangular arrays arranged in air, the refractive index of background air is 1, the dielectric columns of the triangular arrays are cylinders, the material is silicon, the refractive index is 3.4, the radius of the dielectric columns of the triangular arrays is 0.18a, and a is the lattice constant of the photonic crystal. The photonic crystal waveguide has a waveguide width of 2a and a length of n x a, wherein n is an integer not less than 4.

The outer medium column 2 and the inner medium column 1 are also cylinders made of silicon, and the distance between the outer medium column 2 and the inner medium column 1 is 0.5 a. The radii of the eight download cavity media columns 1 are 0.9259a, 0.8889a, 0.7685a, 0.7963a, 0.7685a, 0.8704a and 0.7596a respectively; the radii of the eight download cavity external medium columns 2 are 0.8352a, 0.8267, 0.8194a, 0.8083a, 0.8148a, 0.8217a, 0.8546a and 0.837a respectively, and a is the lattice constant of the photonic crystal.

According to the coupled mode theory, the radius of the inner dielectric column 1 and the radius of the outer dielectric column 2 of the download cavity have influence on the selected wavelength, and the transmittance, the quality, the isolation and the insertion loss of the selected wavelength of the device can be optimized by optimizing the radius of the inner dielectric column 1 and the radius of the outer dielectric column 2 of the download cavity.

The following results were obtained by software simulation:

as shown in fig. 2, when the device has only one loading cavity and one output waveguide, only one wavelength can be selected and the device has a filtering function.

As shown in FIG. 3, the radius of the outer dielectric cylinder 2 is kept constant, only the radius of the inner dielectric cylinder 1 is changed, and the wavelength selected by the lower cavity to the output waveguide is hardly changed, but the transmissivity is obviously different.

As shown in fig. 4, the wavelength selected by the down loading cavity to the output waveguide changes only by changing the radius of the outer dielectric cylinder 2 while keeping the radius of the inner dielectric cylinder 1 constant, and the wavelength moves to the right as the radius of the outer dielectric cylinder 2 becomes larger. The transmission can be adjusted by changing the radius of the inner dielectric cylinder 1, and different download wavelengths can be selected by changing the radius of the outer dielectric cylinder 2.

As shown in fig. 5, light enters from the input main waveguide, and since the mode of each download cavity is different, the wavelength selected by each download cavity is different, and eight output waveguides output light with different wavelengths respectively, as shown in fig. 6 to 14.

The expandable miniaturized photonic crystal wavelength division multiplexer utilizes the inner medium column 1 and the outer medium column 2 to form a high-quality downloading cavity, obtains eight high-transmission and high-isolation wavelengths by optimizing the radius of the inner medium column 1 and the radius of the outer medium column 2, reduces the interval between the wavelengths, and realizes quasi-densification. The wavelength average transmittance of the wavelength division multiplexer is 92.5%, the minimum isolation is 12dB, the quality factor is more than 3000, and the low insertion loss is realized. In addition, the miniaturization of the high-quality cavity enables the miniaturization of the device, and the size of the device is only 217.8um²And can increase smaller area when expanding cavity and output channel, very favorable to the light integration, is suitable for the optical fiber communication system field.

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

1. Extensible miniaturized photonic crystal wavelength division multiplexer, its characterized in that: the optical fiber coupler comprises an input main waveguide and a plurality of output waveguides, wherein a downloading cavity is arranged between each output waveguide and the input main waveguide; the download cavity comprises an inner medium column and a plurality of outer medium columns distributed on the periphery of the inner medium column.

2. The scalable miniaturized photonic crystal wavelength division multiplexer according to claim 1, wherein: all the outer medium columns are uniformly distributed on the same circumference, and the circle center of the circumference is positioned on the central axis of the inner medium column.

3. The scalable miniaturized photonic crystal wavelength division multiplexer according to claim 2, wherein: the distance between the outer dielectric column and the inner dielectric column is 0.5a, and a is the lattice constant of the photonic crystal.

4. The scalable miniaturized photonic crystal wavelength division multiplexer according to any one of claims 1 to 3, wherein: four outer medium columns are distributed on the periphery of the inner medium column, and the four outer medium columns are opposite to each other in pairs.

5. The scalable miniaturized photonic crystal wavelength division multiplexer according to claim 1, wherein: eight output waveguides are provided, a download cavity is arranged between each of the eight output waveguides and the input main waveguide, the radii of medium columns in the eight download cavities are 0.9259a, 0.8889a, 0.7685a, 0.7963a, 0.7685a, 0.8704a and 0.7596a respectively, and a is the lattice constant of the photonic crystal.

6. The scalable miniaturized photonic crystal wavelength division multiplexer according to claim 5, wherein: the radii of the eight download cavity external medium columns are 0.8352a, 0.8267, 0.8194a, 0.8083a, 0.8148a, 0.8217a, 0.8546a and 0.837a respectively, and a is the lattice constant of the photonic crystal.