CN111856656B - Four-channel drop filter with photonic crystal structure - Google Patents
Four-channel drop filter with photonic crystal structure Download PDFInfo
- Publication number
- CN111856656B CN111856656B CN202010720667.4A CN202010720667A CN111856656B CN 111856656 B CN111856656 B CN 111856656B CN 202010720667 A CN202010720667 A CN 202010720667A CN 111856656 B CN111856656 B CN 111856656B
- Authority
- CN
- China
- Prior art keywords
- dielectric
- resonant cavity
- columns
- column
- medium
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
- G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
- G02B6/293—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
- G02B6/29331—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means operating by evanescent wave coupling
- G02B6/29335—Evanescent coupling to a resonator cavity, i.e. between a waveguide mode and a resonant mode of the cavity
- G02B6/29338—Loop resonators
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
- G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
- G02B6/293—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
- G02B6/29379—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means characterised by the function or use of the complete device
- G02B6/2938—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means characterised by the function or use of the complete device for multiplexing or demultiplexing, i.e. combining or separating wavelengths, e.g. 1xN, NxM
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Optical Integrated Circuits (AREA)
Abstract
The invention discloses a four-channel drop filter with a photonic crystal structure, which is a two-dimensional photonic crystal with a tetragonal lattice dielectric column structure and consists of an input waveguide, two through output waveguides and two resonant cavities with square double-ring structures. The dielectric column material of the whole structure is a phase change material, and the four-channel down-circuit filtering function meeting the requirements of a coarse wavelength division multiplexing optical communication system can be realized by inducing the inner ring dielectric columns of the two square double-ring structure resonant cavities, the upper coupling dielectric columns and the lower coupling dielectric columns to different phase change states from the outside. Compared with the four-channel drop filter with other photonic crystal structures, the filter has the advantages that the number of the resonant cavities is reduced by half, only two resonant cavities with square double-ring structures are needed except for input and output waveguides, the filter has the outstanding characteristics of simple structure, small size, easiness in realization and integration, high flexibility, drop output wavelength meeting the design requirement of the nominal wavelength of the optical communication system in actual application at present, and the filter has important application in future optical integrated systems.
Description
Technical Field
The invention relates to a four-channel drop filter with a photonic crystal structure, which is mainly applied to a wavelength division multiplexing communication system to realize selective drop of specific multiple wavelength signals.
Background
The emergence and development of Wavelength Division Multiplexing (WDM) technology have greatly improved the transmission capacity and transmission efficiency of optical communication networks, making people enter the era of high-capacity, low-loss, high-speed communications. The optical channel drop filter is an important component of a WDM system, can realize multiplexing and demultiplexing functions of optical signals, and has important application in the WDM system. With the further development of the WDM technology, the corresponding requirements on various optical devices are higher and higher, and designing and realizing a multi-channel drop filter with a small size, a simple structure, and high drop efficiency and flexibility is more and more significant, and has significant effects on the aspects of improving the system integration level, improving the system resource utilization rate, reducing the device redundancy, and the like.
Prior art [1]Referring to Optik, alipour-Banaiei H, mehdizadehF, serajmohammadi S.2013,124:5964-5967, the four-channel optical drop filter is realized by introducing four X-shaped resonant cavities with different parameters into a triangular lattice two-dimensional photonic crystal. The wavelength of the down path is 1563.5nm, 1566.2nm, 1569.7nm and 1572.6nm respectively, the average down path efficiency is 53 percent, and the overall structure size is about 800 mu m 2 . It can be seen that the channel drop filter has low drop efficiency and dropsThe wavelength also does not accord with the design requirement of the nominal wavelength of the CWDM system or the DWDM system in practical application, and because the structure needs to be realized by four resonant cavities with different parameters, the structure is complex and the size is larger.
Prior art [2]Referring to optical precision engineering, shenmacrojun, liujie, litting, liselan 2015, 23-699, four hexagonal resonant cavities with six central medium columns inside are introduced into a two-dimensional photonic crystal of a triangular lattice, and the radiuses of the six central medium columns inside the four resonant cavities are adjusted, so that a channel drop output function of four different wavelengths is realized, the four resonant wavelengths are 1581.9nm, 1592.3nm, 1601.3nm and 1607.3nm respectively, the average drop efficiency is more than 90%, and the overall structure size is about 655 μm 2 . Although the structure realizes the high-efficiency downlink output function, the four-channel downlink output still needs four resonant cavities with different parameters, and the structure is complex. In addition, the four downlink wavelengths do not meet the specific requirements of the WDM system commonly adopted at present, such as Coarse Wavelength Division Multiplexing (CWDM) or Dense Wavelength Division Multiplexing (DWDM), on the wavelength of the transmission signal; the four resonant cavities for realizing the four-channel downlink output need to be based on the processing parameters, namely, the radius of six central medium columns in the resonant cavities is changed, so that the actual preparation is not facilitated.
Prior art [3]See applied optics, S.Yaw-DongWu, tien-TsingShih, jian-JangLee.2009,48: F24-F30, four square ring resonators with nine dielectric cylinders in the center are introduced into a square two-dimensional photonic crystal, the radius of the dielectric cylinders in the four square resonators is selected appropriately, the down-circuit output of signals with four different wavelengths of 1510nm, 1530nm, 1550nm and 1570nm is realized, the average transmittance is more than 92%, and the overall structure size is about 384 mu m 2 . The structure also needs four resonant cavities for realizing the downlink output of four channels, and the downlink output for realizing the four channels needs to be based on processing parameters, namely the radius of nine medium columns in the center is changed, so that the structure is not beneficial to actual preparation.
Prior art [4]See Photonic Network Communications, hamed Alipay-Banaii, somayye Serajmohammadi and Farhad Mehdizadeh.2015,29,four square ring-shaped resonant cavities with central dielectric columns arranged in an octagonal array are introduced into a square lattice two-dimensional photonic crystal, and the appropriate lattice constant of the central dielectric columns of the four resonant cavities is selected, so that the downlink output of signals with four wavelengths of 1569.5nm,1572.5nm,1575.5nm and 1577.5nm is realized, the downlink efficiency is over 95 percent, and the overall structure size is about 800 mu m 2 . Although the structure also realizes the high-efficiency downlink output function, four resonant cavities are needed for realizing the downlink output of four channels, and the whole size of the device is larger. In addition, the structure for realizing the four-channel down-link output needs to be based on the change of processing parameters, namely the lattice constant of a dielectric column in the resonant cavity, so that the structure is not beneficial to practical preparation. On the other hand, the four drop wavelengths do not meet the specific requirements of the WDM system commonly used at present, such as Coarse Wavelength Division Multiplexing (CWDM) or Dense Wavelength Division Multiplexing (DWDM), on the wavelength of the transmission signal.
Disclosure of Invention
In order to solve the problems in the prior art, the present invention aims to overcome the disadvantages in the prior art, and provide a four-channel drop filter with a photonic crystal structure, which has a simple structure, a small size, easy preparation, and excellent optical performance, and the wavelengths of multiple signals to be dropped meet the design requirements of the nominal wavelength of the CWDM system in practical application, and has stronger practicability.
In order to achieve the purpose of the invention, the invention adopts the following inventive concept:
the common characteristic that only one wavelength signal can be dropped by one resonant cavity of the existing multichannel drop filter is improved, a novel annular resonant cavity is designed, two wavelength signals can be dropped forwards and backwards at a drop waveguide at the same time, and other wavelengths are transmitted in high transmission mode continuously in an input waveguide. The novel ring resonator is the key to the design of the whole four-channel down-filter. After the two wavelengths are subjected to resonance and downlink by the first ring-shaped resonant cavity, the other two wavelengths which are transmitted in the input waveguide in a high transmission mode are subjected to resonance when passing through another ring-shaped resonant cavity with the same structure and the same processing parameters but different refractive indexes of the medium columns at certain positions, and finally, the two wavelengths are subjected to forward and backward downlink output simultaneously by another downlink waveguide, so that the downlink filtering function of the four-wavelength channel meeting the required wavelength is realized finally. The dielectric column material of the whole structure is selected as a phase change material, and the change of the refractive index of the dielectric column is flexibly realized by inducing the relevant dielectric columns in the two resonant cavities to different phase changes from the outside. The channel drop filter structurally only adopts two ring-shaped resonant cavities with the same physical structure, the refractive indexes of the medium columns at certain positions are different, phase-change materials are preferably selected as medium column materials, the phase-change materials are induced to be different from each other through the outside, the required refractive index is flexibly realized, and the drop output of four-wavelength signals can be realized, so that the outstanding problems that the structure is complex, the size is large and the actual preparation is not facilitated due to the fact that four resonant cavities with different processing parameters are required for the drop of four-wavelength signals commonly existing in the prior art are solved. By selecting proper lattice constants, refractive indexes, radiuses and the like of the background medium columns, the four wavelengths of the lower path can meet the specific requirements of CWDM system application, and meanwhile, the filter has excellent lower path filtering characteristics.
According to the inventive concept, the invention adopts the following technical scheme:
a four-channel drop filter with a photonic crystal structure adopts a two-dimensional photonic crystal of a tetragonal lattice dielectric column type as a basic structure, and is composed of an input waveguide, two through output waveguides and two resonant cavities with square double-ring structures, wherein the two through output waveguides comprise an upper output waveguide and a lower output waveguide, the two resonant cavities with square double-ring structures comprise a first resonant cavity and a second resonant cavity, and the first resonant cavity and the second resonant cavity are arranged between the upper output waveguide and the lower output waveguide.
Preferably, the dielectric column material of the overall structure of the four-channel drop filter of the photonic crystal structure is a phase change material, the inner ring dielectric columns of the two square double-ring structure resonant cavities, the upper coupling dielectric columns and the lower coupling dielectric columns are induced to different phase changes by the outside, and the lattice constant, the refractive index and the radius of the background dielectric column, the radius of the dielectric column at other special positions, and the like are selected at the same time to form the four-channel drop filter structure of the Coarse Wavelength Division Multiplexing (CWDM) optical communication system.
Preferably, the input waveguide of the four-channel drop filter of the photonic crystal structure is formed by successively removing a plurality of dielectric pillars in the horizontal array direction at the input port, the ends of which do not form a via; the upper output waveguide and the lower output waveguide are respectively positioned at the upper side and the lower side of the input waveguide, and the dielectric columns of the whole array are continuously removed along the horizontal array direction, so that the straight-through output waveguide with the passage in both directions is formed.
Preferably, the first resonant cavity of the quad-dual-ring structure of the four-channel drop filter of the photonic crystal structure is located between the input waveguide and the upper output waveguide; the second resonant cavity of the square double-ring structure is positioned between the input waveguide and the lower output waveguide; the positions of the first resonant cavity and the second resonant cavity of the square double-ring structure in the horizontal direction are different.
Preferably, the first resonant cavity and the second resonant cavity of the square double-ring structure of the four-channel drop filter of the photonic crystal structure are both composed of an inner dielectric column arrangement structure and an outer dielectric column arrangement structure which are arranged in a square shape; the medium column arrangement structure with the square shape is characterized in that oval medium columns are respectively arranged at the inner positions of four corners and are used as scattering medium columns; in the arrangement structure of the medium columns with square shapes, except the medium columns positioned at the four outermost corners, the medium columns in other horizontal directions are also oval and used as an upper coupling medium column and a lower coupling medium column; the inner and outer two medium column arrangement structures which are arranged in a square shape are not adjacent to each other, at least one row of medium columns are arranged at intervals to form an annular cavity which is used as an outer ring of the resonant cavity; the dielectric column arrangement structure with the square inner shape has no dielectric column inside, and forms another annular cavity as an inner ring of the resonant cavity, thereby forming the resonant cavity with a double-ring structure; the long axis and the short axis of the scattering medium column are not coincident with the horizontal direction and the vertical direction, and form a set included angle; the long and short axes of the upper and lower coupling medium columns are respectively coincided with the horizontal and vertical directions; the spacing between the medium columns of the medium column arrangement structure is not more than that of the medium column arrangement structure of the outer square shape.
Preferably, the refractive indexes of the inner ring dielectric cylinder and the outer ring dielectric cylinder of the first resonant cavity and the second resonant cavity of the four-channel drop filter with the photonic crystal structure are different; the refractive indexes of the upper coupling medium column and the lower coupling medium column in the second resonant cavity are different; the refractive index of the inner ring dielectric cylinder of the first resonant cavity is different from that of the inner ring dielectric cylinder of the second resonant cavity; the refractive indexes of the upper and lower coupling medium columns of the first resonant cavity are different from the refractive indexes of the upper and lower coupling medium columns of the second resonant cavity; during preparation, the dielectric column materials at all positions are selected as phase change materials, and based on the phase change characteristics of the dielectric column materials, the required refractive index of the dielectric column is realized by inducing the relevant dielectric columns of the two resonant cavities to different phase change states from the outside.
Preferably, by selecting a suitable lattice constant, a refractive index and a radius of the background dielectric column, a refractive index and a radius of the relevant dielectric column of the first resonant cavity and the second resonant cavity, a horizontal position of the first resonant cavity and the second resonant cavity, and the like, the downlink output of four wavelengths meeting the downlink wavelength size and wavelength interval requirements of the CWDM optical communication system is simultaneously realized, and simultaneously, the downlink efficiency is high.
Compared with the prior art, the invention has the following obvious and prominent substantive characteristics and remarkable advantages:
1. the four-channel drop filter of the filter is realized only based on two resonant cavities with square double-ring structures with the same processing parameters, so compared with the prior art that four resonant cavities are needed for realizing the drop output of four channels, the four-channel drop filter has the outstanding characteristics of simple structure, small size and easy realization; in addition, compared with the defect that the wavelength of the four downlink signals in the prior art cannot meet the application requirement of an actual system, the wavelength and the wavelength interval of the four downlink signals realized by the structure of the invention meet the design requirement of the CWDM system in the current actual application, and the invention has higher practicability; compared with the lower route taking efficiency in the prior art, the structure can realize higher route taking efficiency and has more excellent performance;
2. the resonant cavities of the two square double-ring structures of the filter have the same structural parameters required by the processing except for the refractive indexes of the medium columns at partial positions; during preparation, all dielectric column materials are selected as phase-change materials, and based on the phase-change characteristics of the dielectric column materials, the required refractive index of the dielectric column can be flexibly realized by simply inducing the dielectric columns at the relevant positions of the two resonant cavities to the phase-change state corresponding to the required refractive index from the outside, so that compared with the prior art that the structural parameters of each resonant cavity are different and a plurality of dielectric columns with different refractive indexes and radiuses need to be additionally prepared, the phase-change material is simple in structural preparation, easy to realize and has higher flexibility and practicability;
3. compared with the four-channel drop filter with other structures, the four-channel drop filter has the advantages that the number of the required resonant cavities is reduced by half, the structure is simple, the size is small, the implementation is easy, the drop output wavelength size and the gap meet the design requirements of the CWDM system in the current practical application, and the four-channel drop filter has important application in the future all-optical integrated optical communication network.
Drawings
Fig. 1 is a schematic diagram of a four-channel drop filter according to the present invention. Wherein 1 is an input waveguide, 2 and 3 are an upper output waveguide and a lower output waveguide respectively, and 4 and 5 are resonant cavities with square double-ring structures. A is the input port, and B, C, D and E ports are the output ports of the down path.
Fig. 2 is a schematic structural diagram of the square dual-ring resonator shown in fig. 1. The medium columns which are positioned inside and arranged in a square shape are called inner ring medium columns; the medium columns are arranged in a square shape and positioned at the outer part, and the four medium columns are positioned at the four corners and have oval shapes, and are called outer ring medium columns.
FIG. 3 is a key dielectric column in the outer ring dielectric column of the quad-double ring resonator shown in FIG. 2. The medium columns shown by the upper and lower rounded rectangle frames are called upper and lower coupling medium columns; the dielectric cylinder with four corners shown as triangular boxes is called a scattering dielectric cylinder.
Table 1 shows the structural parameters of the key dielectric pillars of the first cavity 4 and the second cavity 5 according to the preferred embodiment of the present invention.
Fig. 4 is a transmission spectrum of four output ports of the preferred embodiment of the present invention.
FIG. 5 is a graph showing the distribution of the optical field at different drop wavelengths in a preferred embodiment of the present invention. Wherein the wavelength of the down path is 1550nm, 1570nm,1590nm, 1610nm.
During specific design, a proper lattice constant, a background dielectric column refractive index and a radius are selected, so that the wavelengths of four signals which are to be dropped and meet the specific application of the CWDM are located in a photonic band gap of the photonic crystal. The four-wavelength signals to be dropped are input from the input port of the input waveguide 1, the refractive index and the radius of the inner ring dielectric column of the second resonant cavity 5, the refractive index of the upper coupling dielectric column and the refractive index of the lower coupling dielectric column as well as the length of the long half shaft and the length of the short half shaft, the length of the long half shaft and the short half shaft of the scattering dielectric column and the like are selected, two wavelength signals in the four-wavelength signals input through the input waveguide 1 can be coupled with the second resonant cavity 5, and are respectively dropped forwards and backwards after passing through the lower horizontal straight-through output waveguide 3 and output from the output ports D and E, and the rest two wavelengths are continuously transmitted in the input waveguide in a high transmission mode. And selecting the refractive index and the radius of the inner ring dielectric column of the first resonant cavity 4 to couple the other two wavelength signals with the first resonant cavity 4, and finally respectively outputting the other two wavelength signals from the output ports B and C after passing through the upper horizontal through output waveguide 2 in a forward and backward downward way, thereby finally realizing the downward filtering of the four wavelength signals. The phase-change material is selected as the dielectric column material, and the refractive index of the dielectric column at the relevant position can be flexibly changed based on the phase-change characteristics of the material, so that the practical application is facilitated.
Detailed Description
The above-described embodiments are further illustrated below with reference to specific examples, in which preferred embodiments of the invention are detailed below:
the first embodiment is as follows:
in this embodiment, referring to fig. 1, a four-channel drop filter with a photonic crystal structure, whose basic structure adopts a two-dimensional photonic crystal of a tetragonal lattice dielectric column type, is composed of an input waveguide 1, two through output waveguides and two resonant cavities with a square double-ring structure, where the two through output waveguides include an upper output waveguide 2 and a lower output waveguide 3, the two resonant cavities with the square double-ring structure include a first resonant cavity 4 and a second resonant cavity 5, and the first resonant cavity 4 and the second resonant cavity 5 are disposed between the upper output waveguide 2 and the lower output waveguide 3.
The second embodiment:
the present embodiment is substantially the same as the first embodiment, and the special points are that:
in this embodiment, referring to fig. 1 to 3, the four-channel drop filter with a photonic crystal structure is characterized in that: the dielectric column material of the whole structure is a phase change material, the inner ring dielectric columns of the two square double-ring structure resonant cavities, the upper coupling dielectric columns and the lower coupling dielectric columns are induced to different phase metamorphoses by the outside, and the lattice constant, the refractive index and the radius of the background dielectric column and the radius of the dielectric column at other special positions are simultaneously selected to form a four-channel lower filter structure of a Coarse Wavelength Division Multiplexing (CWDM) optical communication system.
In the present embodiment, the input waveguide 1 is constituted by successively removing a plurality of dielectric pillars in the horizontal array direction at the input port, the ends of which do not constitute a passage; the upper output waveguide 2 and the lower output waveguide 3 are respectively positioned at the upper side and the lower side of the input waveguide 1, and a through output waveguide with a passage in both directions is formed by continuously removing the dielectric columns of the whole array along the horizontal array direction. The first resonant cavity 4 of the square double-ring structure is positioned between the input waveguide 1 and the upper output waveguide 2; the second resonant cavity 5 of the square double-ring structure is positioned between the input waveguide 1 and the lower output waveguide 3; the first resonant cavity 4 and the second resonant cavity 5 of the square double-ring structure are different in position in the horizontal direction.
Example three:
this embodiment is substantially the same as the previous embodiment, and is characterized in that:
in the present embodiment, referring to fig. 1-3, the first resonant cavity 4 and the second resonant cavity 5 of the square dual-ring structure are both composed of an inner dielectric pillar arrangement structure and an outer dielectric pillar arrangement structure which are arranged in a square shape; the medium column arrangement structure with the square outer shape is provided with an oval medium column as a scattering medium column at the inner positions of four corners; in the arrangement structure of the medium columns with square shapes, except the medium columns positioned at the four outermost corners, the shapes of other medium columns in the horizontal direction are also ellipses and are used as an upper coupling medium column and a lower coupling medium column; the inner and outer dielectric column arrangement structures which are arranged in a square shape are not adjacent to each other, and at least one row of dielectric columns are arranged at intervals to form an annular cavity which is used as the outer ring of the resonant cavity; the dielectric column arrangement structure with the square inner shape has no dielectric column inside, and forms another annular cavity as an inner ring of the resonant cavity, thereby forming the resonant cavity with a double-ring structure; the long axis and the short axis of the scattering medium column are not coincident with the horizontal direction and the vertical direction, and form a set included angle; the long and short axes of the upper and lower coupling medium columns are respectively coincided with the horizontal and vertical directions; the medium column interval of the medium column arrangement structure is not larger than that of the medium column arrangement structure with the square shape at the outer side.
In this embodiment, the refractive indexes of the inner ring dielectric cylinder and the outer ring dielectric cylinder of the first resonant cavity 4 and the second resonant cavity 5 are different; the refractive indexes of the upper coupling medium column and the lower coupling medium column in the second resonant cavity 5 are different; the refractive index of the inner ring dielectric cylinder of the first resonant cavity 4 is different from that of the inner ring dielectric cylinder of the second resonant cavity 5; the refractive indexes of the upper and lower coupling medium columns of the first resonant cavity 4 are different from the refractive indexes of the upper and lower coupling medium columns of the second resonant cavity 5; during preparation, the dielectric column materials at all positions are selected as phase change materials, and based on the phase change characteristics of the dielectric column materials, the required refractive index of the dielectric column is realized by inducing the relevant dielectric columns of the two resonant cavities to different phase change states from the outside.
In this embodiment, by selecting a suitable lattice constant, a refractive index and a radius of the background dielectric column, a refractive index and a radius of the dielectric column related to the first resonant cavity 4 and the second resonant cavity 5, and positions of the first resonant cavity 4 and the second resonant cavity 5 in the horizontal direction, etc., the drop output of four wavelengths meeting the requirements of the drop wavelength size and the wavelength interval of the CWDM optical communication system is simultaneously realized, and the drop efficiency is high.
Example four:
this embodiment is substantially the same as the previous embodiment, and is characterized in that:
the implementation is applied to a CWDM optical communication system, and the lower wavelengths with the nominal wavelength interval of 20nm are respectively as follows: 1550nm, 1570nm,1590nm and 1610nm.
The whole optical system structure is shown in fig. 1. It is a tetragonal lattice mediumThe whole structure of the two-dimensional photonic crystal with the column structure is a 27 multiplied by 31 dielectric column array, an A port is an input port, and B, C, D and E ports are downlink output ports. The background material is air, and the dielectric column material is phase-change material Ge 2 Sb 2 Se 4 Te 1 The refractive index n =3.46, the dielectric cylinder radius R =0.08 μm, and the lattice constant a =0.58 μm. The input waveguide is formed by continuously removing 18 dielectric columns along the horizontal direction at the input end A, and the two output waveguides are formed by continuously removing a whole row of dielectric columns along the horizontal direction at the output end respectively. The first resonant cavity 4 and the second resonant cavity 5 are of a symmetrical structure, the middle shaft position of the first resonant cavity 4 is separated from the first row of dielectric columns of the integral structure by 15 dielectric columns in the vertical direction, the middle shaft position of the second resonant cavity 5 is separated from the first row of dielectric columns of the integral structure by 5 dielectric columns in the vertical direction, and namely the first resonant cavity 4 is compared with the second resonant cavity 5 and is shifted to the right by 10 dielectric columns in the horizontal direction. The first resonant cavity 4 and the second resonant cavity 5 have a half of lattice constant as the inner ring dielectric column spacing and a lattice constant equal to the outer ring dielectric column spacing. The structural parameters of the key dielectric columns of the first resonant cavity 4 and the second resonant cavity 5 are shown in Table 1, the other dielectric column parameters are the same as the background dielectric column parameters, and the size of the whole structure is 296 μm 2 。
TABLE 1 structural parameters of the key dielectric pillars of the first cavity 4 and the second cavity 5 of the fourth embodiment of the present invention
By inputting a gaussian pulse signal of TE polarization at the input port a and observing at the ports B, C, D, and E, the transmission spectrum obtained is as shown in fig. 4. At the input waveguide port a, continuous wavelength signals of single wavelengths 1550nm, 1570nm,1590nm and 1610nm are input, respectively, and the obtained optical field distribution is as shown in fig. 5. As can be seen from fig. 5, the filter simultaneously realizes the output of the 1550nm wavelength, the 1570nm wavelength, the 1590nm wavelength and the 1610nm wavelength from the output ports C, B, E and D, respectively. It can be calculated from fig. 4 that the transmission at ports C, B, E and D is 90.81%, 80.31%, 84.72% and 96.84% for the drop wavelengths 1550nm, 1570nm,1590nm and 1610nm, respectively.
In summary, the four-channel drop filter realizes the four-channel drop filtering function of 1550nm, 1570nm,1590nm and 1610nm wavelengths meeting the standard wavelength interval of 20nm of a CWDM optical communication system only based on the two resonant cavities with the square double-ring structure, and has the advantages of simple structure, small size, easy integration and ideal drop filtering characteristics. In addition, the resonant cavities of the two square double-ring structures have the same structural parameters required by processing except that the refractive indexes of the medium columns at partial positions are different. During preparation, the required refractive index of the dielectric column can be realized by inducing the inner ring dielectric columns of the two resonant cavities and the upper and lower coupling dielectric columns to different phase transformation states from the outside under the condition that the materials of all the dielectric columns are the same. Therefore, compared with the prior art, the structure of the invention is easier to prepare and realize, and has higher flexibility and practicability.
In this embodiment, the four wavelengths of the drop filtering are 1550nm, 1570nm,1590nm and 1610nm, and based on the design structure and design idea of the present invention, a four-channel drop filter in which the size and the interval of other drop output wavelengths meet the design requirements of the CWDM system in practical application at present can be realized. The wavelength of the down path is 1550nm, 1570nm,1590nm and 1610nm, respectively, and the filter has excellent down path filtering characteristics and an overall structure size of 296 μm 2 。
It can be known from the above embodiments that the four-channel drop filter of the photonic crystal structure of the present invention is a two-dimensional photonic crystal with a tetragonal lattice dielectric pillar structure, and is composed of an input waveguide, two through output waveguides, and two specially designed resonant cavities with a tetragonal double-ring structure. The dielectric column material of the whole structure is a phase change material, the inner ring dielectric columns of the two square double-ring structure resonant cavities, the upper coupling dielectric columns and the lower coupling dielectric columns are induced to different phase changes by the outside, and the proper lattice constant, the refractive index and the radius of the background dielectric column and the radius of the dielectric column at other special positions are selected at the same time, so that the four-channel down-path filtering function meeting the requirements of a Coarse Wavelength Division Multiplexing (CWDM) optical communication system can be realized. Compared with the four-channel drop filter with other photonic crystal structures, the four-channel drop filter has the advantages that the number of resonant cavities is reduced by half, only two resonant cavities with square double-ring structures are needed except for input and output waveguides, the four-channel drop filter has the outstanding characteristics of simple structure, small size and easiness in realization and integration, the flexibility is high, the drop output wavelength meets the design requirement of the nominal wavelength of the CWDM optical communication system in actual application at present, and the four-channel drop filter has important application in future optical integrated systems.
The embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made according to the purpose of the invention, and all changes, modifications, substitutions, combinations or simplifications made according to the spirit and principle of the technical solution of the present invention shall be made in the form of equivalent substitution, so long as the invention is in accordance with the purpose of the invention, and the invention shall fall within the protection scope of the present invention as long as the technical principle and the inventive concept of the present invention are not departed from the present invention.
Claims (7)
1. A four-channel drop filter of a photonic crystal structure is characterized in that: the photonic crystal adopts a two-dimensional photonic crystal of a tetragonal lattice dielectric column type as a basic structure, and is composed of an input waveguide (1), two through output waveguides and two resonant cavities of square double-ring structures, wherein the two through output waveguides comprise an upper output waveguide (2) and a lower output waveguide (3), the two resonant cavities of square double-ring structures comprise a first resonant cavity (4) and a second resonant cavity (5), and the first resonant cavity (4) and the second resonant cavity (5) are arranged between the upper output waveguide (2) and the lower output waveguide (3).
2. The photonic crystal structured four-channel drop filter of claim 1, wherein: the dielectric column material of the whole structure is a phase change material, the inner ring dielectric columns of the two square double-ring structure resonant cavities and the upper and lower coupling dielectric columns are induced to different phase change states by the outside, and the lattice constant, the refractive index and the radius of the background dielectric column and the radii of the inner ring dielectric columns, the upper and lower coupling dielectric columns and the scattering dielectric column of the two square double-ring structure resonant cavities are simultaneously selected to form a four-channel down-path filtering structure of the coarse wavelength division multiplexing optical communication system.
3. The four-channel drop filter of the photonic crystal structure of claim 1, wherein: the input waveguide (1) is formed by continuously removing a plurality of dielectric cylinders along the horizontal array direction at an input port, and the tail end of the input waveguide does not form a passage; the upper output waveguide (2) and the lower output waveguide (3) are respectively positioned at the upper side and the lower side of the input waveguide (1), and the dielectric columns of the whole array are continuously removed along the horizontal array direction, so that a through output waveguide with both directions being communicated is formed.
4. The four-channel drop filter of the photonic crystal structure of claim 1, wherein: the first resonant cavity (4) of the square double-ring structure is positioned between the input waveguide (1) and the upper output waveguide (2); a second resonant cavity (5) with a square double-ring structure is positioned between the input waveguide (1) and the lower output waveguide (3); the positions of the first resonant cavity (4) and the second resonant cavity (5) of the square double-ring structure in the horizontal direction are different.
5. The four-channel drop filter of the photonic crystal structure of claim 1, wherein: the first resonant cavity (4) and the second resonant cavity (5) of the square double-ring structure are both composed of an inner dielectric column arrangement structure and an outer dielectric column arrangement structure which are arranged in a square shape;
the medium column arrangement structure with the square shape is characterized in that oval medium columns are respectively arranged at the inner positions of four corners and are used as scattering medium columns;
in the arrangement structure of the medium columns with square shapes, except the medium columns positioned at the four outermost corners, the shapes of other medium columns in the horizontal direction are also ellipses and are used as an upper coupling medium column and a lower coupling medium column;
the inner and outer dielectric column arrangement structures which are arranged in a square shape are not adjacent to each other, and at least one row of dielectric columns are arranged at intervals to form an annular cavity which is used as the outer ring of the resonant cavity;
the dielectric column arrangement structure with the square inner shape has no dielectric column inside, and forms another annular cavity as an inner ring of the resonant cavity, thereby forming the resonant cavity with a double-ring structure;
the long axis and the short axis of the scattering medium column are not coincident with the horizontal direction and the vertical direction, and form a set included angle; the long and short shafts of the upper and lower coupling medium columns are respectively superposed with the horizontal and vertical directions; the spacing between the medium columns of the medium column arrangement structure is not more than that of the medium column arrangement structure of the outer square shape.
6. The photonic crystal structured four-channel drop filter of claim 1, wherein: the refractive indexes of the inner ring dielectric cylinder and the outer ring dielectric cylinder of the first resonant cavity (4) and the second resonant cavity (5) are different; the refractive indexes of the upper coupling medium column and the lower coupling medium column in the second resonant cavity (5) are different; the refractive index of the inner ring dielectric cylinder of the first resonant cavity (4) is different from that of the inner ring dielectric cylinder of the second resonant cavity (5); the refractive indexes of the upper and lower coupling medium columns of the first resonant cavity (4) are different from the refractive indexes of the upper and lower coupling medium columns of the second resonant cavity (5); during preparation, the dielectric column materials at all positions are selected as phase change materials, and based on the phase change characteristics of the dielectric column materials, the required refractive index of the dielectric column is realized by inducing the relevant dielectric columns of the two resonant cavities to different phase change states from the outside.
7. The four-channel drop filter of the photonic crystal structure of any one of claims 1 to 6, wherein: by selecting the lattice constant, the refractive index and the radius of the background medium column, the refractive index and the radius of the related medium columns of the first resonant cavity (4) and the second resonant cavity (5) and the positions of the first resonant cavity (4) and the second resonant cavity (5) in the horizontal direction, the downlink output of four wavelengths meeting the downlink wavelength size and wavelength interval requirements of the CWDM optical communication system is realized at the same time, and the high downlink efficiency is realized at the same time.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010720667.4A CN111856656B (en) | 2020-07-24 | 2020-07-24 | Four-channel drop filter with photonic crystal structure |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010720667.4A CN111856656B (en) | 2020-07-24 | 2020-07-24 | Four-channel drop filter with photonic crystal structure |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN111856656A CN111856656A (en) | 2020-10-30 |
| CN111856656B true CN111856656B (en) | 2022-12-23 |
Family
ID=72950223
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010720667.4A Active CN111856656B (en) | 2020-07-24 | 2020-07-24 | Four-channel drop filter with photonic crystal structure |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111856656B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114325935B (en) * | 2021-12-08 | 2024-04-16 | 南京邮电大学 | Non-magnetic photon crystal non-reciprocal double-channel narrow-band filter |
| CN114690325B (en) * | 2022-04-28 | 2023-11-03 | 桂林电子科技大学 | Photonic crystal tunable multichannel filter oriented to network on optical sheet |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1846156A (en) * | 2003-08-29 | 2006-10-11 | 独立行政法人科学技术振兴机构 | Two-dimensional photonic crystal multiplexer/demultiplexer |
| CN104568210A (en) * | 2015-01-19 | 2015-04-29 | 北京邮电大学 | Temperature sensor array structure based on tetragonal lattice dielectric post photonic crystal |
| CN107390325A (en) * | 2017-07-14 | 2017-11-24 | 上海大学 | 2 D photon crystal optical router based on nested ring cavity structure |
| CN108646442A (en) * | 2018-05-08 | 2018-10-12 | 南京邮电大学 | Four-way THz wave select switch based on magnetic photonic crystal |
| CN109655968A (en) * | 2019-01-30 | 2019-04-19 | 上海大学 | Path filter under a kind of four-way applied to coarse wavelength division multiplexing systems |
| CN209560136U (en) * | 2019-01-17 | 2019-10-29 | 兰州交通大学 | A kind of eight channel wavelength division multiplexers based on photonic crystal |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6873777B2 (en) * | 2003-03-10 | 2005-03-29 | Japan Aviation Electronics Industry Limited | Two-dimensional photonic crystal device |
| CN104267462B (en) * | 2014-08-21 | 2017-06-30 | 南京邮电大学 | Ring cavity structure THz wave photon crystal filter |
| CN105449321A (en) * | 2015-12-02 | 2016-03-30 | 中国计量学院 | Multi-channel terahertz wave filter |
| CN108333678A (en) * | 2017-12-12 | 2018-07-27 | 西南科技大学 | Magnetic control cavity switches type ROADM based on 2 D photon crystal |
| CN108663748B (en) * | 2018-05-09 | 2019-12-06 | 上海大学 | Dual-channel drop filter based on single line defect resonant cavity |
-
2020
- 2020-07-24 CN CN202010720667.4A patent/CN111856656B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1846156A (en) * | 2003-08-29 | 2006-10-11 | 独立行政法人科学技术振兴机构 | Two-dimensional photonic crystal multiplexer/demultiplexer |
| CN104568210A (en) * | 2015-01-19 | 2015-04-29 | 北京邮电大学 | Temperature sensor array structure based on tetragonal lattice dielectric post photonic crystal |
| CN107390325A (en) * | 2017-07-14 | 2017-11-24 | 上海大学 | 2 D photon crystal optical router based on nested ring cavity structure |
| CN108646442A (en) * | 2018-05-08 | 2018-10-12 | 南京邮电大学 | Four-way THz wave select switch based on magnetic photonic crystal |
| CN209560136U (en) * | 2019-01-17 | 2019-10-29 | 兰州交通大学 | A kind of eight channel wavelength division multiplexers based on photonic crystal |
| CN109655968A (en) * | 2019-01-30 | 2019-04-19 | 上海大学 | Path filter under a kind of four-way applied to coarse wavelength division multiplexing systems |
Non-Patent Citations (1)
| Title |
|---|
| 光子晶体矩形波形滤波器和大角度光分束器的实现;胡萍;《南昌大学高校教师在职攻读硕士学位研究生学位论文》;20091105;全文 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN111856656A (en) | 2020-10-30 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP3524336B2 (en) | Optical device | |
| US6643421B1 (en) | Wavelength-slicing architecture for wavelength demultiplexing using micro-ring resonators | |
| CN111856656B (en) | Four-channel drop filter with photonic crystal structure | |
| JP4822141B2 (en) | Wavelength group optical demultiplexer, wavelength group optical multiplexer, and wavelength group optical selective switch | |
| EP2095552B1 (en) | Method and device for hitless tunable optical filtering | |
| US6754411B2 (en) | Mach-zehnder based filter demultiplexers and method | |
| CN101533126B (en) | Photonic crystal wavelength division multiplexer and design method thereof | |
| CA2245054C (en) | Multi-pass optical filter | |
| CN101252407B (en) | Wave decomposing multiplexer based on two-dimension photon crystal | |
| CN101246237B (en) | Multi-cavity cascade-connection photon crystal multicenter wave filter | |
| EP2092673B1 (en) | Method and device for hitless tunable optical filtering | |
| CN109655968B (en) | Four-channel down-path filter applied to coarse wavelength division multiplexing system | |
| CN108333678A (en) | Magnetic control cavity switches type ROADM based on 2 D photon crystal | |
| CN108061927B (en) | Photonic crystal wavelength division mode division hybrid multiplexing demultiplexer and method | |
| US20050053332A1 (en) | Integrateable band filter using waveguide grating routers | |
| CN114690325B (en) | Photonic crystal tunable multichannel filter oriented to network on optical sheet | |
| Mehdizadeh et al. | All optical 8-channel wavelength division demultiplexer based on photonic crystal ring resonators | |
| JPH04178613A (en) | Variable wavelength filter | |
| CN113568089B (en) | Mode division multiplexer based on multicore annular photon lantern | |
| CN108663748B (en) | Dual-channel drop filter based on single line defect resonant cavity | |
| JP2001051140A (en) | Optical multiplexer/demultiplexser having three waveguides | |
| CN114637072B (en) | Shallow etching multimode interference coupling multichannel flat-top type wavelength division multiplexing receiver | |
| JP5798096B2 (en) | Arrayed waveguide grating router | |
| Arianfard et al. | Integrated photonic coupled Sagnac loop reflectors for flat-top wavelength interleaving and switching | |
| Irshid et al. | A WDM cross-connected star multihop optical network |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |