CN114563845A - Asymmetric directional coupler, adjustable mode generator and optical circulator - Google Patents
Asymmetric directional coupler, adjustable mode generator and optical circulator Download PDFInfo
- Publication number
- CN114563845A CN114563845A CN202210243401.4A CN202210243401A CN114563845A CN 114563845 A CN114563845 A CN 114563845A CN 202210243401 A CN202210243401 A CN 202210243401A CN 114563845 A CN114563845 A CN 114563845A
- Authority
- CN
- China
- Prior art keywords
- waveguide
- output waveguide
- output
- directional coupler
- asymmetric directional
- 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.)
- Pending
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
-
- 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
- G02B6/2934—Fibre ring resonators, e.g. fibre coils
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Optical Integrated Circuits (AREA)
Abstract
The invention provides an asymmetric directional coupler, which comprises a substrate, wherein top layer silicon is arranged on the substrate, the top layer silicon comprises a first port, a coupling area, a first output waveguide and a second output waveguide, one end of the coupling area is connected with the first port, the other end of the coupling area is connected with the first output waveguide and the second output waveguide, a phase change material layer covers the coupling area, the coupling area is divided into N multiplied by M rectangular units, a first aperiodic perforating array meeting a preset first output target is formed by adjusting the states of the rectangular units, and the first output target refers to the sum of transmittances of the first output waveguide and the second output waveguide; the asymmetric directional coupler provided by the invention has the advantages of small size, easiness in processing and stable performance, and can realize the regulation and control of a light propagation path.
Description
Technical Field
The invention belongs to the technical field of micro-nano optoelectronic components, and particularly relates to an asymmetric directional coupler, an adjustable mode generator and an optical circulator.
Background
Silicon photonics is a very promising optical interconnect platform due to its compatibility with existing Complementary metal-oxide semiconductor (CMOS) technologies and dense integration technologies. Photonic Integrated Circuits (PICs) have also grown enormously over the past decade.
Today, the most advanced photonic integrated circuits have been able to integrate hundreds or thousands of optical devices. Among them, the optical switch is an indispensable constituent element for dynamic routing of light in different paths. The on-chip optically controllable devices are usually implemented based on electro-optical or thermo-optical effects, both of which are implemented by using electricity or heat to act on the waveguide, thereby slightly changing the refractive index of the waveguide to implement the switching, i.e. switching, of the optical transmission channel. However, such optical switching mechanisms are volatile, require continuous energy to maintain the switching state, and are designed to have complicated processes and large sizes, which are not suitable for large-scale integration.
In order to expand data capacity, Mode Division Multiplexing (MDM) technology is widely focused. The mode generator is, among other things, an indispensable component that excites and switches different modes of the carrier wave in the optical waveguide. In addition, an Optical isolator (Optical isolator) and an Optical circulator (Optical circulator) are nonreciprocal devices that can make light propagate in one direction. Among them, the optical isolator is a dual port device, a single line of light, and plays a vital role in preventing unnecessary back reflection and interaction of light. Similarly, an optical circulator is a multi-port device, which is a roundabout of optical paths, where light is routed in a non-reciprocal manner at each input port to an output port. They are all indispensable components in optical networks. Although pattern generators and optical circulators have been reported, most of them have the disadvantages of being uncontrollable, large in size, and complicated in design method.
In recent years, germanium antimony tellurium compound optical phase change materials, such as Ge, integrated on silicon waveguides2Sb2Te5(GST) and Ge2Sb2Se4Te1(GSST), demonstrating the feasibility of designing a tunable device. Andthe difference of the electro-optic or thermo-optic effect of utilizing electricity or heat to act on the waveguide to slightly change the refractive index is that the germanium antimony tellurium compound not only can greatly change the refractive index of the waveguide and is beneficial to designing a small-sized optical regulation device, but also the phase change is nonvolatile and does not need external continuous energy to maintain the state of the device. It can be seen that implementing a controllable device based on phase change materials is a very promising solution.
In view of this, the design of the adjustable mode generator and the circulator based on the phase-change material has great significance for solving the problems that the existing device is not adjustable, the size is large and the design method is complex.
Disclosure of Invention
The technical problem to be solved by the invention is to overcome the defects of complex process, volatility, large size and the like of the existing optical switch, and provide a phase-change material-based silicon-based asymmetric directional coupler optimized by using a Direct-binary-search (DBS) algorithm.
In order to achieve the above object, an asymmetric directional coupler according to an embodiment of the present invention includes a substrate, where the substrate is provided with a top layer silicon, the top layer silicon includes a first port, a coupling region, a first output waveguide, and a second output waveguide, one end of the coupling region is connected to the first port, and the other end of the coupling region is connected to the first output waveguide and the second output waveguide, the coupling region is covered with a phase change material layer, the coupling region is divided into N × M rectangular units, and a first aperiodic perforation array meeting a predetermined first output target is formed by adjusting states of the rectangular units, where the first output target is a sum of transmittances of the first output waveguide and the second output waveguide.
Preferably, the coupling region includes an upper waveguide, a waveguide gap and a lower waveguide, the first port, the upper waveguide and the first output waveguide are sequentially connected, the lower waveguide is connected with the second output waveguide, the phase change material layer covers the top surface of the lower waveguide, and the waveguide gap is formed between the upper waveguide and the lower waveguide.
Preferably, the phase change material layer is a GSST material.
Preferably, at least one of the first output waveguide and the second output waveguide is a curved waveguide.
Preferably, the substrate thickness is 3 μm, the top silicon thickness is 220nm, the coupling region length is 10 μm, the upper waveguide width is 380nm, the upper waveguide is divided into 4 × 100 first rectangular units, each first rectangular unit has a size of 95nm × 100nm and a depth of 220nm, and no hole is formed in the initial state; the widths of the lower waveguide and the phase change material layer are 350nm, the thickness of the phase change material layer is 40nm, the phase change material layer is divided into 4 x 100 second rectangular units, the size of each second rectangular unit is 87.5nm x 100nm, the depth of each second rectangular unit is 40nm, and holes are not punched in the initial state; the waveguide pitch is divided into 2 × 100 third rectangular units, each of which has a size of 100nm × 100nm, a depth of 220nm, and is initially perforated.
The invention also provides an adjustable mode generator, which comprises the asymmetric directional coupler, a mode division multiplexer optimization area and a third output waveguide, wherein one end of the mode division multiplexer optimization area is respectively connected with the first output waveguide and the second output waveguide, the other end of the mode division multiplexer optimization area is connected with the third output waveguide, the mode division multiplexer optimization area is divided into X multiplied by Y fourth rectangular units, a non-periodic second perforation array meeting a preset second output target is formed by adjusting the states of the fourth rectangular units, and the second output target is the sum of transmittances of two output different modes in the third output waveguide.
Preferably, the width of the third output waveguide is 900nm, and the two different modes are TE bands from 1540nm to 1560nm0Mode and TE band from 1540nm to 1560nm1Mode(s).
Preferably, the size of the optimized area is 2400nm × 3000nm, the mode division multiplexer optimized area is divided into 24 × 30 fourth rectangular units with the size of 100nm × 100nm, and the distance between the connection ends of the first output waveguide and the second output waveguide and the mode division multiplexer optimized area is 1635 nm.
The invention also provides an optical circulator which comprises the asymmetric directional coupler, wherein a plurality of asymmetric directional couplers are in an annular array, and the first output waveguide of one asymmetric directional coupler is connected with the second output waveguide of the adjacent asymmetric directional coupler.
Preferably, the annular optical mode is TE wave band from 1540nm to 1560nm0Mode(s).
The invention has the advantages of small product size, easy processing, stable performance, low-loss transmission realization and capability of solving the problems of uncontrollable regulation, larger size and complex design method of the existing optical switch.
Drawings
Fig. 1 is a schematic structural diagram of an asymmetric directional coupler according to an embodiment of the present invention.
Fig. 2 is a schematic diagram of an initial structure of the embodiment shown in fig. 1.
FIG. 3 shows the parameter scanning result of the embodiment shown in FIG. 1.
Fig. 4 is a schematic diagram of a two-dimensional plane structure of the embodiment shown in fig. 1.
Fig. 5 is a transmission spectrum of the embodiment shown in fig. 1.
Fig. 6 is a schematic structural diagram of an adjustable mode generator according to an embodiment of the invention.
Fig. 7 is a schematic diagram of a two-dimensional plane structure of the embodiment shown in fig. 6.
Fig. 8 is a schematic diagram of an initial structure of the optimization area of the mode division multiplexer in the embodiment shown in fig. 6.
Fig. 9 is a transmission spectrum of the embodiment shown in fig. 6.
Fig. 10 is a schematic structural diagram of an optical circulator according to an embodiment of the present invention.
Fig. 11 is a schematic diagram of a two-dimensional plane structure of the embodiment shown in fig. 10.
Fig. 12 is a transmission spectrum of the embodiment shown in fig. 10.
In the figure, 1, the first port; 2. a coupling region; 21. an upper waveguide; 22. a lower waveguide; 221. a second rectangular unit; 23. a waveguide gap; 231. a third rectangular unit; 24. a phase change material layer; 3. a first output waveguide; 4. a second output waveguide; 5. a mode division multiplexer optimization area; 51. a fourth rectangular unit; 6. a third output waveguide; 7. a second port; 8. a third port; 9. a fourth port; 10. a fifth port; 11. a first asymmetric directional coupler; 12. a second asymmetric directional coupler; 13. a third asymmetric directional coupler; 14. a fourth asymmetric directional coupler; 15. a first curved waveguide; 16. a second curved waveguide; 17. a third curved waveguide; 18. and a fourth curved waveguide.
Detailed Description
The technical scheme of the invention is further described in detail by combining the drawings and the specific embodiments:
example one
Referring to fig. 1 to 5, the asymmetric directional coupler provided by the present invention includes a substrate 100, the substrate 100 is provided with a top layer silicon, the top layer silicon includes a first port 1, a coupling region 2, a first output waveguide 3 and a second output waveguide 4, one end of the coupling region 2 is connected to the first port 1, the other end is connected to the first output waveguide 3 and the second output waveguide 4, the coupling region 2 is covered with a phase change material layer 24, the coupling region 2 is divided into N × M rectangular units, and by adjusting states of the rectangular units, a non-periodic first punch array satisfying a predetermined first output target is formed, where the first output target is a sum of transmittances of the first output waveguide 3 and the second output waveguide 4.
More specifically, the coupling region 2 includes an upper waveguide 21, a lower waveguide 22 and a waveguide gap 23, the first port 1, the upper waveguide 21 and the first output waveguide 3 are sequentially connected and maintain the same width, the lower waveguide 22 is connected with the second output waveguide 4 and maintain the same width, the waveguide gap 23 is formed between the upper waveguide 21 and the lower waveguide 22, and the phase change material layer 24 covers the top surface of the lower waveguide 22.
More specifically, the phase change material layer 24 is a GSST material.
More specifically, at least one of the first output waveguide 3 and the second output waveguide 4 is a curved waveguide in order to decouple and thereby reduce crosstalk.
More specifically, the asymmetric directional coupler is designed on a Silicon on insulator platform (Silicon on insulator)or, SOI) with a top silicon thickness of 220nm, a substrate 100 with a silica thickness of 3 μm, an upper cladding of air, and a length W of said coupling region 2410 μm, the width W of the upper waveguide 211380nm, the upper waveguide 21 is divided into 4 × 100 first rectangular units, each of which has a size of 95nm × 100nm, a depth of 220nm, and is initially non-perforated; width W of the lower waveguide 22 and the phase change material layer 242350nm, the thickness of the phase change material layer 24 is 40nm, the phase change material layer 24 is divided into 4 × 100 second rectangular units 221, each second rectangular unit 221 is 87.5nm × 100nm in size, 40nm in depth, and the initial state is not perforated; width W of said waveguide gap 233At 200nm, the waveguide gap 23 is divided into 2 × 100 third rectangular units 231, each third rectangular unit 231 having a size of 100nm × 100nm and a depth of 220nm, and is initially perforated.
Compared with the traditional method for designing an optical device, the intelligent algorithm is used, the optimization can be performed by depending on a physical model less under high degree of freedom, and the design of a device with a small size and a complex structure is facilitated. Before optimization using the direct binary search algorithm, the coupling area 2 is divided into several rectangular units, each having two material states, perforated, i.e. the rectangular units are filled with air, and non-perforated, i.e. the rectangular units are filled with silicon. Each rectangular unit state is determined by an algorithm to satisfy an objective function, specifically: an objective function reflecting the device performance is set in a direct binary search algorithm, then the objective function values of two states of each rectangular unit are calculated in sequence by using the algorithm, and then the state when the objective function values are improved is reserved.
When rectangular cells are computed using the direct binary search algorithm, all cells are computed using the row-wise computation and the column-wise computation in alternation. And traversing all the units once is called as one iteration, and comparing the objective function values after the last iteration after multiple iterations, wherein the change value of the objective function values of two times is lower than 0.1%, the objective function is converged, and the algorithm is stopped. The calculation by rows refers to the calculation from left to right in sequence in the horizontal direction and from top to bottom in the vertical direction; the calculation by column means that the vertical direction is from top to bottom, and the horizontal direction is from left to right.
The phase change material layer 24 on the asymmetric directional coupler is subjected to reversible phase change rapidly through light or electricity, and the refractive index of the waveguide is influenced, so that the light propagation path is regulated. Therefore, before the device is completed, the asymmetric directional coupler needs to be designed, and when the asymmetric directional coupler is optimized, an objective function reflecting the performance of the device is set as the sum of the transmittances of the two output waveguides.
Since the direct binary search algorithm is a search algorithm, premature local convergence is easily caused, and thus, the optimization result is not ideal. To overcome this problem, in optimizing the asymmetric directional coupler, the initial configuration as shown in fig. 2 is manually set, i.e., the initial state of all the first rectangular cells on the upper waveguide 21 is non-perforated, the lower waveguide 22 is non-perforated, the initial state of all the third rectangular cells 231 on the waveguide gap 23 is perforated, and the initial state of all the second rectangular cells 221 on the phase change material layer 24 is non-perforated. In order to obtain excellent initial structure parameters, certain optimization of the initial structure parameters is required.
First of all, the width of the waveguide gap 23 is W3Set to 200nm, coupling length W 410 μm, the width of the phase change material layer 24 covering the surface of the lower waveguide 22 is identical to the width of the lower waveguide 22, and the thickness of the phase change material layer 24 is 40 nm. With these parameters determined, the width W of the upper waveguide 21 is measured1And width parameter W of lower waveguide 222Scanning is carried out, and an initial structure with better performance is optimized. The results of the parametric scan are shown in FIG. 3, and it can be found that when the width W of the upper waveguide 21 is large1About 380nm, the width W of the lower waveguide 222When the wavelength is about 350nm, the GSST of the phase change material layer 24 is adjusted to be an amorphous state, and light is better coupled into the lower waveguide 22 due to phase matching; the GSST of the phase change material layer 24 is adjusted to be crystalline, and light still propagates on the upper waveguide 21 due to poor coupling efficiency due to phase mismatch. The width W of the upper waveguide 21 is finally selected in consideration of trade-off1380nm, width W of lower waveguide 222350nm, width of the phase change material layer 24 on the surface of the lower waveguide 22The degree is also 350 nm.
In addition, since the upper and lower waveguides generate a coupling effect, the distance between the two waveguides needs to be increased at the output position, the coupling effect is suppressed, and the propagation of light in the waveguides is not affected. Therefore, at least one of the output portions where the upper and lower waveguides are connected needs to be shaped into a curved waveguide, that is, at least one of the first output waveguide 3 and the second output waveguide 4 is a curved waveguide.
After obtaining the manually designed initial structure, the coupling region 2 needs to be divided into N × M rectangular units, where N and M are integers, and the rectangular side length setting also needs to take into consideration workability. For this, the coupling region 2 is divided into three sections, totaling 10 × 100 rectangular units, including 4 × 100 first rectangular units of the upper waveguide 21 section, 4 × 100 second rectangular units 221 of the phase change material layer 24 section, and 2 × 100 third rectangular units 231 of the waveguide gap 23 section. Each rectangular unit has two material states, namely, a punched state and a non-punched state, wherein the punched state is that the rectangular unit is filled with air, and the non-punched state is that the rectangular unit is filled with silicon.
The upper waveguide 21 is divided into 4 × 100 rectangular units, each first rectangular unit having a size of 95nm × 100nm and a depth of 220nm, and is initially non-perforated; because the invention changes the effective refractive index to realize the regulation function through the phase-change material layer 24 with the thickness of 40nm, the lower waveguide 22 does not divide a rectangular unit and does not perforate; the phase change material layer 24 is divided into 4 × 100 second rectangular units 221, each second rectangular unit 221 has a size of 87.5nm × 100nm and a depth of 40nm, penetrates only the phase change material layer 24, and is initially non-perforated; the waveguide gap 23 is divided into 2 × 100 third rectangular units 231, each third rectangular unit 231 having a size of 100nm × 100nm and a depth of 220nm, and is initially perforated.
The direct binary search algorithm optimizes a total of 10 × 100 rectangular units on the initial structure. First, the algorithm selects the rectangular cells in the first row and the first column, and calculates the performance of the two states of punching and non-punching by using a Finite difference time domain method (FDTD). The performance decision is determined by an objective function set inside the algorithm, called Figure of merit (FOM), defined as:
FOM＝TA-GSST+TC-GSST
in the formula, TA-GSSTThe transmittance of the second output waveguide 4 is 1540nm to 1560nm in the wavelength band when the GSST material is amorphous; t isC-GSSTThe transmittance of the first output waveguide 3 when the GSST material is crystalline is 1540nm to 1560nm in the wavelength band.
And then line-wise scan to the last rectangular cell, which is called an iteration. The next iteration scans in the same manner column-wise to the last rectangular cell. And (4) alternately scanning and optimizing by rows and columns, and iterating for multiple times until the FOM value after two iterations is changed within 0.1%, so that the algorithm is converged and the device performance is stable. The calculation by rows means that the calculation is sequentially from left to right in the horizontal direction and from top to bottom in the vertical direction; the calculation by column means that the vertical direction is from top to bottom, and the horizontal direction is from left to right.
FIG. 4 is a schematic diagram showing a two-dimensional plane structure of an asymmetric directional coupler optimized by using a direct binary search algorithm, FIG. 5 is a schematic diagram showing a transmission spectrum of the asymmetric directional coupler, in a bandwidth range of 1540nm to 1560nm, and TE when GSST is in an amorphous state0The mode crosstalk is lower than-16.4 dB in the first output waveguide 3 and the insertion loss is less than 0.6dB in the second output waveguide 4; when GSST is crystalline, TE0The mode insertion loss in the first output waveguide 3 is less than 1.0dB, and the crosstalk in the second output waveguide 4 is lower than-16.0 dB;
the specific working principle is as follows: TE with bandwidth of 1540nm to 1560nm0Mode light is injected into the first port 1, the phase change of the GSST is controlled by light or electricity, when the GSST is in an amorphous state, the input light is transmitted from the second output waveguide 4 with high efficiency, and the crosstalk in the first output waveguide 3 is low; when the GSST is crystalline, the input light is efficiently transmitted through the first output waveguide 3 and the crosstalk at the second output waveguide 4 is low. The transmission spectrum simulated by the asymmetric directional coupler provided by the embodiment also shows the excellent performance, and compared with an optical switch designed by other methods, the asymmetric directional coupler has the advantages of good performance, small size, easiness in processing and the like.
Example two
Referring to fig. 6-9, the present embodiment provides a controllable mode generator, including the above-mentioned asymmetric directional coupler, a mode division multiplexer optimization area 5 and a third output waveguide 6, where one end of the mode division multiplexer optimization area 5 is connected to the first output waveguide 3 and the second output waveguide 4, respectively, and the other end is connected to the third output waveguide 6, the mode division multiplexer optimization area 5 is divided into X × Y fourth rectangular units 51, and a non-periodic second puncturing array meeting a predetermined second output target is formed by adjusting states of the fourth rectangular units 51, where the second output target is a sum of transmittances of two output different modes in the third output waveguide 6.
More specifically, the two different modes are TE bands from 1540nm to 1560nm0Mode and TE band from 1540nm to 1560nm1Mode, the width of the third output waveguide 6 is 900 nm.
More specifically, the size of the mode division multiplexer optimization area 5 is 2400nm × 3000nm, the mode division multiplexer optimization area 5 is divided into 24 × 30 fourth rectangular units 51 with 100nm × 100nm, and the distance W between the connection ends of the first output waveguide 3 and the second output waveguide 4 and the mode division multiplexer optimization area 551635 nm.
In the present embodiment, the first output waveguide 3 and the second output waveguide 4 are both curved waveguides.
The mode division multiplexer optimization area 5 is also designed by using a direct binary search algorithm, for example, fig. 8 shows an initial structure of the mode division multiplexer optimization area 5, the size of the mode division multiplexer optimization area 5 is 2400nm × 3000nm, the mode division multiplexer optimization area is divided into 24 × 30 fourth rectangular units 51 with 100nm × 100nm, each fourth rectangular unit 51 has two material states, namely, a punched state and a non-punched state, the punched state is that the fourth rectangular unit 51 is filled with air, and the non-punched state is that the fourth rectangular unit 51 is filled with silicon. The direct binary search algorithm optimizes a total of 24 × 30 rectangular units on the initial structure. The decision of performance is determined by an objective function arranged inside the algorithm, defined as:
in the formula (I), the compound is shown in the specification,
is at a wavelength of 1540nm to 1560nm, TE0Mode injection from the first output waveguide 3, maintaining TE0The transmittance of the mode at the third output waveguide 6;
is at a wavelength of 1540nm to 1560nm, TE0Mode injection conversion from the second output waveguide 4 to TE1The transmittance of the mode at the third output waveguide 6. The output waveguide width is 900nm, and the TE can be supported without loss0And TE1Propagation of the mode.
The mode generator operates on the principle of generating different modes of light by adjusting the GSST phase change on the asymmetric directional coupler. The method comprises the following specific steps: when TE0The mode light source is injected from the first port 1, and GSST is adjusted to be crystalline state, TE0The mode enters a mode division multiplexer optimization area 5 from a first output waveguide 3 through an asymmetric directional coupler to maintain TE0The mode is output from the third output waveguide 6; when TE0The mode light source is injected from the first port 1, GSST is adjusted to be amorphous state, TE0The mode enters the optimized region 5, TE of the mode division multiplexer from the second output waveguide 4 through the asymmetric directional coupler0Mode conversion to TE1The mode is output from the third output waveguide 6.
FIG. 9 shows the transmission spectrum of the pattern generator provided in this embodiment, when GSST is crystalline, the output TE of the pattern generator0Mode, insertion loss less than 1.5dB, crosstalk less than-13.9 dB; when GSST is amorphous, the mode generator outputs TE1Mode, with insertion loss less than 2.2dB, crosstalk is lower than-14.8 dB. The pattern generator provided by the embodiment can solve the problems that the existing pattern generator is not adjustable and controllable, has large size and is complex in design method.
EXAMPLE III
Referring to fig. 10-12, the present invention also provides an optical circulator, which includes the above-mentioned asymmetric directional coupler, a plurality of asymmetric directional couplers are in a ring array, and the first output waveguide 3 of one of the asymmetric directional couplers is connected to the second output waveguide 4 of the adjacent asymmetric directional coupler.
In this embodiment, the first output waveguide 3 and the second output waveguide 4 are connected to form a curved waveguide, the optical circulator is formed by sequentially connecting four asymmetric directional couplers 11-14 through a first curved waveguide 15, a second curved waveguide 16, a third curved waveguide 17 and a fourth curved waveguide 18 in series, and both ends of each curved waveguide are respectively the same as the width of the connection part.
It can be understood that, according to different use requirements, the optical circulator may be formed by connecting three, four, five or more asymmetric directional couplers in series, and the number of the curved waveguides is increased or decreased accordingly.
The working principle of the optical circulator is that the GSST phase change and TE phase change on the asymmetric directional coupler are adjusted0The mode light sources are output from adjacent ports either clockwise or counterclockwise. The method comprises the following specific steps: when TE0The mode light source is injected from the second port 7, GSST on the first asymmetric directional coupler 11 is in a crystalline state, GSST on the second asymmetric directional coupler 12, the third asymmetric directional coupler 13 and the fourth asymmetric directional coupler 14 is in an amorphous state, and TE is0The mode is output from the third port 8 in the clockwise direction, and so on, TE0The mode light source can circularly and clockwise propagate in the direction of the second port 7, the third port 8, the fourth port 9, the fifth port 10 and the second port 7; when TE0The mode light source is injected from the second port 7, GSST on the first asymmetric directional coupler 11 is in an amorphous state, GSST on the second asymmetric directional coupler 12, the third asymmetric directional coupler 13 and the fourth asymmetric directional coupler 14 is in a crystalline state, and TE is0The pattern is output from the fifth port 10 in the counterclockwise direction, and so on, TE0The mode light source may travel circularly counterclockwise in the direction of the ports second port 7-fifth port 10-fourth port 9-third port 8-second port 7.
FIG. 12 shows the transmission of the optical circulator provided in this embodimentSpectrum of light when TE0Injecting mode into the second port 7, when GSST layer on the first asymmetric directional coupler 11 is crystalline state, and GSST layers of other ports are amorphous state, TE0Mode light circularly and clockwise propagates in the direction of the second port 7, the third port 8, the fourth port 9, the fifth port 10 and the second port 7, the insertion loss is less than 1.2dB, and the crosstalk is lower than-20.0 dB; when TE0Injecting mode into the second port 7, when GSST layer on the first asymmetric directional coupler 11 is amorphous, and GSST layers of other ports are crystalline, TE0The mode light circularly and anticlockwise propagates in the direction of the second port 7, the fifth port 10, the fourth port 9, the third port 8 and the second port 7, the insertion loss is less than 1.2dB, and the crosstalk is lower than-29.4 dB. Compared with devices designed by other methods, the optical circulator provided by the embodiment has the advantages of adjustability, controllability, small size, intelligent design and the like.
The above examples are only for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. An asymmetric directional coupler, characterized by: the phase change optical fiber laser device comprises a substrate, wherein top layer silicon is arranged on the substrate and comprises a first port, a coupling area, a first output waveguide and a second output waveguide, one end of the coupling area is connected with the first port, the other end of the coupling area is connected with the first output waveguide and the second output waveguide, a phase change material layer covers the coupling area, the coupling area is divided into N x M rectangular units, a first aperiodic perforation array meeting a preset first output target is formed by adjusting the states of the rectangular units, and the first output target is the sum of the transmittances of the first output waveguide and the second output waveguide.
2. The asymmetric directional coupler as recited in claim 1, wherein: the coupling region comprises an upper waveguide, a waveguide gap and a lower waveguide, the first port, the upper waveguide and the first output waveguide are sequentially connected, the lower waveguide is connected with the second output waveguide, the phase change material layer covers the top surface of the lower waveguide, and the waveguide gap is arranged between the upper waveguide and the lower waveguide.
3. The asymmetric directional coupler as recited in claim 2, wherein: the phase change material layer is a GSST material.
4. An asymmetric directional coupler according to claim 2 or 3, characterized in that: at least one of the first output waveguide and the second output waveguide is a curved waveguide.
5. The asymmetric directional coupler as recited in claim 4, wherein: the thickness of the substrate is 3 microns, the thickness of the top layer silicon is 220nm, the length of the coupling region is 10 microns, the width of the upper waveguide is 380nm, the upper waveguide is divided into 4 x 100 first rectangular units, the size of each first rectangular unit is 95nm x 100nm, the depth of each first rectangular unit is 220nm, and holes are not punched in the initial state; the widths of the lower waveguide and the phase change material layer are 350nm, the thickness of the phase change material layer is 40nm, the phase change material layer is divided into 4 x 100 second rectangular units, the size of each second rectangular unit is 87.5nm x 100nm, the depth of each second rectangular unit is 40nm, and holes are not punched in the initial state; the waveguide pitch is divided into 2 × 100 third rectangular units, each of which has a size of 100nm × 100nm, a depth of 220nm, and is initially perforated.
6. An adjustable mode generator, comprising: the asymmetric directional coupler of any one of claims 1-5, a mode division multiplexer optimization area and a third output waveguide, wherein one end of the mode division multiplexer optimization area is connected to the first output waveguide and the second output waveguide respectively, and the other end of the mode division multiplexer optimization area is connected to the third output waveguide, the mode division multiplexer optimization area is divided into X X Y fourth rectangular units, and a non-periodic second puncturing array meeting a predetermined second output target is formed by adjusting the states of the fourth rectangular units, and the second output target is the sum of transmittances of two output different modes in the third output waveguide.
7. The controllable pattern generator of claim 6, wherein: the two different modes are TE wave bands from 1540nm to 1560nm0Mode and TE band from 1540nm to 1560nm1Mode, the width of the third output waveguide is 900 nm.
8. The controllable pattern generator of claim 6, wherein: the size of the mode division multiplexer optimization area is 2400nm multiplied by 3000nm, the mode division multiplexer optimization area is divided into 24 multiplied by 30 fourth rectangular units with the size of 100nm multiplied by 100nm, and the distance between the connection ends of the first output waveguide and the second output waveguide and the mode division multiplexer optimization area is 1635 nm.
9. An optical circulator, comprising: comprising an asymmetric directional coupler according to any of claims 1 to 5, a plurality of asymmetric directional couplers in a ring array, a first output waveguide of one said asymmetric directional coupler being connected to a second output waveguide of an adjacent asymmetric directional coupler.
10. The optical circulator of claim 9, wherein: the annular optical mode is TE wave band from 1540nm to 1560nm0Mode(s).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210243401.4A CN114563845A (en) | 2022-03-11 | 2022-03-11 | Asymmetric directional coupler, adjustable mode generator and optical circulator |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210243401.4A CN114563845A (en) | 2022-03-11 | 2022-03-11 | Asymmetric directional coupler, adjustable mode generator and optical circulator |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN114563845A true CN114563845A (en) | 2022-05-31 |
Family
ID=81719809
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210243401.4A Pending CN114563845A (en) | 2022-03-11 | 2022-03-11 | Asymmetric directional coupler, adjustable mode generator and optical circulator |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114563845A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115308847A (en) * | 2022-07-11 | 2022-11-08 | 宁波大学 | Dual-mode interference 2X 2 optical waveguide switch based on phase change material |
| CN115857098A (en) * | 2023-03-02 | 2023-03-28 | 北京航空航天大学 | Optical circulator on silicon substrate |
| CN116224498A (en) * | 2023-05-09 | 2023-06-06 | 之江实验室 | On-chip switch, forming method thereof and optical communication element |
-
2022
- 2022-03-11 CN CN202210243401.4A patent/CN114563845A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115308847A (en) * | 2022-07-11 | 2022-11-08 | 宁波大学 | Dual-mode interference 2X 2 optical waveguide switch based on phase change material |
| CN115308847B (en) * | 2022-07-11 | 2023-10-24 | 宁波大学 | Dual-mode interference 2X 2 optical waveguide switch based on phase change material |
| CN115857098A (en) * | 2023-03-02 | 2023-03-28 | 北京航空航天大学 | Optical circulator on silicon substrate |
| CN116224498A (en) * | 2023-05-09 | 2023-06-06 | 之江实验室 | On-chip switch, forming method thereof and optical communication element |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN114563845A (en) | Asymmetric directional coupler, adjustable mode generator and optical circulator | |
| CN106324865A (en) | Phase change material-based three-dimensional integrated optical switch | |
| KR20050093764A (en) | Optical switch, optical modulator, and variable wavelength filter | |
| CN103091783B (en) | Tunable array waveguide grating based on liquid crystal waveguides | |
| CN114326164A (en) | 2X 2 optical waveguide switch based on phase change material and preparation method thereof | |
| CN112946967A (en) | 2X 4 optical waveguide switch based on phase change material | |
| CN113625392A (en) | 4X 4 optical switch array based on organic-inorganic hybrid integration | |
| CN110737052B (en) | Reconfigurable arbitrary optical mode exchanger based on micro-ring resonator | |
| CN113985522B (en) | Micro-ring optical switch based on silicon-silicon nitride three-dimensional integration | |
| CN217561775U (en) | Asymmetric directional coupler, adjustable mode generator and optical circulator | |
| Hang et al. | Compact, highly efficient, and controllable simultaneous 2× 2 three-mode silicon photonic switch in the continuum band | |
| CN102636888A (en) | Electro-optic tuning multi-wavelength FIR (Finite Impulse Response) filter and all-level voltage determining method | |
| CN103941336A (en) | Three-port router based on planar optical waveguide technology and manufacturing method thereof | |
| CN116088245A (en) | Based on phase change material Sb 2 Se 3 Is a non-volatile reconfigurable compact all-optical logic gate | |
| CN114924351B (en) | Polarization converter and design method | |
| CN111025467A (en) | Tunable optical differentiator based on silicon-based metamaterial | |
| CN202133846U (en) | Tunable optical power splitter based on two-dimensional liquid crystal photonic crystal | |
| CN114994835A (en) | Optical network on full-mixed wave chip and design method | |
| CN115390193A (en) | Multimode-switching 1X 3 optical switch based on phase-change material and preparation method thereof | |
| Luo et al. | Inverse design of deformed Sb 2 Se 3 stripes in silicon waveguide for reconfigurable mode converters | |
| CN114839715B (en) | Non-volatile phase change reconfigurable silicon-based mode converter and manufacturing method thereof | |
| Jin et al. | Design of cyclic arrayed waveguide grating with distributed waveguide directions for uniform loss | |
| CN114895502B (en) | Repetition frequency large-range adjustable silicon nitride micro-optical comb array based on optical switch switching network | |
| CN118244424A (en) | Mode change-over switch based on phase change material and reverse design | |
| Ho et al. | Design and optimization of optical mode exchange based on cascaded multimode interferences |
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 |