CN114326164A - 2X 2 optical waveguide switch based on phase change material and preparation method thereof - Google Patents
2X 2 optical waveguide switch based on phase change material and preparation method thereof Download PDFInfo
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- CN114326164A CN114326164A CN202111573963.7A CN202111573963A CN114326164A CN 114326164 A CN114326164 A CN 114326164A CN 202111573963 A CN202111573963 A CN 202111573963A CN 114326164 A CN114326164 A CN 114326164A
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Abstract
The invention discloses a 2X 2 optical waveguide switch based on a phase change material and a preparation method thereof. A 2 x 2 optical switch unit waveguide structure is arranged on a substrate, two waveguides are in axial symmetry distribution and comprise two input ports and two output ports, and a coupling area is arranged in the middle; preparing uniform hundred-nanometer Ge with the same components as the target material in the coupling region by adopting a pulse laser deposition method2Sb2Se4Te1A film. The switch unit is controlled by a phase-change material covered on the waveguide of the coupling area, the functions of double-channel selection input, double-channel gating and mode switching can be completed on a transverse electric base mode by switching the phase state of the phase-change material, the function of inputting and outputting at the same side port by the same side port is met on the transverse magnetic base mode, and the switch unit has the characteristics of high extinction ratio, small size and high switching rate.
Description
Technical Field
The invention belongs to the technical field of photoelectrons, and particularly relates to a 2X 2 optical waveguide switch based on a phase change material and a preparation method thereof.
Background
With the development of the technical fields of virtual reality, augmented display, cloud computing, big data, artificial intelligence and the like, higher requirements are put forward on the communication capacity, and a new multiplexing technology is found to become a new research hotspot in the field of optical communication. The spatial dimension is used as a new resource for information bearing, new changes are brought to the network technology, the physical dimension and the information capacity of the communication network are increased by multiplexing of the spatial dimension, and the multiplexing technology is a multiplexing technology which is urgently to be developed and utilized. Spatial mode multiplexing, referred to as "mode division multiplexing" for short, is one of spatial dimension multiplexing techniques, and provides a plurality of signal channels for each operating wavelength by using orthogonal spatial modes, so that the transmission capacity of optical communication is significantly improved. In order to be able to build an MDM network on a silicon chip, a mode multiplexer/demultiplexer, a mode filter, a mode order converter, a dual-mode power divider, a reconfigurable mode multiplexing switch, etc. are basic devices for building the multiplexing network. The reconfigurable mode multiplexing switch is one of the most basic devices, can realize the switching of data and signals in a multi-mode channel, and is an essential part for constructing a more flexible and effective MDM network and realizing the functions of a silicon chip all-optical network.
An optical switch is a core unit for mode multiplexing and data exchange, and at present, a silicon-based optical waveguide switch is mainly of a Mach-Zehnder interferometer type (see the literature: Lin Y, Zhou T, Hao J, et al. General architecture for on-chip optical space and mode switching [ J ]. Optica, 2018, 5(2): 180.) based on the principle of optical interference, and mainly forms a phase difference through refractive index changes caused by applying voltage to an interference arm through the electro-optical modulation. However, the refractive index modulation is weak, which causes the device to have an oversized size and a state requiring continuous voltage maintenance, so that the device has volatility.
With the exploration of optical switching devices, optical switches based on phase change materials are gradually emerging. The phase-change material is covered on the waveguide to form a composite waveguide, the phase-change material can perform reversible phase change in a crystalline state and an amorphous state, and a great refractive index difference can be formed before and after the phase change to change the propagation path of the optical signal. Most of the current common 2 × 2 optical switches are mechanical, and have large volume, large insertion loss and unstable optical path switching. Although the conventional 2X 2 optical switch based on phase change material solves these problems, the coupling region is designed based on three waveguide coupling (see the literature: Zhang Q, Zhang Y, Li J, et al. Broadband and non-volatile optical switching materials: beyond the structural configuration-of-polymer [ J ]. Optics Letters, 2018, 43(1):94.), and the phase change material is covered on the intermediate waveguide, which increases the experimental difficulty of the device. Also, since the input ports of such optical switching devices currently under study only support input of a single transverse electric fundamental mode (TE0) or transverse magnetic fundamental mode (TM0), the mixed mode input for TE0 and TM0 cannot form a switching effect, limiting the application of such switches.
Disclosure of Invention
The invention provides a phase-change material-based 2X 2 optical waveguide switch and a preparation method thereof aiming at the defects of the existing 2X 2 waveguide multiplexing type optical switch in the aspects of preparation and tuning, wherein the optical switch structure is composed of two waveguides and a phase-change film deposited on the waveguides, and the function of dual-channel selective input, dual-channel gating and mixed mode separation is realized by changing the phase state of the phase-change material on the composite waveguide, and the optical switch has the characteristics of high extinction ratio, small size, high switching speed and the like.
The technical scheme for realizing the aim of the invention is a preparation method of a 2X 2 optical waveguide switch based on a phase change material, which comprises the following steps:
(1) preparation of waveguide structures
In SiO2Covering a photoresist on a substrate material, and exposing a substrate by adopting a focused electron beam to obtain a device structure shape, wherein the device structure is formed by axially symmetrically distributing two waveguides, two ends of each waveguide are bent, the middle of each waveguide is linear, the width of each waveguide is 100-800 nanometers, and the distance between the linear sections of the two waveguides is 100-500 nanometers; etching the substrate by adopting a reactive ion etching platform to obtain a waveguide structure with two input ports and two output ports with the height of 100-800 nanometers and a coupling region in the middle;
(2) integration of phase change materials
Carrying out photoresist spin coating on the waveguide structure obtained in the step (1), carrying out electron beam exposure on a coupling area of the waveguide structure, and then depositing Ge with the thickness of 10-300 nanometers on the coupling area of the waveguide structure by adopting a pulse laser deposition process with the pulse frequency of 3.54Hz and the laser energy of 200-300 mJ2Sb2Se4Te1A phase change material film;
(3) and stripping the photoresist to obtain the 2X 2 optical waveguide switch based on the phase change material.
According to the preparation method of the 2X 2 optical waveguide switch based on the phase-change material, the thickness of the substrate is 1-100 micrometers. The length of the coupling region of the waveguide structure is 5-30 micrometers.
The technical scheme of the invention also comprises the 2X 2 optical waveguide switch based on the phase-change material, which is obtained by the preparation method.
Compared with the prior art, the invention has the beneficial effects that:
1. the invention etches and deposits Si material and phase change film GSST on SiO2On the substrate, a double-in-double-out symmetrical waveguide type optical switch is formed. When the phase change material is in an amorphous state with low emissivity and low loss and meets the optimal coupling length, the optical wave mode is coupled in the coupling area of the two waveguides, so that the output port can be selectively switched.
2. Ge adopted in the invention2Sb2Se4Te1The alloy film is prepared by a Pulsed Laser Deposition (PLD) method, and a KrF excimer laser is used for deposition under the condition of certain laser energy to obtain a uniform hundred-nanometer film which is consistent with the target material component. The deposited initial state film is in an amorphous state with low refractive index, the crystallization of the film can be triggered to be in a high-refractive-index crystalline state by annealing or applying pulse voltage, light pulse and the like, and the further amorphization reversion needs to raise the annealing temperature or utilize high pulse voltage and light pulse energy, so that the arbitrary reversion of the GSST crystalline state and the amorphous state is completed.
Drawings
Fig. 1 is a schematic structural diagram of a 2 × 2 optical waveguide switch based on a phase change material according to an embodiment of the present invention;
FIG. 2 is a top view of a phase change material based 2 × 2 optical waveguide switch structure provided by an embodiment of the present invention; in the figure, 1. an input port of one waveguide; 2. an input port of another waveguide; 3. phase change material on one waveguide; 4. phase change material on the other waveguide; 5. an output port of one waveguide; 6. an output port of the other waveguide; 7. a substrate; 8. a switching region; 9. a coupling region;
FIG. 3 is a graph of refractive index for an amorphous phase change material in a phase change material-based 2 × 2 optical waveguide switch structure according to an embodiment of the present invention;
FIG. 4 is a refractive index profile of a phase change material in a crystalline state in a phase change material-based 2 × 2 optical waveguide switch structure according to an embodiment of the present invention;
fig. 5 and fig. 6 are graphs of transmittance and extinction ratio of a phase change material-based 2 × 2 optical waveguide switch structure according to an embodiment of the present invention when a TE fundamental mode is input and output from a port;
fig. 7 is a graph of transmittance and extinction ratio of a phase change material-based 2 × 2 optical waveguide switch structure when a TM fundamental mode is input and output from a port according to an embodiment of the present invention.
Fig. 8 is a graph of transmittance and extinction ratio of a phase change material based 2 × 2 optical waveguide switch structure when a TM fundamental mode is input from a port and output from the port via double coupling according to an embodiment of the present invention.
Detailed Description
Referring to fig. 1, a schematic diagram of a 2 × 2 optical waveguide switch structure based on phase change material according to this embodiment is shown. The phase change material waveguide comprises two waveguides which are distributed in axial symmetry and comprise an input port 1, an output port 5 and covered phase change material 3 of one waveguide, and an input port 2, an output port 6 and covered phase change material 4 of the other waveguide.
Referring to fig. 2, it is a top view of the 2 × 2 optical waveguide switch structure based on phase change material provided in this embodiment. The switching region 8, shown in dashed outline as the coupling region 2, covers the phase change material. The output port of the optical signal can be changed by changing the phase of the phase change materials 3 and 4 in fig. 1 according to the input port.
In the technical scheme of the invention, the coupling length of the waveguide can be accurately calculated through a supermode coupling theory, and for TE or TM modes transmitted in the waveguide, two supermodes of TE/TM, namely an even symmetrical supermode and an odd symmetrical supermode, of the coupling system can be obtained through solving by a finite element method. The even and odd symmetrical supermodes have different propagation constants and can stably propagate in the system. Solving the two types of supermode field distributions according to a coupling mode theory to obtain the relationship between the coupling length and the effective refractive indexes of the even symmetric supermode and the odd symmetric supermode:
wherein, Lc is the coupling length,
is the propagation constant of the even supermode,
propagation constants for the odd supermode; the effective refractive indices of the even symmetric supermode and the odd symmetric supermode, respectively. Crystalline phase change materials are high index, high loss compared to amorphous. When the phase change material is changed to a crystalline state, the change of the refractive index can destroy the mode matching condition, so that the coupling area can not generate coupling, and the input optical field is directly output from the output port at the same side of the waveguide.
The waveguide material of the invention is silicon, and the substrate material of the device is silicon dioxide. The preparation method comprises the following steps:
(1) preparation of waveguide structures
In SiO2Covering a photoresist on a substrate material, and exposing a substrate by adopting a focused electron beam to obtain a device structure shape, wherein the device structure is that two waveguides are axially symmetrically distributed, two ends of each waveguide are bent, the middle of each waveguide is linear, the width of each waveguide is 100-800 nanometers, and the distance between the straight line segments of the two waveguides is 100-500 nanometers; and etching the substrate by adopting a reactive ion etching platform to obtain a waveguide structure with two input ports and two output ports with the height of 100-800 nanometers and a coupling region in the middle.
(2) Integration of phase change materials
Carrying out photoresist spin coating on the waveguide structure obtained in the step (1), carrying out electron beam exposure in a coupling area of the waveguide structure, and then adopting pulsesThe laser deposition process comprises the step of depositing Ge with the thickness of 10-300 nanometers on a coupling area of a waveguide structure by using the pulse frequency of 3.54Hz and the laser energy of 200-300 mJ2Sb2Se4Te1A phase change material film.
(3) And stripping the photoresist to obtain the 2X 2 optical waveguide switch based on the phase change material.
In this embodiment, the waveguide has a width of 385 nm, a height of 300 nm, a coupling length of 18.5 microns, and the phase change material covers the coupling waveguide, and has a width of 385 nm, a coupling length of 18.5 microns, a length of 29 microns and a width of 8.5 microns.
Referring to fig. 3, it is a refractive index curve diagram of the phase change material in the 2 × 2 optical waveguide switch structure based on the phase change material according to the present embodiment when the phase change material is in an amorphous state; curves 1 and 2 represent the refractive index and extinction coefficient, respectively. The GSST has a refractive index distribution of about 3.2 and an extinction coefficient as low as 10 in the 1550 nm range of the communication band-4Magnitude, indicating that PLD deposited GSST is a low index low loss amorphous state.
Referring to fig. 4, it is a refractive index profile of the phase change material in the 2 × 2 optical waveguide switch structure based on the phase change material according to the present embodiment when the phase change material is crystalline; curves 1 and 2 represent the refractive index and extinction coefficient, respectively. The refractive index of GSST around 1550 nm in the communication band is 5.0-5.5, the extinction coefficient is 0.0-0.5, and the refractive index and extinction coefficient of crystalline GSST are greatly changed relative to the amorphous state of initial deposition, which is also one of the most important characteristics of the film after phase transition.
Referring to fig. 5, it is a graph of transmittance and extinction ratio of the phase change material-based 2 × 2 optical waveguide switch structure provided in this embodiment when the TE fundamental mode is input from port 2 and output from port 6. Curves 1 and 2 represent the transmission and extinction ratio, respectively, of the waveguide of the output port 6. At this time, the phase change materials 3 and 4 are both in a low-loss amorphous state. Since the coupling region satisfies the matching condition, the TE fundamental mode is input from the input port 2 of one waveguide, coupled to the other compound waveguide, and output from the output port 6 of the waveguide. The insertion loss introduced in the communication band is between 0.11dB and 0.39 dB.
Referring to fig. 6, it is a graph of transmittance and extinction ratio of the phase change material-based 2 × 2 optical waveguide switch structure provided in this embodiment when the TE fundamental mode is input from port 2 and output from port 5. Curves 1 and 2 represent the transmission and extinction ratio, respectively, of the waveguide of the output port 5. At this time, the phase change material 3 is in a low-loss amorphous state, and the phase change material 4 is in a crystalline state. The high index phase change material creates a mode mismatch in the coupling region and the TE fundamental mode is output directly from port 5 of the waveguide. The insertion loss introduced in the communication band is between 0.64dB and 0.88 dB.
Referring to fig. 7, it is a graph of transmittance and extinction ratio of the 2 × 2 optical waveguide switch structure based on phase change material provided in this embodiment when the TM fundamental mode is input from port 2 and output from port 5. Curves 1 and 2 represent the transmission and extinction ratio, respectively, of the waveguide of the output port 5. Both phase change materials 3 and 4 are now in a low-loss amorphous state. Since the coupling region satisfies the matching condition, the TE fundamental mode is coupled to another composite waveguide and is coupled back to the original composite waveguide again and is output from the port 5 of the waveguide. The insertion loss introduced in the communication band is between 0.12dB and 0.7 dB.
Referring to fig. 8, it is a graph of the transmission and extinction ratio of the phase change material-based 2 × 2 optical waveguide switch structure provided in this embodiment when the TM fundamental mode is input from port 2 and output from port 5 through two couplings. Curves 1 and 2 are the transmission and extinction ratios, respectively, of the waveguide of the output port 5. At this time, the phase change material 3 is in a low-loss amorphous state, and the phase change material 4 is in a crystalline state. The high index phase change material causes mode mismatch in the coupling region and the TE fundamental mode is directly output from port 5 without coupling. The insertion loss introduced in the communication band is between 1.55dB and 2.1 dB.
Claims (4)
1. A preparation method of a 2 x 2 optical waveguide switch based on a phase change material is characterized by comprising the following steps:
(1) preparation of waveguide structures
In SiO2Covering a substrate material with photoresist, and exposing the substrate with focused electron beam to obtain a device structure shape with two waveguides axially symmetrically dividedThe two ends of each waveguide are bent, the middle of each waveguide is linear, the width of each waveguide is 100-800 nanometers, and the distance between the straight line sections of the two waveguides is 100-500 nanometers; etching the substrate by adopting a reactive ion etching platform to obtain a waveguide structure with two input ports and two output ports with the height of 100-800 nanometers and a coupling region in the middle;
(2) integration of phase change materials
Carrying out photoresist spin coating on the waveguide structure obtained in the step (1), carrying out electron beam exposure on a coupling area of the waveguide structure, and then depositing Ge with the thickness of 10-300 nanometers on the coupling area of the waveguide structure by adopting a pulse laser deposition process with the pulse frequency of 3.54Hz and the laser energy of 200-300 mJ2Sb2Se4Te1A phase change material film;
(3) and stripping the photoresist to obtain the 2X 2 optical waveguide switch based on the phase change material.
2. The method of claim 1 for fabricating a phase change material based 2 x 2 optical waveguide switch, wherein: the thickness of the substrate is 1 to 100 μm.
3. The method of claim 1 for fabricating a phase change material based 2 x 2 optical waveguide switch, wherein: the length of the coupling region of the waveguide structure is 5-30 micrometers.
4. A 2 x 2 optical waveguide switch based on phase change material obtained by the method of claim 1.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114815330A (en) * | 2022-06-30 | 2022-07-29 | 中山大学 | MZI type optical switch capable of accurately regulating and controlling phase of interference arm and preparation method thereof |
| 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 |
| CN116224498A (en) * | 2023-05-09 | 2023-06-06 | 之江实验室 | On-chip switch, forming method thereof and optical communication element |
| CN116300242A (en) * | 2023-02-28 | 2023-06-23 | 中国人民解放军国防科技大学 | Micro-ring optical waveguide switch based on low-loss phase change material and preparation method thereof |
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2021
- 2021-12-21 CN CN202111573963.7A patent/CN114326164A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114815330A (en) * | 2022-06-30 | 2022-07-29 | 中山大学 | MZI type optical switch capable of accurately regulating and controlling phase of interference arm and preparation method thereof |
| 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 |
| CN116300242A (en) * | 2023-02-28 | 2023-06-23 | 中国人民解放军国防科技大学 | Micro-ring optical waveguide switch based on low-loss phase change material and preparation method thereof |
| CN116300242B (en) * | 2023-02-28 | 2024-02-06 | 中国人民解放军国防科技大学 | Micro-ring optical waveguide switch based on low-loss phase change material and preparation method thereof |
| CN116224498A (en) * | 2023-05-09 | 2023-06-06 | 之江实验室 | On-chip switch, forming method thereof and optical communication element |
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