Non-volatile reconfigurable on-chip integrated super lens based on phase change material
By using phase change materials to build subwavelength units in an on-chip integrated superlens, and using electrode heating to regulate the refractive index of the phase change material, the problem of superlens not having nonvolatile and zero static power consumption in the prior art is solved, and the dynamic focus of the beam and the potential of integrated photon system are realized.
Patent Information
- Application Number
- CN202510231271.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-28
- Publication Date
- 2025-05-27
AI Technical Summary
Existing on-chip integrated ultralenses do not have nonvolatile and zero static power consumption, and the heating solution is complex, which is not conducive to the integration of photonic devices.
A nonvolatile reconfigurable on-chip integrated superlens design based on phase change materials is adopted. By etching grooves on the waveguide and growing the phase change material, sub-wavelength units are formed, and the phase change material is heated by electrodes to make it phase change, thereby regulating the focus position of the light beam.
It realizes the non-volatile reconfigurable function of on-chip ultralens, has small size and zero static power consumption characteristics, is simple in electronic control solution, is compatible with CMOS processes, and has the potential for large-scale applications.
Smart Images
Figure CN120044710A_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of on-chip integrated metalenses, and more specifically, relates to a non-volatile reconfigurable on-chip integrated metalens based on phase change materials. Background Art
[0002] An on-chip integrated metalens is an optical element based on metalens technology that integrates a metasurface structure with a chip to achieve functions such as beam focusing and zooming. Its design typically includes a metasurface structure (such as a slot waveguide array) and an electrically controlled heater structure. By precisely controlling the local effective refractive index of the waveguide through the electrically controlled heater, beam focusing and zooming can be achieved.
[0003] Most of the materials in existing metasurface structures are metal materials (such as gold, silver, and aluminum) or dielectric materials (such as titanium dioxide and silicon nitride). The tunable mechanisms are mostly volatile electro-optic effects or thermo-optic effects, which do not have non-volatility and zero static power consumption. At the same time, the heating scheme is complex, which is not conducive to the integration of photonic devices. Summary of the Invention
[0004] Aiming at the defects of the existing technology, the purpose of this application is to provide a non-volatile reconfigurable on-chip integrated metalens based on phase change materials, aiming to solve the problems that existing on-chip integrated metalenses do not have non-volatility and zero static power consumption, and at the same time, the heating scheme is complex, which is not conducive to the integration of photonic devices.
[0005] This application relates to a non-volatile reconfigurable on-chip integrated metalens based on phase change materials, including: A waveguide etched with a plurality of grooves, the plurality of grooves are horizontally symmetrically and uniformly distributed about the horizontal axis of symmetry of the waveguide, the widths of the grooves are equal, and the lengths gradually increase from the horizontal axis of symmetry to both sides; The same phase change material is grown in each groove, and the phase change material in a single groove and the adjacent waveguide material together form a sub-wavelength unit; An electrode disposed on the waveguide, covering all sub-wavelength units and extending earpieces in the vertical direction, and the earpieces are used to connect to a control voltage pulse; A covering layer disposed on the electrode, and the covering layer is used to prevent the electrode from oxidizing and conduct heat at the same time.
[0006] In some embodiments, the width of the sub-wavelength unit is jointly determined by the operating wavelength of the on-chip integrated metalens and the refractive index of the waveguide.
[0007] In some embodiments, the number of sub-wavelength units is jointly determined by the diameter of the on-chip integrated metalens and the width of the sub-wavelength unit.
[0008] In some embodiments, the sub-wavelength unit has a transmittance of more than 0.95 and can achieve phase shift.
[0009] In some embodiments, after fixing the width of the phase change material, the ideal phase of the sub-wavelength unit at different lengths with a fixed width of the phase change material is obtained through the lens phase formula, and linear interpolation is performed on the ideal phase and the simulated phase to obtain the length distribution of the sub-wavelength unit array.
[0010] In some embodiments, the phase change material and the waveguide have the same thickness.
[0011] In some embodiments, the phase change material is a low-loss phase change material, and its loss is nearly zero in the C and L bands of the optical communication band.
[0012] In some embodiments, the material of the cladding layer is silicon oxide or aluminum oxide.
[0013] In some embodiments, the electrode is a transparent conductive oxide film.
[0014] In some embodiments, it further includes: a substrate located at the bottom layer, and a lower cladding layer stacked between the substrate and the waveguide; the material of the substrate is silicon, and the material of the lower cladding layer is silicon oxide.
[0015] Generally speaking, compared with the prior art through the above technical solutions conceived by the present application, the following beneficial effects are obtained: The present application proposes a non-volatile reconfigurable on-chip integrated superlens based on a phase change material. The sub-wavelength unit is a waveguide-phase change material-waveguide sandwich structure, and the electrode for externally connecting a control voltage pulse covers the entire sub-wavelength unit. The phase change material is heated to cause a phase change, and then the refractive index of the phase change material changes, and the phase of light passing through the sub-wavelength unit changes, thereby changing the focusing position of the light beam and realizing the dynamic focusing of the light beam. It can endow the on-chip superlens with non-volatile reconfigurable functions, and has the characteristics of small size and zero static power consumption; at the same time, only one heater is required, and the electronic control scheme is simple; in addition, the device is compatible with the existing CMOS process, has the potential for large-scale applications, and can be used in reconfigurable integrated photonics systems. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 is a top view of a non-volatile reconfigurable on-chip integrated superlens based on a phase change material provided by an embodiment of the present application.
[0017] Figure 2 is a cross-sectional schematic diagram of a non-volatile reconfigurable on-chip integrated superlens based on a phase change material provided by an embodiment of the present application.
[0018] Figure 3 is the relationship between the transmittance of the sub-wavelength unit and the width and length of the phase change material provided by an embodiment of the present application.
[0019] Figure 4 It shows the relationship between the phase of the sub-wavelength unit provided by the embodiment of the present application and the width and length of the phase change material.
[0020] Figure 5 It shows the relationship between the transmittance and phase of the sub-wavelength unit provided by the embodiment of the present application when the width of the phase change material is 200 nm and the length changes.
[0021] Figure 6 It shows the electric field distribution diagram of the on-chip superlens provided by the embodiment of the present application when the phase change material is in the amorphous state.
[0022] Figure 7 It shows the electric field distribution diagram of the on-chip superlens provided by the embodiment of the present application when the phase change material is in the crystalline state.
[0023] Figure 8 It shows the relationship between the temperature of the amorphous phase change material and time provided by the embodiment of the present application.
[0024] Figure 9 It shows the relationship between the temperature of the crystalline phase change material and time provided by the embodiment of the present application.
[0025] Figure 10 It shows the flow chart of the preparation method of a non-volatile reconfigurable on-chip integrated superlens based on phase change material provided by the embodiment of the present application.
[0026] In all the drawings, the same reference numerals are used to represent the same elements or structures, where: 1 - lower cladding, 2 - waveguide, 3 - phase change material, 4 - electrode, 5 - covering layer, 6 - substrate, 7 - tab. Detailed implementation manners
[0027] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.
[0028] The embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application.
[0029] As Figure 1 and Figure 2 shown, the present application provides a non-volatile reconfigurable on-chip integrated superlens based on phase change material, including: A waveguide 2 etched with a plurality of grooves, the plurality of grooves are evenly distributed horizontally symmetrically about the horizontal axis of symmetry of the waveguide 2, the widths of the grooves are equal, and the lengths gradually increase from the horizontal axis of symmetry to both sides; The same phase change material 3 is grown in each groove, and the phase change material in a single groove and the adjacent waveguide material together form a sub-wavelength unit; The electrode 4 disposed on the waveguide covers all sub-wavelength units and extends the tab 7 in the vertical direction, and the tab is used to access the regulated voltage pulse; The covering layer 5 disposed on the electrode, and the covering layer is used to prevent the oxidation of the electrode and conduct heat at the same time.
[0030] In this application, the on-chip integrated superlens is constructed on a silicon-on-insulator platform SOI. The superlens structure is composed of an array of sub-wavelength units, which is used to realize reconfigurable non-volatile on-chip beam focusing; the heater structure is composed of the electrode 4 and the covering layer 5, which is used to heat the phase change material to cause the phase change material to undergo a phase change, and then regulate the effective refractive index of the sub-wavelength unit to realize the dynamic focusing of the beam.
[0031] Preferably, the phase change material 3 is a low-loss phase change material, and its loss is almost 0 in the C and L bands of the optical communication band, such as antimony sulfide.
[0032] Preferably, the material of the covering layer 5 is silicon oxide or aluminum oxide, and the thickness is 100-200 nm.
[0033] Preferably, the electrode 4 is a transparent conductive oxide film, such as ITO or AZO, and the thickness is 250-350 nm.
[0034] The number and arrangement of the sub-wavelength units are determined by the diameter, focal length, and lens phase of the on-chip superlens.
[0035] Preferably, the width of the sub-wavelength unit is jointly determined by the working wavelength of the on-chip integrated superlens and the waveguide refractive index.
[0036] Preferably, the number of the sub-wavelength units is jointly determined by the diameter of the on-chip integrated superlens and the width of the sub-wavelength unit.
[0037] Preferably, the sub-wavelength unit has a transmittance of more than 0.95 and can achieve phase shift.
[0038] Preferably, after fixing the width of the phase change material, the ideal phase of the sub-wavelength unit at different lengths under the fixed width of the phase change material is obtained through the lens phase formula, and linear interpolation is performed on the ideal phase and the simulated phase to obtain the length distribution of the sub-wavelength unit array.
[0039] The phase formula of the on-chip superlens adopts the phase formula required by a convex lens as:
[0040] Among them, is the working wavelength of the device, is the effective refractive index of the waveguide of the device, is the lens focal length of the device, is the length distance of the device along the x-axis from the center to the edge.
[0041] Preferably, the on-chip superlens further includes: a substrate 6 located at the bottom layer, and a lower cladding 1 stacked between the substrate and the waveguide; the material of the substrate is silicon, and the material of the lower cladding is silicon dioxide.
[0042] Embodiment In this embodiment, the diameter of the on-chip superlens is set to 10 um, the focal length is set to 30 um, the working wavelength is selected as 1550 nm commonly used in optical communication, the material of the waveguide is silicon, and the refractive index is about 3.45. Therefore, the width of the sub-wavelength unit is 500 nm, and the number of sub-wavelength units is 19.
[0043] The finite-difference time-domain algorithm is used to solve the electromagnetic field of the sub-wavelength unit at the input optical wavelength of 1550 nm. The width range of the phase change material is set to 0 - 500 nm, and the length range is set to 0 - 4.5 um, and the corresponding transmittance and phase of the sub-wavelength unit are obtained. As Figure 3 and Figure 4 shown, where width is the width of the phase change material, length is the length of the phase change material, transmission is the transmittance of the sub-wavelength unit, and Phase is the phase of the sub-wavelength unit, with the unit of rad.
[0044] In order to make the sub-wavelength unit have a transmittance of more than 0.95, phase shift and facilitate subsequent process processing, the width of the phase change material is set to 200 nm. As Figure 5 shown, when the width of the phase change material is set to 200 nm and the length range is 0 - 4.5 um, the transmittance of the sub-wavelength unit reaches more than 0.95, and at the same time, the phase shift can achieve the range of. The ideal phase of the sub-wavelength unit with a phase change material width of 200 nm and a length range of 0 - 4.5 um is obtained through the lens phase formula. Linear interpolation is performed on the ideal phase and the simulated phase to obtain the length distribution of the sub-wavelength unit array.
[0045] In this embodiment, after obtaining the length distribution of the sub-wavelength unit array, the finite-difference time-domain algorithm is used to perform electromagnetic simulation on the on-chip superlens, and the electromagnetic field distribution diagrams of the on-chip superlens when the phase change material is in the amorphous state and the crystalline state are obtained, as shown in Figure 6 and Figure 7 shown respectively, where x represents the longitudinal position and y represents the transverse position. represents the electric field strength. The phase change material of the sub-wavelength unit can be regulated by applying voltage pulses to cause a phase change. The phase change states include two types: amorphous state and crystalline state. When the phase change material undergoes a phase change, the refractive index of the phase change material changes, the phase of the light passing through the sub-wavelength unit changes, and thus the focusing position of the light beam is changed, realizing the dynamic focusing of the light beam. When the phase change material is in the amorphous state, the on-chip superlens focuses at 30um, as Figure 6 shown; when the phase change material is in the crystalline state, the on-chip superlens focuses at 25um, as Figure 7 shown.
[0046] In this embodiment, the finite element simulation is used to study the temperature influence of the ITO electrode on the phase change material, as shown in Figure 8 and Figure 9 respectively. First, a low-voltage long electrical pulse of 2V and 1us is used to heat the amorphous antimony sulfide phase change material. The temperature of the antimony sulfide material can reach 300 within 1us, realizing the transition from the amorphous state to the crystalline state, as shown in Figure 8 ; A high-voltage short electrical pulse of 4V and 200ns is used to heat the crystalline antimony sulfide phase change material. The temperature of the antimony sulfide material can reach 642 within 200ns, realizing the transition from the crystalline state to the amorphous state, as shown in Figure 9 shown.
[0047] As shown in Figure 10 , this application also provides a preparation method of a non-volatile reconfigurable on-chip integrated superlens based on a phase change material. The specific steps are as follows: 1) Use electron beam lithography technology and inductively coupled plasma etching technology to form a waveguide; 2) Use electron beam lithography technology and inductively coupled plasma etching technology to form slits in the waveguide; 3) Use thin film deposition technology to grow 220nm of antimony sulfide material at the slits to form a sub-wavelength array; 4) Use thin film deposition technology to grow 300nm of ITO on the surface of the phase change material as an electrode; 5) Use plasma chemical deposition method to grow 200nm of silicon dioxide on the electrode to form a covering layer at a temperature of 100°C; 6) Use inductively coupled plasma etching technology to etch the covering layer to expose the electrode, obtaining an on-chip integrated superlens device; 7) Connect an external voltage source to the electrode and heat it to cause the phase change material to undergo a phase change.
[0048] It should be understood that expressions such as "including" and "may include" that can be used in this application indicate the existence of the disclosed functions, operations, or components, and do not limit one or more additional functions, operations, and components. In this application, terms such as "including" and / or "having" can be interpreted as indicating a specific characteristic, number, operation, component, component, or a combination thereof, but cannot be interpreted as excluding the existence or possibility of addition of one or more other characteristics, numbers, operations, components, components, or a combination thereof.
[0049] In addition, in this application, the expression "and / or" includes any and all combinations of the associated listed words. For example, the expression "A and / or B" can include A, can include B, or can include both A and B.
[0050] In the description of the embodiments of this application, it should be noted that unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. Among them, "fixed connection" means that the two are connected and the relative positional relationship after connection remains unchanged. "Rotational connection" means that the two are connected and can rotate relative to each other after connection. "Sliding connection" means that the two are connected and can slide relative to each other after connection. The orientation terms mentioned in the embodiments of this application, such as "top", "bottom", "inside", "outside", "left", "right", etc., are only with reference to the direction of the accompanying drawings. Therefore, the orientation terms used are for better and clearer description and understanding of the embodiments of this application, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the embodiments of this application.
[0051] In addition, in the embodiments of this application, mathematical concepts such as symmetry, equality, parallelism, and perpendicularity are mentioned. These limitations are all in view of the current technological level, rather than absolute strict definitions in the mathematical sense. A small deviation is allowed, and being approximately symmetric, approximately equal, approximately parallel, approximately perpendicular, etc. are all acceptable. For example, A is parallel to B means that A is parallel to B or approximately parallel to B, and the included angle between A and B can be between 0 degrees and 10 degrees. A is perpendicular to B means that A is perpendicular to B or approximately perpendicular to B, and the included angle between A and B can be between 80 degrees and 100 degrees.
[0052] The above is only the specific implementation manner of this application, but the protection scope of this application is not limited thereto. Any person skilled in the art within the technical scope disclosed in this application can easily think of changes or substitutions, which should all be covered by the protection scope of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claims.
Claims
1. A non-volatile reconfigurable on-chip integrated superlens based on phase change material, characterized in that: include: A waveguide having a plurality of grooves etched therein, wherein the plurality of grooves are uniformly distributed laterally about a horizontal symmetry axis of the waveguide, the width of each groove is equal, and the length gradually increases from both sides of the horizontal symmetry axis; The same phase change material is grown in each groove, and the phase change material in a single groove and the adjacent waveguide material together constitute a sub-wavelength unit; The electrode is arranged on the waveguide, covers all sub-wavelength units and extends a pole ear in a vertical direction, and the pole ear is used to receive a regulating voltage pulse; The covering layer is arranged on the electrode, and is used to prevent the electrode from oxidation and to conduct heat at the same time.
2. The on-chip integrated superlens according to claim 1, characterized in that The width of the sub-wavelength unit is determined by the working wavelength of the on-chip integrated metalens and the refractive index of the waveguide.
3. The on-chip integrated superlens according to claim 2, characterized in that The number of the sub-wavelength units is determined by the diameter of the on-chip integrated metalens and the width of the sub-wavelength unit.
4. The on-chip integrated superlens according to claim 1, characterized in that The sub-wavelength unit has a transmittance of more than 0.95 and can achieve Phase shift.
5. The on-chip integrated superlens according to claim 4, characterized in that After fixing the width of the phase change material, the ideal phase of the subwavelength unit at different lengths under the fixed width of the phase change material is obtained through the lens phase formula. The ideal phase and the simulated phase are linearly interpolated to obtain the length distribution of the subwavelength unit array.
6. The on-chip integrated superlens according to claim 1, characterized in that The phase change material and the waveguide have the same thickness.
7. The on-chip integrated superlens according to claim 1, characterized in that The phase change material is a low-loss phase change material, and its loss is almost zero in the C and L bands of the optical communication band.
8. The on-chip integrated superlens according to claim 1, characterized in that: The material of the cover layer is silicon oxide or aluminum oxide.
9. The on-chip integrated superlens according to claim 1, characterized in that: The electrode is a transparent conductive oxide film.
10. The on-chip integrated superlens according to any one of claims 1 to 9, characterized in that: Also includes: A substrate at the bottom layer, and a lower cladding layer stacked between the substrate and the waveguide; The material of the substrate is silicon, and the material of the lower cladding layer is silicon oxide.