Electric control polariton switching device based on positive and negative phase velocity waveguide hybrid coupling and preparation method thereof

Abstract

The invention discloses an electrically controlled polariton switching device based on hybrid coupling of positive and negative phase velocity waveguides and a preparation method, and relates to the technical field of optical switching devices, the electrically controlled polariton switching device comprises an antenna, a forward phase velocity waveguide, a reverse phase velocity waveguide, a substrate, a signal detection device and a grid voltage structure; the antenna, the forward phase velocity waveguide and the signal detection device are all connected with the reverse phase velocity waveguide, the reverse phase velocity waveguide is connected with the substrate, and the grid voltage structure is connected with the substrate and the forward phase velocity waveguide. According to the invention, polariton hybrid coupling with opposite phase velocities is utilized to induce the system to spontaneously and symmetrically break so as to generate a polariton forbidden band. The position of a forbidden band is regulated and controlled by adjusting the magnitude of the electrical grid voltage, and the polarization polariton is dynamically converted from an on state to an off state. According to the method, electrically-controlled polariton switch regulation and control in a nanoscale plane can be achieved, the large switch ratio and the small modulation voltage are achieved, the device structure is simple and easy to implement, the application range is wide, and the cost is low.

Description

Technical Field

[0001] The present invention relates to the technical field of optical switch devices, and more specifically to an electrically controlled polariton switch device based on positive and negative phase velocity waveguide hybrid coupling and a preparation method thereof. Background Art

[0002] In photonics and optoelectronics, the amplitude, phase, polarization and other basic properties of light can be used to effectively control the optical path. Optical switching devices are the most basic type of optical control devices, which are widely used in photonic circuits, analog optics, logic operations and optical sensors. Traditional optical switching devices include electroabsorption and phase interference schemes, which use electron transitions and phase interference of light to control the amplitude of light in optical waveguides, thereby achieving on-off control of the optical path. However, due to the existence of optical diffraction, traditional optical switching devices usually require a size of hundreds of microns to achieve on-off control of optical path signals, which limits the integration of optical devices. Therefore, the development of nanoscale optical switching devices with high efficiency, low optical loss and environmental stability has gradually become inevitable.

[0003] Compared with traditional bulk materials, two-dimensional van der Waals layered materials can support surface wave transmission of polaritons due to their atomic layer thickness, breaking through the traditional diffraction limit, greatly compressing the device size, and increasing the integration of the device, making it show unique advantages in light regulation and attracting widespread attention from researchers. Conventional polaritons have a positive phase velocity, and its direction is consistent with the direction of energy transmission. For some special polaritons, such as molybdenum oxide phonon polaritons, since their in-plane dielectric function is positive and out-of-plane is negative, the phase velocity direction of their polaritons is opposite to the direction of energy transmission. This unique physical phenomenon brings a new dimension to the regulation of polaritons. When such polaritons with opposite phase velocities are hybridized and coupled to form a waveguide, a symmetry breaking effect will occur spontaneously, resulting in an optical bandgap. By regulating the electrical gate voltage, the coupling of polaritons can be dynamically regulated, the position of the switch-off can be controlled, and the continuous change of polaritons from on to off can be achieved.

[0004] Therefore, how to use the principle of positive and negative phase velocity waveguide hybrid coupling to obtain a new waveguide switch device, realize sub-nanometer scale optical switch control, and reduce processing and preparation losses is an urgent problem that technicians in this field need to solve. Summary of the invention

[0005] In view of this, the present invention provides an electrically controlled polariton switch device based on positive and negative phase velocity waveguide hybrid coupling and a preparation method thereof, and utilizes positive and negative phase velocity waveguide hybrid coupling to obtain a novel waveguide switch device, realizes sub-nanometer scale optical switch control, and reduces the geometric design size of the device through a two-dimensional stacking design, thereby reducing the processing and preparation loss. In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions:

[0006] An electrically controlled polariton switch device based on hybrid coupling of positive and negative phase velocity waveguides comprises: an antenna, a forward phase velocity waveguide, a reverse phase velocity waveguide, a substrate, a signal detection device and a gate voltage structure; the antenna, the forward phase velocity waveguide and the signal detection device are all connected to the reverse phase velocity waveguide, the reverse phase velocity waveguide is connected to the substrate, and the gate voltage structure is respectively connected to the substrate and the forward phase velocity waveguide.

[0007] Optionally, the signal detection device is a scattering scanning near-field optical microscope tip, which is used for signal detection.

[0008] Optionally, the method further includes using an incident electromagnetic wave to illuminate the antenna to excite polaritons in the waveguide at the boundary.

[0009] Optionally, the incident electromagnetic wave is concentrated in the infrared region, with a wavelength range of 970-8000cm -1 .

[0010] Optionally, the polaritons in the waveguide are transmission-type polaritons, and specifically may be phonon polaritons, plasmons, or exciton polaritons.

[0011] Optionally, the gate voltage structure is used to adjust the hybrid coupling coefficient of the positive and negative phase velocity waveguides by changing the carrier concentration of the forward phase velocity waveguide, thereby controlling the transmission on and off of the transmission-type polariton waveguide.

[0012] Optionally, a method for preparing an electrically controlled polariton switching device based on positive and negative phase velocity waveguide hybrid coupling includes: utilizing polariton hybrid coupling with opposite phase velocities to induce spontaneous symmetry breaking of the system to generate a polariton bandgap, and dynamically switching the polariton from an on state to an off state by adjusting the electrical gate voltage of the gate voltage structure to control the bandgap position.

[0013] Optionally, the preparation method comprises:

[0014] S1: Preparation of waveguide structure with reverse phase velocity;

[0015] S2: Select the shape and size of the antenna and make the antenna;

[0016] S3: Selecting a substrate material and preparing the substrate;

[0017] S4: preparing a waveguide structure with a positive phase velocity, and transferring the structure to a waveguide structure with a reverse phase velocity to construct a gate voltage structure;

[0018] S5: placing the antenna on the switch device, coupling the incident far-field light to the optical switch device, and exciting the transmission-type polaritons mode;

[0019] S6: Change the gate voltage to control the continuous change of the device from the on state to the off state.

[0020] It can be seen from the above technical solutions that, compared with the prior art, the present invention discloses an electrically controlled polariton switch device based on positive and negative phase velocity waveguide hybrid coupling and a preparation method thereof, which has the following beneficial effects:

[0021] The present invention proposes an electrically controlled polariton switch device based on hybrid coupling of positive and negative phase velocity waveguides, comprising: an antenna, a forward phase velocity waveguide, a reverse phase velocity waveguide, a substrate, a signal detection device and a gate voltage structure; the antenna, the forward phase velocity waveguide and the signal detection device are all connected to the reverse phase velocity waveguide, the reverse phase velocity waveguide is connected to the substrate, and the gate voltage structure is respectively connected to the substrate and the forward phase velocity waveguide. The present invention realizes the on-off control of polariton waveguide transmission by changing the gate voltage. The present invention realizes (1) polaritons break through the diffraction limit, compress the propagation wavelength, and realize the device structure of hundreds of nanometers; (2) by changing the gate voltage, the on-off control of the polariton waveguide can be dynamically realized; (3) the switch device ensures a smaller control gate voltage <8V and a larger switch ratio >25; (4) the device structure is realized by stacking natural materials, avoiding the loss problem caused by defects introduced by processing; (5) the dynamic control of the polariton switch device has a wide range of applications, and the method is simple and easy to implement with low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0023] Figure 1 A schematic diagram of an electrically controlled polariton switching device based on positive and negative phase velocity waveguide hybrid coupling provided by the present invention.

[0024] Figure 2 A flow chart of a method for preparing an electrically controlled polariton switching device based on positive and negative phase velocity waveguide hybrid coupling provided by the present invention.

[0025] Figure 3The present invention provides a dispersion diagram of hybrid polaritons in the overlapping region of positive and negative phase velocity waveguides under different gate voltages.

[0026] FIG. 4( a ) is a COMSOL simulation cross-sectional view of polariton waveguide transmission provided by the present invention at a Fermi level of 0 eV-0.3 eV.

[0027] FIG. 4( b ) is an intensity distribution diagram of polariton transmittance at different Fermi energies provided by the present invention.

[0028] FIG4( c ) is a diagram showing the switching ratio of the electrically controlled polariton switching device provided by the present invention at a Fermi energy of 0 eV-0.6 eV.

[0029] FIG5( a ) is a structural light field diagram of the electrically controlled polariton switching device provided by the present invention.

[0030] FIG5( b ) is a diagram showing the near-field intensity of the polariton waveguide under the regulated electrical gate voltage provided by the present invention.

[0031] FIG6( a ) is an experimentally extracted intensity diagram of the near-field signal of the electrically controlled polariton switching device provided by the present invention as the Fermi energy changes.

[0032] FIG6( b ) is an experimental distribution diagram of the near-field signal transmittance and switching ratio of the electrically regulated polariton switching device provided by the present invention as the Fermi energy varies.

[0033] Among them, 101 is an antenna, 102 is a reverse phase velocity waveguide, 103 is a signal detection device, 104 is a forward phase velocity waveguide, 105 is a gate voltage structure, and 106 is a substrate. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] The embodiment of the present invention discloses an electrically controlled polariton switch device based on hybrid coupling of positive and negative phase velocity waveguides, comprising: an antenna 101, a forward phase velocity waveguide 104, a reverse phase velocity waveguide 102, a substrate 106, a signal detection device 103 and a gate voltage structure 105; the antenna 101, the forward phase velocity waveguide 104 and the signal detection device 103 are all connected to the reverse phase velocity waveguide 102, the reverse phase velocity waveguide 102 is connected to the substrate 106, and the gate voltage structure 105 is respectively connected to the substrate 106 and the forward phase velocity waveguide 104.

[0036] Furthermore, the signal detection device 103 is a scattering type scanning near-field optical microscope tip, which is used for signal detection.

[0037] Furthermore, the antenna 101 may be a metal antenna, and the size of the metal antenna may be variable.

[0038] Furthermore, the method also includes using incident electromagnetic waves to illuminate the antenna 101 to excite polaritons in the waveguide at the boundary.

[0039] Furthermore, the incident electromagnetic wave is concentrated in the infrared region, with a wavelength range of 970-8000cm -1 .

[0040] Furthermore, the polaritons in the waveguide are transmission-type polaritons, and specifically may be phonon polaritons, plasmons, or exciton polaritons.

[0041] Furthermore, the gate voltage structure 105 is used to adjust the positive and negative phase velocity waveguide hybrid coupling coefficients by changing the carrier concentration of the forward phase velocity waveguide 104, thereby controlling the transmission on and off of the transmission-type polariton waveguide.

[0042] Furthermore, the preparation method comprises:

[0043] S1: Preparation of waveguide structure with reverse phase velocity;

[0044] S2: Select the shape and size of the antenna 101 and manufacture the antenna 101;

[0045] S3: Selecting a substrate 106 material and preparing the substrate 106;

[0046] S4: preparing a waveguide 104 with a forward phase velocity, and transferring the structure to the waveguide 102 with a reverse phase velocity, to construct a gate voltage structure 105;

[0047] S5: placing the antenna 101 on the switch device, coupling the incident far-field light to the optical switch device, and exciting the transmission-type polariton mode;

[0048] S6: Change the gate voltage to control the continuous change of the device from the on state to the off state.

[0049] The present invention utilizes hybrid coupling of polaritons with opposite phase velocities to induce spontaneous symmetry breaking of the system and generate a polariton bandgap. By adjusting the size of the electrical gate voltage and regulating the position of the bandgap, the polaritons are dynamically transformed from the on state to the off state. The method can realize the electrically controlled polaritons switching control in the nanoscale plane, with a switching ratio of >25 and a modulation voltage of less than <8V. The method is different from the traditional electroabsorption modulator and phase modulator, and the device structure is simple and easy, with a wide range of applications and low cost.

[0050] In a specific embodiment, Figure 3 As shown, this embodiment is based on the electrically controlled polariton switch device realized by the hybrid coupling of positive and negative phase velocity waveguides. By utilizing the hybrid coupling of polaritons with opposite phase velocities, the spontaneous symmetry breaking of the system is induced to generate a polariton bandgap. By adjusting the size of the electrical gate voltage and regulating the position of the bandgap, the transition of the polariton from the on state to the off state is dynamically realized.

[0051] In a specific embodiment, the cross-section of the forward phase velocity waveguide 104 can be square, rod-shaped, ellipsoidal or other structures; its geometric size is 100nm-100um, and its thickness is 3nm-600nm; the material of the forward phase velocity waveguide 104 includes graphene, black phosphorus, silver, iron, copper, aluminum, graphite, and transition metal sulfide.

[0052] In a specific embodiment, the cross-section of the reverse phase velocity waveguide 102 can be square, rod-shaped, ellipsoidal or other structures; its geometric dimensions are 100nm-100um, and its thickness is 3nm-600nm; the material of the reverse phase velocity waveguide 102 includes molybdenum oxide, boron nitride, silicon carbide, gallium oxide, and chromium tungstate.

[0053] In a specific embodiment, the antenna 101 is a metal antenna, and the shape of the metal antenna can be square, rod-shaped, ellipsoidal or other structures; its geometric size is 10nm-20um, and the thickness is 20nm-1um. The material of the antenna 101 is selected from silver, iron, copper, aluminum, platinum, gold, and steel.

[0054] In a specific embodiment, the material of the substrate 106 includes an inorganic dielectric material and an organic polymer material. The inorganic dielectric material is selected from silicon dioxide, silicon, quartz, sapphire, germanium, aluminum oxide, boron nitride, calcium fluoride, magnesium fluoride, gallium arsenide, gallium nitride, gold, and silver; the organic polymer material substrate is selected from PET, PMMA, PDMS, and plastic.

[0055] In a specific embodiment, a method for preparing an electrically controlled polariton switch device based on positive and negative phase velocity waveguide hybrid coupling includes the following steps:

[0056] Step 1): preparing a waveguide structure with a reverse phase velocity;

[0057] Step 2): Select the shape and size of the antenna 101 and make a metal antenna;

[0058] Step 3): Selecting a substrate 106 material and preparing the substrate 106;

[0059] Step 4): preparing a waveguide structure with a forward phase velocity, and transferring the structure onto a waveguide structure with a reverse phase velocity, thereby constructing a gate voltage structure 105;

[0060] Step 5): Transfer the metal antenna to the entire device, couple the incident far-field light to the optical switch device, and excite the transmission-type polaritons mode;

[0061] Step 6): Change the gate voltage to achieve a continuous change of the device from the on state to the off state.

[0062] Furthermore, the method for exciting polaritons is: using incident light to illuminate the antenna 101 to excite polaritons in the waveguide at the boundary.

[0063] In a specific embodiment, a schematic diagram of an electrically controlled polariton switch device based on positive and negative phase velocity waveguide hybrid coupling is shown in FIG. Figure 1 As shown, transmission-type polaritons are excited by antenna 101 and propagate on waveguide 102 with reverse phase velocity. The tip of a scattering-type scanning near-field optical microscope is used as a signal detection device 103. The device is placed on a substrate 106. The polariton coupling coefficient of waveguide 104 with forward phase velocity is changed by means of a gate voltage structure 105 to control the transmission on and off of the polariton waveguide.

[0064] In a specific embodiment, a method for preparing an electrically controlled polariton switch device based on positive and negative phase velocity waveguide hybrid coupling is shown in the flowchart. Figure 2 As shown, the following steps are included:

[0065] Step 201: Prepare a waveguide structure with a reverse phase velocity.

[0066] The cross section of the waveguide structure with reverse phase velocity can be square, rod-shaped, ellipsoidal or other structures; its geometric size is 100nm-100um, and its thickness is 3nm-600nm. The material of the waveguide structure with reverse phase velocity includes molybdenum oxide, boron nitride, silicon carbide, gallium oxide, and chromium tungstate.

[0067] Step 202: Select the shape and size of the antenna 101 and make a metal antenna.

[0068] The metal antenna may be in the shape of a square, a grid or other structures; its geometric size is 10nm-30um, and its thickness is 20nm-5um. The material of the cover metal antenna may be selected from iron, aluminum, copper, gold, silver, platinum, and steel.

[0069] Step 203: selecting a substrate 106 material and preparing the substrate 106, wherein the substrate 106 is a base layer;

[0070] Step 204: preparing a waveguide structure with a forward phase velocity, and transferring the structure onto a waveguide structure with a reverse phase velocity, thereby constructing a gate voltage structure 105;

[0071] The cross section of the waveguide structure with the forward phase velocity can be square, rod-shaped, ellipsoidal or other structures; its geometric size is 100nm-100um, and its thickness is 3nm-600nm.

[0072] The material of the waveguide structure with the forward phase velocity includes graphene, black phosphorus, silver, iron, copper, aluminum, graphite, and transition metal sulfide.

[0073] Step 205: Transfer the metal antenna onto the entire device, and couple the incident far-field light to the optical switch device to excite the polariton mode.

[0074] The exciting polaritons mode includes: using incident light to illuminate the antenna 101 to excite polaritons in the waveguide at the boundary.

[0075] Step 206: changing the gate voltage to achieve a continuous change of the device from the on state to the off state.

[0076] In a specific embodiment, the dispersion diagrams of hybrid polaritons in the overlap region of positive and negative phase velocity waveguides under different gate voltages are as follows: Figure 3 As shown, it is shown that the hybrid polariton band gap position is effectively regulated by the gate voltage. The device supports the forward phase velocity of graphene polaritons and the reverse phase velocity of molybdenum oxide polaritons. In the overlapping area of ​​graphene and molybdenum oxide, dispersion splitting can be achieved to generate a band gap. By regulating the size of the graphene gate voltage, the band gap position can be effectively controlled.

[0077] In a specific embodiment, COMSOL is used to simulate the on-off of polaritons in waveguide transmission at different Fermi levels. Figure 4(a)-Figure 4(c) As shown, Figure 4(a) shows the COMSOL simulation cross-section of polariton waveguide transmission at Fermi level 0eV-0.3eV. Figure 4(b) shows the intensity distribution of polariton transmittance at different Fermi energies. Figure 4(c) shows the calculated switching ratio of the electrically controlled polariton switch device at Fermi energy 0eV-0.6eV.

[0078] In a specific embodiment, the near-field diagram of an electrically controlled polariton switch device based on positive and negative phase velocity waveguide hybrid coupling is experimentally demonstrated as follows: Figure 5(a)-Figure 5(b) As shown in Figure 5(a), the structured light field diagram of the electrically controlled polariton switch device is shown. Figure 5(b) shows the near-field intensity diagram of the polariton waveguide under the controlled electrical gate voltage. As the gate voltage changes from 0V to -8V, the polariton near-field signal is gradually turned off.

[0079] In the specific implementation, the experimental data results of the near-field signal extracted in the experiment and the transmittance and switching ratio are shown in the figure Figure 6(a)-Figure 6(b) As shown, Figure 6(a) shows the experimental extraction intensity of the near-field signal of the electrically controlled polaritonic switching device as the Fermi energy changes. Figure 6(b) shows the experimental distribution of the near-field signal transmittance and switching ratio of the electrically controlled polaritonic switching device as the Fermi energy changes.

[0080] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0081] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An electrically controlled polariton switching device based on positive and negative phase velocity waveguide hybrid coupling, characterized in that: include: Antenna, forward phase velocity waveguide, reverse phase velocity waveguide, substrate, signal detection device and grid voltage structure; the antenna, forward phase velocity waveguide and signal detection device are all connected to the reverse phase velocity waveguide, the reverse phase velocity waveguide is connected to the substrate, and the grid voltage structure is respectively connected to the substrate and the forward phase velocity waveguide.

2. The electrically controlled polariton switching device based on positive and negative phase velocity waveguide hybrid coupling according to claim 1, characterized in that: The signal detection device is a scattering type scanning near-field optical microscope needle tip, which is used for signal detection.

3. The electrically controlled polariton switching device based on positive and negative phase velocity waveguide hybrid coupling according to claim 2, characterized in that: It also includes exciting polaritons in the waveguide at the boundary using an incident electromagnetic wave to illuminate the antenna.

4. The electrically controlled polariton switching device based on positive and negative phase velocity waveguide hybrid coupling according to claim 3, characterized in that: The incident electromagnetic wave is concentrated in the infrared region, with a wavelength range of 970-8000cm -1 .

5. The electrically controlled polariton switching device based on positive and negative phase velocity waveguide hybrid coupling according to claim 3, characterized in that: The polaritons in the waveguide are transmission-type polaritons.

6. The electrically controlled polariton switching device based on positive and negative phase velocity waveguide hybrid coupling according to claim 5, characterized in that: The gate voltage structure is used to adjust the positive and negative phase velocity waveguide hybrid coupling coefficients by changing the carrier concentration of the forward phase velocity waveguide, thereby controlling the transmission on and off of the transmission-type polariton waveguide.

7. A method for preparing an electrically controlled polariton switch device based on positive and negative phase velocity waveguide hybrid coupling, characterized in that: include: By utilizing the hybrid coupling of polaritons with opposite phase velocities, spontaneous symmetry breaking of the system is induced to generate a polariton bandgap. By adjusting the electrical gate voltage of the gate structure and regulating the bandgap position, the polariton is dynamically transformed from the on state to the off state.

8. The method for preparing an electrically controlled polariton switch device based on positive and negative phase velocity waveguide hybrid coupling according to claim 7, characterized in that: The preparation method comprises: S1: Preparation of waveguide structure with reverse phase velocity; S2: Select the shape and size of the antenna and make the antenna; S3: Selecting a substrate material and preparing the substrate; S4: preparing a waveguide structure with a positive phase velocity, and transferring the structure to a waveguide structure with a reverse phase velocity to construct a gate voltage structure; S5: placing the antenna on the switch device, coupling the incident far-field light to the optical switch device, and exciting the transmission-type polaritons mode; S6: Change the gate voltage to control the continuous change of the device from the on state to the off state.

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