CN112068228B - Plane focusing lens device based on phonon polarized waves - Google Patents

Abstract

The invention provides a plane focusing lens device based on phonon polarized waves, which comprises a substrate layer, a focusing lens and a focusing lens, wherein a molybdenum oxide thin layer is arranged on the substrate layer; covering a metal antenna on one side of the molybdenum oxide thin layer; and irradiating the metal antenna by using scattered light or infrared light to excite hyperbolic phonon excimer, and adjusting the focal length of nano focusing by changing the size of the metal antenna or the wavelength of incident light. The size of the wave vector of the phonon excimer is regulated and controlled by controlling the size of the metal antenna or the wave number of incident infrared light, so that the focal length regulation and control of the planar lens focusing are realized. The method is simple and easy to implement, and has a wider range and lower cost.

Description

A Planar Focusing Lens Device Based on Phonon Polarized Waves

technical field

The invention relates to the technical field of nano-focusing, in particular to a plane focusing lens device based on phonon polarized waves.

Background technique

Molybdenum oxide is a biaxial material and is strongly anisotropic. In different residual ray bands, the dielectric functions along different optical axes are opposite, and the generated phonon polaritons have obvious plane hyperbolic properties, which can control the propagation of light along a special direction, so it can be controlled and regulated in nano-optics. The field of light has important applications.

Hyperbolic phonon polaritons are a special kind of polaritons, which have obvious anisotropy and low loss characteristics compared with other conduction types of polaritons (such as plasmons, excitons). In the prior art, the excitation of intra-chip hyperbolic phonon polaritons can be achieved by relying on natural molybdenum oxide materials.

Constructing a flat lens and realizing nano-focusing has important application value in the fields of micro-nano optics, light control and regulation. In the prior art, people mainly rely on the superstructure, the surface structure of the nano-focusing lens. However, due to the influence of micro-nano processing, large light loss will be caused, and due to the influence of size, the range of concentrated light is relatively narrow. In addition, relying on superstructures to construct nano-focusing lenses on the surface is expensive to manufacture, which is not conducive to practical production applications.

Therefore, in order to solve the above problems, a plane focusing lens device based on phonon polarized waves is required, which can realize the simple and easy focal length control with reduced loss.

SUMMARY OF THE INVENTION

One object of the present invention is to provide a plane focusing lens device based on phonon polarized waves, the device includes a base layer, and a molybdenum oxide thin layer is arranged on the base layer;

A metal antenna is covered on one side of the thin molybdenum oxide layer, and the metal antenna is irradiated with scattered light or infrared light to excite hyperbolic phonon polaritons.

Preferably, the base layer material is an inorganic dielectric material or an organic polymer material.

Preferably, the planar geometric size of the molybdenum oxide thin layer is 1 μm-500 μm, and the thickness is 2 nm-5000 nm; the geometric size of the metal antenna is 10 nm-300 μm, and the thickness is 20 nm-50 μm.

Another object of the present invention is to provide a preparation method of a plane focusing lens device based on phonon polarized waves, the method comprising:

Preparation of molybdenum oxide thin layer;

Select the shape and size of the antenna to make a metal antenna;

A base layer material is selected, a base layer is prepared, a molybdenum oxide thin layer is attached on the base layer, and the metal antenna is covered on one side of the molybdenum oxide thin layer.

Another object of the present invention is to provide a method for adjusting the focal length of nano-focusing based on a plane focusing lens device based on phonon polarized waves, the method comprising:

Step 1), directly irradiating the metal antenna with the scattered light from the tip of the mid-infrared scattering scanning near-field optical microscope to excite the molybdenum oxide phonon polariton;

Obtain the electric field distribution and measure the length of the focal length;

Step 2), changing the size of the metal antenna, repeating step 1), obtaining the electric field distribution, and measuring the length of the focal length;

Step 3), repeat step 2) until the focal length is adjusted to an appropriate position.

Another object of the present invention is to provide a method for adjusting the focal length of nano-focusing based on a plane focusing lens device based on phonon polarized waves, the method comprising:

Step a), irradiating the metal antenna with incident infrared light to excite phonons at the boundary of the metal antenna;

Obtain the electric field distribution and measure the length of the focal length;

Step b), changing the wave number of the incident infrared light, repeating step a) to obtain the electric field distribution, and measuring the length of the focal length;

Step c), repeat step b) until the focal length is adjusted to an appropriate position.

The invention provides a plane focusing lens device based on phonon polarized waves and a method for adjusting the focal length of nano-focusing. By controlling the size of the metal antenna or the wave number of the incident infrared light, the size of the wave vector of the phonon polariton is regulated. To achieve the control of the focal length.

The invention provides a plane focusing lens device based on phonon polarized waves and a method for adjusting the focal length of nano-focusing, which can change the size of the metal antenna and adjust the position of the focal point. The invention provides a plane focusing lens device based on phonon polarized waves and a method for adjusting the focal length of nano-focusing, which can change the wave number of incident infrared light, and can also dynamically adjust the position of the focal length, thereby realizing the focal length adjustment of the plane lens focusing. The invention is simple and easy to implement, has wider scope and lower cost.

It is to be understood that both the foregoing general description and the following detailed description are exemplary illustrations and explanations, and should not be used as limitations on what is claimed in the present invention.

Description of drawings

Further objects, functions and advantages of the present invention will be elucidated by the following description of embodiments of the present invention with reference to the accompanying drawings, wherein:

FIG. 1 schematically shows a schematic structural diagram of a plane focusing lens device based on phonon polarized waves according to the present invention.

FIG. 2 shows the experimental and simulated images of a phonon-polarized wave-based plane focusing lens device of the present invention.

FIG. 3 shows optical microscope pictures of metal antennas of different sizes of a phonon polarized wave-based plane focusing lens device of the present invention.

FIG. 4 shows focused images corresponding to metal antennas of different sizes of a planar focusing lens device based on phonon polarized waves of the present invention.

FIG. 5 shows the focused images of three groups of metal antenna sizes of a phonon polarized wave-based plane focusing lens device of the present invention under the illumination of different incident wave numbers.

FIG. 6 is a schematic diagram showing the relationship between different incident wave numbers and focal lengths of a plane focusing lens device based on phonon polarized waves of the present invention.

FIG. 7 shows a flow chart of a method for adjusting the focal length of nano-focusing based on a planar focusing lens device based on phonon polarized waves in one embodiment of the present invention.

Detailed ways

Objects and functions of the present invention and methods for achieving these objects and functions will be elucidated by referring to the exemplary embodiments. However, the present invention is not limited to the exemplary embodiments disclosed below; it may be implemented in various forms. The essence of the description is merely to assist those skilled in the relevant art to comprehensively understand the specific details of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings, and related technical terms should be well known to those skilled in the art. In the drawings, the same reference numbers represent the same or similar parts, or the same or similar steps, unless otherwise stated.

The content of the present invention will be described in detail below in conjunction with specific embodiments. As shown in FIG. 1, a schematic structural diagram of a plane focusing lens device based on phonon polarized waves of the present invention is shown. According to an embodiment of the present invention, a The sub-polarized wave plane focusing lens device includes a base layer 101 , and a molybdenum oxide thin layer 102 is arranged on the base layer 101 . A metal antenna 103 is covered on one side of the molybdenum oxide thin layer 102, and the scattered light or infrared light illuminates the metal antenna 103 to excite hyperbolic phonon polaritons.

In some embodiments, the metal antenna 103 is directly illuminated by the scattered light from the mid-infrared scattering type scanning near-field optical microscope tip 105 to excite the molybdenum oxide phonon polaritons.

In other embodiments, the metal antenna 103 is illuminated with incident infrared light 104 to excite phonon polaritons at the boundary of the metal antenna 103 .

According to an embodiment of the present invention, the material of the base layer 101 is an inorganic dielectric material or an organic polymer material. For example, in some embodiments, the inorganic dielectric material may be selected from the group consisting of silicon dioxide, silicon, quartz, sapphire, germanium, aluminum oxide, boron nitride, calcium fluoride, magnesium fluoride, gallium arsenide, gallium nitride. In some embodiments, the organic polymeric material may be selected from PET, PMMA, PDMS, and plastics.

The crystal plane orientation of molybdenum oxide is (010). According to the embodiment of the present invention, the planar geometric size of the molybdenum oxide thin layer 102 is 1 μm-500 μm, and the thickness is 2 nm-5000 nm. For example, the length of the molybdenum oxide thin layer 102 ranges from 1 μm to 500 μm, and the width ranges from 1 μm to 500 μm.

The material of the metal antenna 103 can be selected from iron, aluminum, copper, gold, silver, platinum, and steel. The shape of the metal antenna 103 can be a circle, a semi-circle, an ellipse, or a semi-ellipse. The geometric size of the metal antenna 103 is 10 nm-300 μm, and the thickness is 20 nm-50 μm.

In this embodiment, a circular metal antenna (disk) is exemplified as an example. The diameter of the metal antenna is 10 nm-300 μm, and the thickness is 20 nm-50 μm.

By exciting the hyperbolic phonon polariton in molybdenum oxide, the metal antenna is used to realize the focusing of the plane lens, and the focal length is dynamically adjusted by changing the size of the metal antenna or the wave number of the incident light. The incident electromagnetic waves used to excite molybdenum oxide are concentrated in the infrared region, and the main wave number in the region is 400-980 cm ^-1 .

According to an embodiment of the present invention, a preparation method of a plane focusing lens device based on a phonon polarized wave includes:

Preparation of molybdenum oxide thin layer;

Select the shape and size of the antenna to make a metal antenna;

A base layer material is selected, a base layer is prepared, a molybdenum oxide thin layer is attached on the base layer, and the metal antenna is covered on one side of the molybdenum oxide thin layer.

The focusing of a plane focusing lens device based on phonon polarized waves provided by the present invention is analyzed below through specific experiments and simulations.

As shown in FIG. 2 , the experimental and simulated images of a plane focusing lens device based on phonon polarized waves of the present invention are focused.

The plane lens focusing device provided by the present invention excites the phonon polariton of molybdenum oxide through a metal antenna to perform plane focusing. In Figure 2, (a) is a metal antenna with a diameter of 2.4um under the incident wave number of 900cm ^-1 (disk) experimental image, f is the focal length shown in the image. (b) is the experimental image of a metal antenna (half-disk) with a diameter of 2.4um under the incident wave number of 900cm ^-1 , and f is the focal length displayed by the image.

In the embodiment, COMSOL software is used for simulation. In Figure 2, (c) is a simulated image of a metal antenna (disk) with a diameter of 2.4um under the incident wave number of 900cm ^-1 , and f is the focal length displayed by the image. (d) is a simulated image of a metal antenna (half-disk) with a diameter of 2.4um under the incident wave number of 900cm ^-1 , and f is the focal length displayed by the image.

As shown in FIG. 3 , optical microscope pictures of metal antennas of different sizes of a plane focusing lens device based on phonon polarized waves of the present invention. In the embodiment, a picture of a metal antenna with a diameter of 0.5 μm-22 μm is taken by an optical fiber microscope. In Figure 3, the circular white area on the right side is the metal antenna, and the left side is the diameter of the metal antenna.

As shown in FIG. 4 , the focused images corresponding to metal antennas of different sizes of a plane focusing lens device based on phonon polarized waves of the present invention. In the embodiment, under the irradiation of infrared light, under different sizes of metal antennas, phonon polariton focusing is performed. In Figure 4, the left side shows the relationship between the size of the metal antenna and the focus size, and the right side corresponds to the focused image of the plane lens of different metal antennas.

According to Figure 4, by gradually reducing the diameter of the metal antenna, the focal length of the focus is gradually reduced, and the focus is getting closer and closer to the boundary of the metal antenna. Therefore, a plane focusing lens device based on phonon polarized waves provided by the present invention can adjust the focal length by adjusting the diameter of the disk, and the effect is very obvious.

As shown in FIG. 5 , the focused images of three groups of metal antenna sizes of a plane focusing lens device based on phonon polarized waves of the present invention under the illumination of different incident wave numbers. In the embodiment, the focused images of three groups of plane lenses with different incident wave numbers under different metal antenna diameters are given. It can be clearly seen that as the wave number increases, the focal length gradually decreases.

FIG. 6 is a schematic diagram showing the relationship between different incident wave numbers and focal lengths of a plane focusing lens device based on phonon polarized waves of the present invention. Gold is used as the metal antenna, and the diameter of the metal antenna is 100nm, 255nm and 450nm, and the focal length gradually decreases with the increase of the incident light wave number.

The invention provides a plane focusing lens device based on phonon polarized waves, by exciting the hyperbolic phonon polariton in molybdenum oxide, relying on a metal antenna to realize the focusing of the plane lens, and by changing the size of the metal antenna or the wave number dynamics of the incident light Adjust the focus.

According to an embodiment of the present invention, the focal length of nano-focusing is adjusted by changing the size of the metal antenna. Specifically, a method for adjusting the focal length of nano-focusing by using a plane lens focusing device includes:

Step 1. Prepare a thin layer of molybdenum oxide.

Step 2. Select the shape and size of the antenna to make a metal antenna.

Step 3: Select the material of the base layer, prepare the base layer, stick a molybdenum oxide thin layer on the base layer, and cover the metal antenna (metal disc) on one side of the molybdenum oxide thin layer.

Step 4. The metal antenna is directly irradiated by the scattered light from the tip of the mid-infrared scattering type scanning near-field optical microscope to excite the molybdenum oxide phonon polaritons.

Step 5. Obtain the electric field distribution and measure the length of the focal length.

Step 6. Change the size of the metal antenna and repeat step 4 to obtain the electric field distribution and measure the length of the focal length.

Step 7. Repeat step 6 until the focal length is adjusted to an appropriate position.

In some preferred embodiments, the size (diameter of the disk) of the prepared metal antenna changes continuously, so as to continuously adjust the focal length.

FIG. 7 shows a flow chart of a method for adjusting the focal length of nano-focusing based on a planar focusing lens device based on phonon polarized waves in one embodiment of the present invention. According to an embodiment of the present invention, the focal length of nano-focusing is adjusted by changing the incident light wave number of infrared light. Specifically, a method for adjusting the focal length of nano-focusing by using a plane lens focusing device includes:

Step S101, preparing a molybdenum oxide thin layer.

Step S102 , selecting the shape and size of the antenna to manufacture a metal antenna.

Step S103 , selecting a base layer material, preparing a base layer, pasting a molybdenum oxide thin layer on the base layer, and covering the metal antenna (metal disc) on one side of the molybdenum oxide thin layer.

Step S104 , irradiating the metal antenna with incident infrared light to excite phonon polaritons at the boundary of the metal antenna.

In step S105, the electric field distribution is obtained, and the length of the focal length is measured.

According to an embodiment of the present invention, after obtaining the length of the measurement focal length, the method further includes:

Step S106 , changing the wave number of the incident infrared light, repeating step S104 to obtain the electric field distribution, and measuring the length of the focal length.

In step S107, step S106 is repeated until the focal length is adjusted to an appropriate position.

The invention provides a plane focusing lens device based on phonon polarized waves and a method for adjusting the focal length of nano-focusing. By controlling the size of the metal antenna or the wave number of the incident infrared light, the size of the wave vector of the phonon polariton is regulated. To achieve the control of the focal length.

The invention provides a plane focusing lens device based on phonon polarized waves and a method for adjusting the focal length of nano-focusing, which can change the size of the metal antenna and adjust the position of the focal point. The invention provides a plane focusing lens device based on phonon polarized waves and a method for adjusting the focal length of nano-focusing, which can change the wave number of incident infrared light, and can also dynamically adjust the position of the focal length, thereby realizing the focal length adjustment of the plane lens focusing. The invention is simple and easy to implement, has wider scope and lower cost.

Other embodiments of the present invention will be readily apparent to and understood by those skilled in the art in conjunction with the specification and practice of the present invention disclosed herein. The description and examples are to be regarded as exemplary only, with the true scope and spirit of the invention being defined by the claims.

Claims (4)

1. A plane focusing lens device based on phonon polarized waves is characterized by comprising a substrate layer, a focusing lens and a focusing lens, wherein the substrate layer is made of an inorganic dielectric material or an organic polymer material, and a molybdenum oxide thin layer is arranged on the substrate layer;

covering a metal antenna on one side of the molybdenum oxide thin layer; irradiating the metal antenna by scattered light or infrared light to excite hyperbolic phonon excimer, and adjusting the focal length of nano focusing by changing the size of the metal antenna or the wavelength of incident light;

the plane geometric dimension of the molybdenum oxide thin layer is 1-500 mu m, and the thickness is 2-5000 nm; the geometric dimension of the metal antenna is 10nm-300 mu m, and the thickness of the metal antenna is 20nm-50 mu m.

2. A method of making the device of claim 1, the method comprising:

preparing a molybdenum oxide thin layer;

selecting the shape and size of the antenna, and manufacturing a metal antenna;

selecting a substrate layer material, preparing a substrate layer, attaching a molybdenum oxide thin layer on the substrate layer, and covering the metal antenna on one side of the molybdenum oxide thin layer.

3. A method for adjusting the focal length of a nano-focus using the device of claim 1, the method comprising:

step 1), directly irradiating a metal antenna by scattered light of a needle point of a mid-infrared scattering type scanning near-field optical microscope to excite a molybdenum oxide phonon excimer;

obtaining electric field distribution and measuring the length of the focal length;

step 2), changing the size of the metal antenna, repeating the step 1) to obtain electric field distribution, and measuring the length of the focal length;

and 3) repeating the step 2) until the focal length is adjusted to a proper position.

4. A method for adjusting the focal length of a nano-focus using the device of claim 1, the method comprising:

step a), irradiating the metal antenna by using incident infrared light, and exciting phonon excimer at the boundary of the metal antenna;

obtaining electric field distribution and measuring the length of the focal length;

step b), changing the wave number of incident infrared light, repeating the step a) to obtain electric field distribution, and measuring the length of the focal length;

and c), repeating the step b) until the focal length is adjusted to a proper position.

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