CN119511601A - A double-layer optical cryptographic device and method based on room temperature polariton condensation - Google Patents

Abstract

Translated fromChinese

一种基于室温极化激元凝聚的双层光学密码装置及方法。它主要包括泵浦光路、室温激子极化激元凝聚载体和信号采集终端三部分，第一部分主要包括飞秒脉冲激光器、光学参量放大器和空间光调制器，第二部分主要包括引入光路和样品仓，第三部分主要包括图像和光谱分析终端。首先，泵浦光路部分产生特定波长、重频和光场强度分布的飞秒脉冲泵浦光；随后，将泵浦光引入到具有圆盘形势阱结构的样品上，产生激子极化激元凝聚态；最后，通过图像与光谱分析终端得到该凝聚态发光的强度分布和光谱分布。由凝聚态的强度分布和光谱分布可以形成一组特定的对应关系，实现双层密码功能。本装置原理特殊，通过调控光场即可简单实现，是一种新形式的光学密码形式。

A double-layer optical cryptography device and method based on room-temperature polariton condensation. It mainly includes three parts: a pump optical path, a room-temperature exciton-polariton condensation carrier, and a signal acquisition terminal. The first part mainly includes a femtosecond pulse laser, an optical parametric amplifier, and a spatial light modulator. The second part mainly includes an introduction optical path and a sample chamber. The third part mainly includes an image and spectrum analysis terminal. First, the pump optical path generates a femtosecond pulse pump light with a specific wavelength, repetition rate, and light field intensity distribution; then, the pump light is introduced into a sample with a disk potential well structure to generate an exciton-polariton condensate state; finally, the intensity distribution and spectral distribution of the condensate state light are obtained through the image and spectrum analysis terminal. A set of specific corresponding relationships can be formed by the intensity distribution and spectral distribution of the condensate state to realize the double-layer cryptography function. The principle of this device is special and can be simply realized by regulating the light field. It is a new form of optical cryptography.

Description

Double-layer optical password device and method based on room temperature polariton condensation

Technical Field

The invention mainly relates to the fields of halide perovskite materials, condensed state physics, semiconductor microcavities, spectrum space and signal processing, in particular to methods such as formation of room-temperature exciton polariton vitreous color-Einstein condensation in the semiconductor microcavities, detection of stimulated radiation images, regulation and control technology of light field intensity distribution and the like.

Technical Field

Exciton polaritons are quasi-particles produced by strong coupling of excitons and photons in a semiconductor microcavity. The characteristics of photons and particles are combined, and a unique semi-light semi-substance mixed state is formed. The quasi-particles take a significant role in the field of basic science and in novel photoelectric and quantum technologies. In exploring basic physics, exciton polaritons are considered ideal targets for studying the room temperature bose-einstein condensation (BEC) phenomenon due to their low effective mass and boson-to-boson interactions. Since Hopfield first proposed the concept of exciton polaritons in the 50 s of the last century, research on this quasi-particle in microcavities has made significant progress. In 1992, weisbuch and its team were in GaAs planar Quantum Well (QW) microcavities, successful experiments confirmed the presence of cavity excitons, a finding that injected new vitality into this field.

Disclosure of Invention

Aiming at the problems that the traditional password device is easy to crack and is fully digital and has low safety coefficient, the invention provides a double-layer optical password device based on exciton polaritons, and the invention aims to enable a sample to generate glass-Einstein condensation and luminescence under the pumping of femtosecond pulse laser with specific light field intensity distribution through designing a light path, and analyze a password carried in the sample with a disc-type potential well structure through a spectrometer and a charge coupled sensor.

The technical scheme of the invention relates to a double-layer optical password device based on exciton polaritons, which is shown in figure 1, and mainly comprises a femtosecond pulse laser (1), a laser and spatial light modulator control computer (2), an optical parametric amplifier (3), a plane mirror 1 (4), a plane mirror 2 (5), a plane mirror 3 (6), a beam splitter 1 (7), an achromatic planoconvex lens 1 (8), a sample bin (9), a microscope objective (10), a beam splitter 2 (11), an achromatic planoconvex lens 2 (12), a square diaphragm (13), an achromatic planoconvex lens 3 (14), a charge coupled sensor (15), an image acquisition processing terminal (16), an achromatic planoconvex lens 4 (17), a spectrometer (18), a beam splitter 3 (19), a white light source (20) and a spatial light modulator (21), wherein firstly, illumination white light is generated by using the white light source (20), and the illumination light is irradiated to the sample bin (9) through the beam splitter 1 (7), the achromatic planoconvex lens 1 (8), the beam splitter 2 (11) and the microscope bin (10), then the sample is coupled to the surface of the sample (9) and the charge coupled to the sample amplifier (15), the laser and the spatial light modulator control computer (2) control the laser to generate femtosecond pulse laser, the femtosecond pulse laser is modulated to a proper wavelength and then irradiates the laser to a liquid crystal display screen of the spatial light modulator (21) through the plane reflector 1 (4) and the plane reflector 2 (5), at the moment, the laser and the spatial light modulator control computer (2) load a series of different holograms on the spatial light modulator (21), after the control by software, the light intensity distribution of diffraction spots after passing through the spatial light modulator (21) can be regulated and controlled, the modulated femtosecond pulse laser irradiates the sample surface of the sample bin (9) through the reflector 3 (6), the beam splitter 1 (7), the achromatic plano-convex lens 1 (8), the beam splitter 2 (11) and the microscope objective lens (10), fluorescent light with a specific pattern is generated on the sample surface, the fluorescent pattern is filtered through a 4f system consisting of the achromatic plano-convex lens 2 (12) and the achromatic plano-convex lens 3 (14), the square aperture (13) between the fluorescent pattern is filtered, the square aperture is subjected to a light-diffraction pattern through the achromatic plano-convex lens (19) and then is subjected to optical-beam-splitting (17) detection by the achromatic plano-convex lens (14), the optical-convex lens is subjected to optical-beam-splitting sensor (17) and then is subjected to optical-beam-splitting (17) spectral-coupling, the optical-coupling spectral-coupling is carried out, the optical charge is carried out by the optical-coupling device (17), an image acquisition processing terminal (16) processes real space and spectrum space signals collected by the charge coupled sensor (15) and the spectrometer (18). The femtosecond pulse laser (1) and the optical parametric amplifier (3) are controlled by the laser and the spatial light modulator control computer (2) to output femtosecond pulse laser with certain wavelength and repetition frequency, and output energy is adjusted to enable a sample in the sample bin to reach a pumping threshold value, so that glass-Einstein condensation is generated at room temperature.

By controlling the hologram loaded on the spatial light modulator (21), the intensity distribution of the optical field of the pump light at the surface of the sample in the sample bin (9) is regulated, and the regulated pump light can generate exciton polariton condensation of different modes in the same disc type sample, and the different condensation modes are in one-to-one correspondence in real space and spectral space and are repeatable. The double-layer cipher device is designed by taking a first layer as a pattern layer, collecting real space distribution images of different exciton polariton aggregation modes, setting the patterns with specific characteristics of petal distribution in the images as a first layer cipher, taking a second layer as a spectrum space layer, collecting spectrum space fluorescent signals of different exciton polariton aggregation modes, and setting the central wavelength of the strongest emission peak as a second layer cipher, thereby forming the double-layer cipher device and further realizing an optical cipher function.

The principle of the invention is as follows:

(1) Generation of exciton polarized excimer BEC

The concept of bose-einstein condensation (BEC) was originally developed and proposed by einstein based one of the early works of bose, indicating that an infinite number of bosons can be concentrated in the lowest energy state of the system. In a boson system with no interaction and a dimension of more than two, when the density of the bosons reaches a critical density (ncrit) at a certain temperature, all states are filled, and the bosons continuously added into the system are all gathered in the ground state of the system to form BEC. Or under a certain particle density, when the temperature is reduced to a critical temperature (Tcrit), the state number of the system is reduced to saturation, and redundant particles form BEC after continuing to reduce the temperature. BEC is a macroscopic coherent state consisting of homomorphic microscopic particles and can be seen as a wave of matter consisting of a large number of particles. ncrit and Tcrit increase and decrease with increasing boson mass, respectively, i.e. BEC is easier to achieve in boson systems with smaller mass. In 1995, cornell, wieman and Ketterle observed the BEC phenomenon for the first time by cooling the thin atom vapor to a temperature of about 100nK and obtained the nobel physics prize in 2001. Excitons have a much smaller effective mass than atoms, and in theory BEC can be achieved at higher temperatures, even at room temperature. However, excitons are dissipative systems, excited bright excitons annihilate and radiate photons less quickly than cooling to the lattice temperature, and thermal equilibrium cannot be reached, while dark excitons are difficult to detect because they do not emit light, and exciton BEC is eventually realized in indirect exciton systems. Microcavity exciton polaritons have a much smaller effective mass than excitons, and it is thus possible to achieve BEC at higher temperatures.

(2) Bose-Einstein condensation based on lower branch exciton polaritons

Exciton polaritons are quasi-particles formed by coupling an exciton field and a photon field with each other, and since the exciton-photon coupling problem is quadratic, the Hamilton amount H of the diagonalized exciton polaritons can be resolved to be:

Wherein,To reduce the Planck constant, k represents the wave vector, ω_X (k) and ω_C (k) represent the dispersion of the exciton field and photon field, respectively, and the coupling between excitons and photons can be described by the element Ω_R in the matrix, called Rabi cleavage.

The eigenvalues of this matrix are given by the following equation, namely:

From the above formula, it is apparent that we can obtain two dispersion relations of exciton polaritons, namely:

Omega_UP (k) and omega_LP (k) in the above formula respectively represent the dispersion relation of the upper branch and the lower branch of the exciton polariton, and the Bose-Einstein condensation of the exciton polariton refers to the condensation of the lower branch exciton polariton, and the vortex superposition state of the exciton polariton is formed by the lower branch exciton polariton.

(3) Vortex light preparation based on spatial light modulator

A spatial light Modulator (SPATIAL LIGHT Modulator, SLM) can change the phase, amplitude, polarization state of an incident light beam, and is an optical modulation device. The principle is that firstly, a computer is utilized to simulate the hologram of a target light beam, then the hologram is converted into voltage signals after gray level conversion and is loaded on a liquid crystal display, the external voltage can change the direction of liquid crystal molecules, so that the birefringence of the liquid crystal is controlled to realize the phase modulation effect on light waves, and when initial incident light is injected into the display, the emergent light is the target light beam. The magnitude of the phase adjustment angle of each pixel point of the surface of the spatial light modulator is proportional to the distance that the light beam passes through in the liquid crystal layer, and the adjustment angle of each liquid crystal molecule in the liquid crystal layer is equal to the product of the voltage of the pixel point and the distance. Thus, the total phase modulation for each pixel point (x, y) can be expressed as:

The phase modulation parameter delta phi_x,y(V)＝φ_x,y(V)-φ_x,y (0) depends on the position of the pixel point and the corresponding control voltage; Is a constant representing the phase compensation for each pixel.

The working principle of the SLM is explained below by taking a gaussian beam as an example:

If the beam waist radius of a gaussian beam is ω₀, the amplitude expression of the gaussian beam when ω=ω₀ is:

where r₀、θ₀ is the beam polar parameter. The amplitude expression of the hologram pattern loaded on the SLM liquid crystal screen can be written as:

When the hologram obtained by the formula is loaded on the surface of the SLM, the gray value of each pixel point in the picture is converted into the voltage of the corresponding pixel point on the screen of the spatial light modulator, so that the accurate angle regulation and control of liquid crystal molecules are realized, and the aim of regulating the phase of a light beam is fulfilled.

The invention has the main advantages that:

(1) The device has simple structure. The device has the advantages that the positions of all devices in the light path are fixed, the variables are only the power, the frequency and the light field intensity distribution of the femtosecond pulse laser by the control end of the laser and the spatial light modulator, the control is easy, the radiation light is divided into two paths by using the spectroscope, and the two paths are respectively collected by the CCD sensor camera and the spectroscope and transmitted to the image collection processing terminal for analysis and processing, so that the device can simultaneously detect real space patterns and spectrum space signals, and the influence of the complexity of the light path on detection equipment is reduced.

(2) The device has wide application range. Different passwords can be constructed according to different sample potential well structures, meanwhile, the light field intensity of the pump light can be flexibly and variously changed through the spatial light modulator, and the diversity of the passwords is determined by the diversity of the sample mechanism design and the light field intensity distribution, so that the method is applicable to various occasions needing encryption.

(3) The device has high confidentiality and security. Firstly, a sample with a special potential well structure needs to be obtained, secondly, the optical path shown in fig. 1 is needed, the special light intensity distribution of laser is regulated, so that the code carried by the sample can be analyzed, and the double-layer code combining the pattern and the number is designed according to the real space and the k space, so that the safety is further improved.

Drawings

FIG. 1 is a schematic diagram of a detection device;

FIG. 2 is a schematic view of a disc-shaped perovskite sample under a microscope;

FIG. 3 shows a lasing pattern for a first excitation mode;

FIG. 4 is a spectral diagram of a first excitation mode;

FIG. 5 shows a lasing pattern for a second excitation mode;

FIG. 6 is a spectral diagram of a second excitation mode;

FIG. 7 shows a third excitation pattern of excitation modes;

FIG. 8 is a spectral diagram of a third excitation mode;

Detailed description of the preferred embodiments

The invention takes spontaneous radiation interference patterns formed by coupling of pulse laser and exciton polaritons in a semiconductor microcavity as a measuring carrier, and comprises the following specific implementation steps:

Firstly, a white light source (20) is used for generating illumination white light, the illumination light irradiates the sample surface of a sample bin (9) after passing through a beam splitter 1 (7), an achromatic plano-convex lens 1 (8), a beam splitter 2 (11) and a microscope objective lens (10), the sample in the sample bin (9) is regulated to the field of view of a charge coupled sensor (15), then a femtosecond pulse laser (1) and an optical parametric amplifier (3) are turned on, a computer (2) is controlled by the laser and the spatial light modulator to generate femtosecond pulse laser, the femtosecond pulse laser is modulated to a proper wavelength and then irradiated onto a liquid crystal display screen of the spatial light modulator (21) after passing through a plane mirror 1 (4) and a plane mirror 2 (5), and at this time, a series of different holograms are loaded on the spatial light modulator (21) by the laser and the spatial light modulator control computer (2), and after software control, the light intensity distribution of diffraction spots after passing through the spatial light modulator (21) can be regulated and controlled.

The modulated femtosecond pulse laser irradiates the sample surface of the sample cabin (9) after passing through the reflecting mirror 3 (6), the beam splitter 1 (7), the achromatic plano-convex lens 1 (8), the beam splitter 2 (11) and the microscope objective lens (10), and excites the sample to generate fluorescent light with a specific pattern on the sample surface. The fluorescent pattern firstly passes through a 4f system formed by an achromatic plano-convex lens 2 (12) and an achromatic plano-convex lens 3 (14), stray light is filtered by a square diaphragm (13) between the achromatic plano-convex lens 2 and the achromatic plano-convex lens, then the stray light is split into two beams by a beam splitter 3 (19), one beam is focused by the achromatic plano-convex lens 4 (17) and then a charge coupled sensor (15) collects real space luminous pattern, the other beam is sent into a spectrometer (18) to detect spectral distribution, and an image collection processing terminal (16) processes real space and spectral space signals collected by the charge coupled sensor (15) and the spectrometer (18). The femtosecond pulse laser (1) and the optical parametric amplifier (3) are controlled by the laser and the spatial light modulator control computer (2) to output femtosecond pulse laser with certain wavelength and repetition frequency, and output energy is adjusted to enable a sample in the sample bin to reach a pumping threshold value, so that glass-Einstein condensation is generated at room temperature.

By controlling the hologram loaded on the spatial light modulator (21), the intensity distribution of the optical field of the pump light at the surface of the sample in the sample bin (9) is regulated, and the regulated pump light can generate exciton polariton condensation of different modes in the same disc type sample, and the different condensation modes are in one-to-one correspondence in real space and spectral space and are repeatable.

Firstly, the cipher features of the device are defined, namely, collecting real space distribution images of different exciton polariton condensation modes, as shown in figures 3, 5 and 7, setting petal distribution in the images as a first layer cipher by using the number of angular petals l and the number of radial layers p of petal-shaped luminescence, collecting spectrum space fluorescence signals of different exciton polariton condensation modes, as shown in figures 4,6 and 8, wherein the cipher features are spectrum peak positions of petal-shaped luminescence, and noticing the number of radial layers corresponding to the first layer cipher, the second layer cipher has a plurality of spectrum peak positions, and setting the central wavelength lambda of an emission peak as the second layer cipher. For example, according to the settings, the first group of passwords corresponding to fig. 3 and 4 are l=2, p=1, λ= 533.932nm, the second group of passwords corresponding to fig. 5 and 6 are l=14, p=2, λ1= 533.499nm, λ2= 539.132nm, and the second group of passwords corresponding to fig. 7 and 8 are l=14, p=4, λ1= 532.609nm, λ2= 533.579nm, λ3= 538.066nm, λ4= 538.031nm.

When the double-layer cipher device is implemented, cipher characteristic values, i.e. parameters of l, p and lambda, are set in advance. When a group of data to be tested is input, firstly, the parameters l and p of the input data image layer are verified, and whether the parameters are identical to the set values or not is judged to be true, and the next step is carried out, otherwise, the parameters are false, and the password is input incorrectly. If the first layer of cipher passes, it is checked whether the number of emission peak positions and the corresponding wavelength are the same as the set value, if so, the true cipher is output, otherwise, the false cipher is output, and the cipher is wrong.

What is not described in detail in the present specification belongs to the prior art known to those skilled in the art.

Claims (4)

1. A dual-layer optical cipher device and method based on room temperature polariton condensation comprises a femtosecond pulse laser (1), a laser and a spatial light modulator control computer (2), an optical parametric amplifier (3), a plane reflector 1 (4), a plane reflector 2 (5), a plane reflector 3 (6), a beam splitter 1 (7), an achromatic plano-convex lens 1 (8), a sample cabin (9), a microscope objective (10), a beam splitter 2 (11), an achromatic plano-convex lens 2 (12), a square diaphragm (13), an achromatic plano-convex lens 3 (14), a charge coupled sensor (15), an image acquisition processing terminal (16), an achromatic plano-convex lens 4 (17), a spectrometer (18), a beam splitter 3 (19), a white light source (20) and a spatial light modulator (21), firstly, an illumination white light is generated by using the white light source (20), the illumination light irradiates the sample surface of the sample cabin (9) after passing through the beam splitter 1 (7), the achromatic plano-convex lens 1 (8), the beam splitter 2 (11) and the microscope objective (10), the sample cabin (9) is subjected to charge coupling the charge coupled to the charge coupled with the charge amplifier (1) and the optical parametric amplifier (1), the laser and the spatial light modulator control computer (2) control the laser to generate femtosecond pulse laser, the femtosecond pulse laser is modulated to a proper wavelength and then irradiates the laser to a liquid crystal display screen of the spatial light modulator (21) through the plane reflector 1 (4) and the plane reflector 2 (5), at the moment, the laser and the spatial light modulator control computer (2) load a series of different holograms on the spatial light modulator (21), after the control by software, the light intensity distribution of diffraction spots after passing through the spatial light modulator (21) can be regulated and controlled, the modulated femtosecond pulse laser irradiates the sample surface of the sample bin (9) through the reflector 3 (6), the beam splitter 1 (7), the achromatic plano-convex lens 1 (8), the beam splitter 2 (11) and the microscope objective lens (10), fluorescent light with a specific pattern is generated on the sample surface, the fluorescent pattern is filtered through a 4f system consisting of the achromatic plano-convex lens 2 (12) and the achromatic plano-convex lens 3 (14), the square aperture (13) between the fluorescent pattern is filtered, the square aperture is subjected to a light-diffraction pattern through the achromatic plano-convex lens (19) and then is subjected to optical-beam-splitting (17) detection by the achromatic plano-convex lens (14), the optical-convex lens is subjected to optical-beam-splitting sensor (17) and then is subjected to optical-beam-splitting (17) spectral-coupling, the optical-coupling spectral-coupling is carried out, the optical charge is carried out by the optical-coupling device (17), an image acquisition processing terminal (16) processes real space and spectrum space signals collected by the charge coupled sensor (15) and the spectrometer (18). The femtosecond pulse laser (1) and the optical parametric amplifier (3) are controlled by the laser and the spatial light modulator control computer (2) to output femtosecond pulse laser with certain wavelength and repetition frequency, and output energy is adjusted to enable a sample in the sample bin to reach a pumping threshold value, so that glass-Einstein condensation is generated at room temperature.

2. The dual-layer optical cryptographic device of claim 1, wherein the pump light source is a femtosecond pulsed light having a wavelength selected to correspond to an energy higher than the exciton energy of the sample in the sample compartment, and the spot diameter of the pump light is about 40 μm.

3. A dual layer optical cryptographic device as in claim 1 or 2 wherein the sample in the sample compartment is CsPbBr₃ material and is etched with a disc-shaped region of 6 μm diameter by positive photoresist.

4. A realization method of a double-layer optical password device based on room temperature exciton polariton condensation is characterized in that the intensity distribution of a pumping light field at the surface of a sample in a sample bin (9) is regulated by controlling a hologram loaded on a spatial light modulator (21), the regulated pumping light can generate exciton polariton condensation of different modes in the same disc type sample, and the different condensation modes are in one-to-one correspondence in a real space and a spectral space and are repeatable. The double-layer cipher device comprises a first layer, a second layer, a third layer and a fourth layer, wherein the first layer is a pattern layer, real space distribution images of different exciton polariton condensation modes are collected, patterns with specific characteristics of petal distribution in the images are set to be first layer ciphers, the second layer is a spectrum space layer, spectrum space fluorescence signals of different exciton polariton condensation modes are collected, and the center wavelength of the strongest emission peak is set to be second layer ciphers.