Diffraction Intensity Research Articles

Dynamically controllable two-color electromagnetically induced grating via spatially modulated inelastic two-wave mixing

A scheme for controlling two-color electromagnetically induced grating (TCEIG) in a coherently prepared cold atomic ensemble with a four-level inverted Y-type configuration is proposed via exploiting inelastic two-wave mixing process. By adding an intensity mask behind the auxiliary control field, the transmission functions of the incident probe field and the generated signal field are modulated periodically, thereby leading to the formation of TCEIG. Using experimentally achievable parameters, both the probe and signal fields with different frequencies can be simultaneously diffracted into high-order diffractions. It is found that the diffraction efficiencies of TCEIG, especially the first-order diffraction efficiency, can be significantly improved via adjusting the detunings of the probe and signal fields. Furthermore, it is also demonstrated that the diffraction of TCEIG can be manipulated via tuning the intensity and detuning of the control field. Finally, we investigate the influence the phase mismatch on the diffraction of TCEIG. It is shown that the diffraction pattern of the probe field is rather robust against the phase mismatch, while the diffraction intensities of the signal field are suppressed by the phase mismatch. Our scheme may provide a possibility for the all-optical control of optical switch and wavelength division multiplexing.

An X-ray diffraction study of the influence of linear and changing strain paths on strain and texture evolution in AA6111-T4 aluminium alloy sheets

Multi-stage automotive stamping processes involve both linear and changing strain paths. While extensive research exists on linear strain paths and discontinuous strain path change, the study of continuous strain path change is limited due to the need for sophisticated experimental procedures. In this paper, the effect of continuous strain path change on strain, strain hardening behaviour, microstructure, and texture evolution was compared with that of discontinuous strain path change in AA6111-T4 aluminium alloy using a novel experimental setup comprising an in-situ mechanical rig and cruciform sample. An X-ray source was used to obtain diffraction patterns, which were analysed to measure diffraction intensities and lattice strains at the {111}, {200}, {220} and {311} lattice planes to study strain hardening behaviour, microstructure, and texture evolution during the loading paths. The experiments were repeated outside the X-ray diffraction chamber to study macroscopic strain evolution and hardening behaviour of the samples using a digital image correlation system. It was found that the absence of unloading and reloading in the continuous strain path change posed challenges for plastic deformation in the next deformation stage, leading to strain softening, premature failure, and relatively weaker textural development. Conversely, the presence of unloading and reloading in the discontinuous strain path change facilitated increased plastic deformation in the next deformation stage, resulting in strain hardening, delayed failure, and stronger textural development.

Differential phase contrast intensity diffraction tomography.

Intensity diffraction tomography (IDT) is a label-free computational microscopy technique that infers 3D refractive index (RI) and absorption distributions of objects from intensity-only measurements. Nevertheless, the inherent coherent image formation model requires sequential intensity measurements under various plane wave illuminations, resulting in time-consuming data acquisition and low imaging speed. In this Letter, we propose differential phase contrast intensity diffraction tomography (DPC-IDT), which leverages partially coherent illumination to extend the accessible spectrum range, thereby achieving high-speed, motion-free 3D tomographic microscopy. DPC-IDT integrates DPC illumination within the IDT framework, allowing 3D RI tomogram reconstruction from only four intensity images under matched asymmetric annular illumination. The effectiveness of DPC-IDT is experimentally validated by RI measurements of standard microspheres. We also demonstrate dynamic 3D imaging results of living PLC cells at a 25 Hz volume rate, highlighting its potential for high-speed biological imaging of unstained samples.

Relationship Between Aberration Coefficients of an Optical Device and Its Focusing Property

The best focus point of a focused Gaussian beam subject to a phase aberration is generally shifted with respect to the focal plane of the focusing lens. This focus shift is attributed to a lensing effect that belongs to the phase aberration, which mean focal length can be determined from the aberration coefficients determined in the framework of a Zernike polynomial decomposition. In this paper, we have checked the validity of this procedure, already available in literature, applied to three aberration types: a pure primary spherical aberration, the Kerr effect induced by a Gaussian beam, and an axicon illuminated by a Gaussian beam. Note that usually, the mean focal length of an aberrated lens is based on the relation between the effective radius of curvature of the wavefront before and after the lens. However, in this paper, the focal length associated with the phase aberration under study is defined from the point of the best focus, where the diffracted intensity on the axis is the maximum.

Elucidating the microstructural and optoelectronic properties evolution of sputtered Al-doped MZO thin films

This study involves the deposition of magnesium-doped zinc oxide (MZO) thin films through radio frequency (RF) magnetron sputtering, followed by annealing at temperatures of 350 °C, 450 °C, and 550 °C. Since there is no significant impact of annealing temperatures on MZO thin films, MZO and aluminium-doped zinc oxide (AZO) were co-sputtered to deposit Al-doped MZO (AMZO) thin films. The grown AMZO films were subsequently annealed at 350 °C, 450 °C and 550 °C to regulate their microstructural and optoelectronic characteristics. The X-ray diffraction (XRD) analysis revealed that AMZO films exhibited a predominant (0 0 2) orientation with a single intense diffraction peak, showcasing a wurtzite structure. The field emission scanning electron microscopy (FESEM) presented an increment in grain size for MZO and AMZO films from 31.3 to 64.7 nm and 57.0–64.8 nm, respectively. Furthermore, the atomic force microscopy (AFM) analysis demonstrated a substantial reduction in surface roughness from 1.67 to 1.58 nm for AMZO films annealed at 550 °C compared to MZO films. Notably, the optical band gap changed from 3.64 to 3.32 eV, which was influenced by both the Al content and annealing temperature. The carrier concentration for as deposited and annealed MZO films remained in the orders of 1014 cm−3, whereas AMZO and AMZO films annealed at 550 °C exhibited higher carrier concentrations, in the orders of 1016 cm−3 and 1020 cm−3, respectively. Remarkably, low resistivity (2.10 × 10−2 Ω cm) was observed for AMZO films annealed at 550 °C. Based on these findings, AMZO films exhibited prospect as a buffer layer for CdTe thin films solar cell applications.

X-ray crystallographic diffraction study by whole powder pattern fitting (WPPF) method: Refinement of crystalline nanostructure polymorphs TiO2

High crystalline preferred oriented low strain anatase utilizing a novel and unique approach employing the powder X-ray diffraction (XRD) technique is the prime focus of the investigation. This process effectively enhanced controlled crystalline phase growth with 86.70 % anatase and 13.30 % rutile confirmed through Rietveld refinement in the WPPF method. The prominent crystalline phase providing insights into lattice parameters a = b = 3.7882 Å, c = 9.5143 Å, α=β=γ= 90.0° where lattice strain 0.280 %, lattice volume 136.533 Å3, specific surface area 84.69 m2/g, dislocation density 2.94 × 10–3 nm−2, morphology index 0.722, preference growth -0.087 and packing efficiency 70.13 %. The most intense diffraction was attributed to the (101) plane at 2θ= 25.288° The average crystallite size through various models was 18.45 nm (Scherrer equation), 34.08 nm (Williamson-Hall plot), 22.12 nm (Monshi-Scherrer model), 18.49 nm (Sahadat-Scherrer model), 22.44 nm (Size-strain plot model) and 17.87 nm (Halder-Wagner model) confirming the formation of nano-sized anatase phase of titanium dioxide nanoparticles. The standard powder nanocrystals exhibit a crystallinity of 67.87 %, underscoring the efficacy of the highly oriented anatase with desirable structural and diffraction properties. `This reduction in crystal structure defects and strain, alongside a smaller lattice volume improved stability and high crystalline anatase predominant (101) was observed at low temperatures.

Unveiling the role of temperature on structural, compositional, morphological, thermal and optical properties of hydrothermally synthesized SnS2 nanostructures

Recently, the layered metal dichalcogenides (LMDs) such as tin disulfide (SnS2) has engrossed significant attention because of their n-type semiconducting tunable properties. A hydrothermal method was employed for the synthesis of SnS2 nanostructures by varying reaction temperatures i.e. 160, 170 and 180 °C. To determine the crystallographic, micro-structural, morphological, elemental compositions, thermal and optical properties of the prepared samples, various characterizations such as XRD, Raman spectroscopy, FTIR, FESEM, EDS XPS, TGA, PL and UV spectroscopy were employed. The structural analysis revealed the hexagonal phase formation of prepared SnS2 nanostructures with space group symmetry of P63mc (layer group no.: 186) in all the prepared samples. The sample prepared at 160 °C also exhibit orthorhombic crystal phase of SnS along with SnS2 crystal phase. The intensity of diffraction peaks increased with rise in growth temperature which infers the crystallinity improvement and crystallite size growth. Raman and FTIR spectroscopy also confirm the formation of SnS2 phase in synthesized samples. FESEM analysis showed the development of hexagonal shaped nanostructures for all the prepared samples. Elemental analysis showed the improvement of stoichiometry of SnS2 with increase in reaction temperature. XPS results inferred the existence of Sn and S with +4 and −2 energy states respectively, confirmed the formation of SnS2. The optical property analysis shows the emission in visible region. Furthermore, the band gap values get decreased i.e. 2.42 eV–2.34 eV with increase in growth temperature. Also, the refractive index of the synthesized samples was determined by various empirical models. The improvement of linear optical susceptibility (χ(1)), nonlinear refractive index (n2) and nonlinear optical susceptibility (χ(3)) suggest the usefulness of synthesized nanostructures in optical and photonic applications. Engineering of different properties of SnS2 nanostructures with reaction temperatures suggests the potential usage of these nanostructures for optoelectronic applications.

Nanoscale Ga/Al substituted yttrium iron garnet films by liquid phase epitaxy

Yttrium iron garnet (YIG) has minimum damping factor and low ferromagnetic resonance (FMR) linewidth, making it a preferred material for low loss microwave and spintronic devices. The saturation magnetization of YIG is 1750 Gauss, and for low-frequency devices, a lower saturation magnetization is more suitable. Ga3+ and Al3+ are with smaller radii and non-magnetic moment, so the substitution of Ga3+ and Al3+ can decrease saturation magnetization. Here, 4.8–193.7 nm ultra-thin Y3(GaAlFe)5O12 garnet (GaAl-YIG) monocrystalline films are prepared on gadolinium gallium garnet (GGG) substrates by using the liquid-phase epitaxy (LPE) method. As expected, these films exhibit a low saturation magnetization of almost less than 100 Gauss, while their FMR linewidth remains at levels close to that of YIG. The films show a (111) orientation and in a state of tension, and the diffraction intensity of the films get stronger as films thickness increases. The free energy and density of states are calculated for different Ga/Al substitution position by density functional theory simulations. The elements show a different diffusion distance in the GaAl-YIG/GGG interface, and the variation of magnetization properties with interface width are analyzed. The surface roughness of the films is only a few angstroms. The damping factor of these ultra-thin films are on an order of 10−4 except the 4.8 nm film, which suggests that the minimum thickness of the garnet film with good performance by using the LPE method is about 10 nm. According to the analysis of structure and magnetization properties, it demonstrates that the LPE method has potential to provide nanoscale garnet films for low loss microwave and spintronic devices.

High‐Speed High‐Resolution Transport of Intensity Diffraction Tomography with Bi‐Plane Parallel Detection (Laser Photonics Rev. 18(11)/2024)

High‐Speed High‐Resolution Transport of Intensity Diffraction Tomography with Bi‐Plane Parallel Detection (Laser Photonics Rev. 18(11)/2024)

Mapping domain structures near a grain boundary in a lead zirconate titanate ferroelectric film using X-ray nanodiffraction.

The effect of an electric field on local domain structure near a 24° tilt grain boundary in a 200 nm-thick Pb(Zr0.2Ti0.8)O3 bi-crystal ferroelectric film was probed using synchrotron nanodiffraction. The bi-crystal film was grown epitaxially on SrRuO3-coated (001) SrTiO3 24° tilt bi-crystal substrates. From the nanodiffraction data, real-space maps of the ferroelectric domain structure around the grain boundary prior to and during application of a 200 kV cm-1 electric field were reconstructed. In the vicinity of the tilt grain boundary, the distributions of densities of c-type tetragonal domains with the c axis aligned with the film normal were calculated on the basis of diffracted intensity ratios of c- and a-type domains and reference powder diffraction data. Diffracted intensity was averaged along the grain boundary, and it was shown that the density of c-type tetragonal domains dropped to ∼50% of that of the bulk of the film over a range ±150 nm from the grain boundary. This work complements previous results acquired by band excitation piezoresponse force microscopy, suggesting that reduced nonlinear piezoelectric response around grain boundaries may be related to the change in domain structure, as well as to the possibility of increased pinning of domain wall motion. The implications of the results and analysis in terms of understanding the role of grain boundaries in affecting the nonlinear piezoelectric and dielectric responses of ferroelectric materials are discussed.

Optical parameter design model of hemispherical laser retroreflector arrays for satellite laser ranging.

A laser retroreflector array (LRA) with multiple retroreflectors is used to directionally reflect an incident laser beam and aims to enhance the received signal strength into laser ranging ground stations. A comprehensive mathematical equation of the received photons is established by modelling the LRA far field diffraction intensity (FFDI) and the satellite velocity aberration position. Based on this received photon model, a novel method on designing the dihedral angle offset and the aperture of retroreflectors is proposed, which maximizes the received photon under the minimal elevation angle of the ground station. Taking the hemispherical structure parameters of Chinese HY-2 satellite LRA and the specification parameters of the Shanghai Astronomical Observatory, the optimal aperture and the dihedral angle offset of the HY-2 laser retroreflectors are 17 mm and 1.6″, respectively. These two optimal optical parameters make the received photon under the elevation angle of 0° reach ∼0.9 count per laser shot. Until now, ∼851,400 successful observations have been successfully obtained by global ground stations since the first launch of HY-2 satellite series in 2011, which guarantees the high-precise orbit determination of HY-2 satellite series.

Particle size and band gap evaluation of green gold nanoparticles (AuNPs) with potential applications

Abstract The present study was aimed towards green synthesis of gold nanoparticles (AuNPs) using fungal strain (SGSK-7) with assessment of their size using different techniques viz., X-ray diffractormeter, Dynamic light scattering, Atomic force microscopy, FE-Scanning Electron Microscopy and Fourier transform Infrared Spectroscopy. The intense characteristic diffraction peaks at angle 2Ѳ (38.13˚) presented the crystalline nature of the reduced gold solution and calculation of crystalline size (12 nm) using Scherer’s equation further confirmed synthesis of gold nanoparticles while dynamic light scattering analysis indicated the particle size range of gold nanoparticles between 2 nm to 50 nm. Field Emission Scanning Electron Microscopic (FESEM) and Atomic Force Microscopy (AFM) analysis of extracellular gold nanoparticles depicts spherical shape of AuNPs of approximately 40 nm. Fourier transform Infrared (FTIR) Spectroscopy depicted the presence of the gold nanoparticles along with the other biomolecules secreted by fungus which plays vital role in reduction, capping and stabilization of gold nanoparticles. Energy dispersive X-ray, mapping analysis, Zeta potential and UV-Vis spectrophotometery analysis further confirmed the presence and stability of gold nanoparticles, respectively. Zeta potential of gold nanoparticles leads to conclude the neutral nature (-10 mV to 10mV) of the particles. The UV-Visible spectrophotometeric analysis also confirmed the formation of gold nanoparticles with an absorption peak at 547 nm. On the basis of UV-Visible spectra the optical band gap of 2.44 eV is examined. The phylogenetic relatedness of SGSK-7 revealed 99% homology with Aspergillus tamari after sequencing of the ITS region followed by BLAST.

Preparation and Characterization of Nanostructured ITO Thin Films by Spray Pyrolysis Technique: Dependence on Annealing Temperature

Transparent conducting oxides (TCOs) like Indium tin oxide (ITO) have wide attention from all scientists which have low resistance and high visible light transmittance, used as transparent electrodes in many optoelectronic devices such as liquid crystal displays, touch screens, light emitting diodes, and solar cells. In this research, the relationship between the crystallization, optical transmittance, and surface roughness of nanostructured ITO thin films and the change in annealing temperature was investigated. To enhance the efficiency of this material in optoelectronic applications, both the optical transmittance in the visible region and the crystallite size must be increased. These results can be obtained by the heat treatment of the films. Nanostructured ITO thin layer films have been successfully prepared at a substrate temperature equal to (350)℃ by chemical spray pyrolysis (CSP) technique. The physical characterizations of nanostructured ITO thin layer films were investigated at different annealing temperatures (400,450 and 500)℃. The presence of diffraction peaks indicates that the as-deposited and post annealed films are polycrystalline cubic structure and the peak (400) is a preferred growth orientation. For all samples the value of intensity of diffraction peaks increases with increasing substrate temperature. The crystallite size of nanostructured ITO thin films is strongly related to the annealing temperature. The crystallite size estimated from XRD was found to rise with rising annealing temperature. The surface roughness of nanostructured ITO thin layer films increases with rising annealing temperature. High values of transmittance have been measured in the visible region 550 nm equal to (70, 82, 84 and 88)% corresponding to annealing temperature (350,400,450 and 500)℃ respectively.

Dynamic multiplexed intensity diffraction tomography using a spatiotemporal regularization-driven disorder-invariant multilayer perceptron.

Multiplexed intensity diffraction tomography (mIDT) is a technique that reconstructs the three-dimensional refractive index (3DRI) of a sample solely through intensity measurements. Using an array of light sources to generate multi-directional and multiplexed illumination eliminates the need for mechanical scanning, allowing for quantitative 3DRI reconstruction of label-free samples. However, acquiring multiple images under different illumination conditions limits its use in dynamic scenes. Here, we propose a dynamic 3DRI reconstruction method based on a spatiotemporal regularization-driven disorder-invariant multilayer perceptron (STR-DI-MLP). This method reconstructs the 3DRI distribution of a sample from multiple images with motion-induced shifts. Simulations show it offers faster reconstruction speeds and fewer artifacts. Moreover, it maintains robust reconstruction performance under varying degrees of motion. Experimental validation of our system demonstrates its capability to reconstruct 3DRI in dynamic scenes with motion speeds below approximately 16 µm/s, proving it effective for 3DRI reconstruction of living microorganisms.

Effect of chemical bonding and relative density on microwave dielectric properties of LiInW2O8 ceramics

To meet the demands of the growing field of electronic communications, LiInW2O8 ceramics with low dielectric loss (high Q×f) and low dielectric constant (εr) are prepared by a solid phase reaction method. X-ray diffractometry reveals a scheelite single-phase structure for the prepared ceramics. Compared with the standard LiInW2O8, the as-prepared LiInW2O8 has a higher relative diffraction intensity for the (200) crystal plane, indicating an anisotropic growth phenomenon in the present case. Raman spectroscopy and calculations of the P-V-L complex chemical bonding theory show that W-O bonding is a key factor affecting the dielectric properties of LiInW2O8 ceramics. Furthermore, excellent microwave dielectric properties with εr ≈ 14.2, Q×f ≈ 63000 GHz, and τf ≈ −28 ppm/℃ are obtained by sintering the ceramic at 1025°C.

Development of ultrafast four-dimensional precession electron diffraction

Ultrafast electron diffraction/microscopy technique enables us to investigate the nonequilibrium dynamics of crystal structures in the femtosecond-nanosecond time domain. However, the electron diffraction intensities are in general extremely sensitive to the excitation errors (i.e., deviation from the Bragg condition) and the dynamical effects, which had prevented us from quantitatively discussing the crystal structure dynamics particularly in thick samples. Here, we develop a four-dimensional precession electron diffraction (4D-PED) system by which time (t) and electron-incident-angle (ϕ) dependences of electron diffraction patterns (qx,qy) are recorded. Nonequilibrium crystal structure refinement on VTe2 demonstrates that the ultrafast change in the crystal structure can be quantitatively determined from 4D-PED. We further perform the analysis of the ϕ dependence, from which we can qualitatively estimate the change in the reciprocal lattice vector parallel to the optical axis. These results show the capability of the 4D-PED method for the quantitative investigation of ultrafast crystal structural dynamics.

Biosynthesis of antimicrobial nanoparticle from Swertia spp. (Chirayita) against bacterial pathogens of poultry- A way forward to green nanotechnology and nano-medicines

The increasing prevalence of multidrug-resistant microorganisms in poultry has led to a rise in bacterial infections, causing significant economic loss. Green nanotechnology, such as silver nanoparticles (AgNPs), has the potential to address this issue by providing potent antifungal, antiviral, and antibacterial properties. This study explored the combined potential of AgNPs and the local herb Swertia chirayita against established poultry pathogens, employing a non-factorial Central Composite Design (CCD) to evaluate the factors affecting the production of nanoparticles induced by silver nitrate from the selected herb. The optimal values for temperature, wavelength, silver nitrate concentration, incubation duration, and pH were found to produce the highest nanoparticles. The functional groups in Swertia chirayita stimulated nanoparticles were confirmed using FTIR spectroscopy, and the stability of ScNPs was elucidated using zeta potential. The crystalline structure of ScNPs was confirmed using diffraction intensity patterns. Silver nanoparticles demonstrated antibacterial activity against Salmonella spp. and Escherichia coli (E.coli), both known as significant poultry pathogens, using the agar well diffusion method, with inhibition zones of 25.0 mm and 35.0 mm, respectively.This study explored the green manufacturing of silver nanoparticles by using plants and microorganisms, focusing on their antibacterial properties. The exact mechanism of synthesis and action in AgNPs is still poorly understood. Researchers should prioritize the use of accessible, easy-to-extract plants or bacteria, especially non-pathogenic and fast-growing microorganisms for safe handling. Analyzing biomolecules in plant extract, microbial biomass, or culture supernatants, including probiotic bacteria, is crucial for creating and stabilizing AgNPs, which could be effective synthetic agents. It is crucial to optimize conditions for rapid, stable, and large-scale synthesis. Based on this research, Sc-NPs may be proposed as nanomedicine for treating infections in poultry caused by E. coli and Salmonella spp.

On the Piezoelectric Properties of Zinc Oxide Thin Films Synthesized by Plasma Assisted DC Sputter Deposition

AbstractThis work presents a study of piezoelectric zinc oxide (ZnO) thin films deposited by a novel post‐reactive sputtering method. The process utilizes a rotating drum with DC magnetron sputtering deposition onto substrates with subsequent DC plasma‐assisted oxidation of the deposited metal to metal oxide. The paper analyzes the influence of plasmaassisted magnetron sputtering (PA‐MS) deposition parameters (O2 plasma source power, O2 flow, and Ar flow) on the morphological, structural, optical, and piezoelectric properties of ZnO thin films. Design of experiments has been utilized to evaluate the role of these parameters on the growth rate (rg) and the properties of resulting films. Results indicate a predominant influence of the plasma power on the rg over other parameters. Among the eight tested samples, three of them show high crystal quality with high intensity (0001) diffraction peak, characteristic of the wurtzite crystalline structure of ZnO, and one of them exhibits piezoelectric coefficient values of ≈11pC N−1. That sample corresponding to a ZnO film deposited at the lowest rg of 0.075 nm s−1, confirmed the key role of the deposition parameters on the piezoelectric response of films, and demonstrated PA‐MS as a promising technique to produce high‐quality piezoelectric thin films.

Hexagonal Enhanced Porous GaN with Delayed Integrated Pulse Electrochemical (iPEC) Etching

This present study investigates the effect of time delay (Td) on the formation of porous GaN (P-GaN) using integrated pulse electrochemical (iPEC) etching. Porous GaN (P-GaN) was formed by etching an N-type GaN wafer with a 4% KOH electrolyte for 60 minutes under an ultraviolet (UV) lamp at a current density of 80 mA/cm2. A Td of 120 minutes was applied before electrochemically etching the P-GaN sample. The top view image of the field emission scanning electron microscopy (FESEM) revealed a significant difference when a Td was applied. A dense and uniform hexagonal P-GaN was obtained from the Td iPEC sample, while the non-Td sample exhibited a multi-layered hexagonal porous structure with unfinished pore-etched areas. Higher porosity and deeper pores were observed in the Td sample. Intense high-resolution X-ray diffraction (HR-XRD) peak intensity was observed in the Td iPEC sample with a lower full width half maximum (FWHM), indicating that the sample had better crystallinity. The Raman spectra of the sample anodized with a Td exhibited higher Raman peak intensity and a slight shift to a higher frequency concerning as-grown GaN, indicating better crystallinity and a tensile stress relaxation of 0.24 GPa. Post etching, a blue shift of the photoluminescence (PL) peak, from 364 nm (as-grown GaN) to 363 nm (P-GaN), was observed, and a small PL peak started to form around 385 nm compared to the as-grown GaN due to the relaxation of the tensile stress, which modified the bandgap. The PL peak intensity of the Td sample was higher than the non-Td sample, indicating that the porosity and uniformity allowed more light interaction with the material, resulting in more efficient photon absorption and emission. The results indicated that potentially efficient optoelectronics devices can be fabricated on a P-GaN using a combination of electroless and electrochemical etching of the GaN epitaxial layer.

Diffractive Optical Encryption Systems Based on Multiple Wavelengths and Multiple Distances

Coherent diffractive imaging is an optical methodology that encodes information about an object within the diffraction intensity. Here, we introduce a diffractive optical encryption system that utilizes multiple wavelengths and multiple distances, significantly expanding the size of the secret key space and enhancing the overall security of the system by incorporating these parameters as keys. The system adopts single optical path design, compact structure and is easy to implement, overcoming the disadvantage of single key space of traditional encryption system. This system can encrypt images into a series of diffraction intensity maps (i.e., ciphertexts), and exhibits a high sensitivity to minor variations in wavelength or distance during the process of decryption, showing excellent anti-cracking ability. Furthermore, the system also has considerable robustness, ensuring that the information still can be effectively recovered even in instances of partial loss. Numerical simulation results are presented to demonstrate feasibility and effectiveness of the proposed method. Our study provides novel concepts and methodologies to the advancement of optical encryption technology, while also offering significant technical assistance to the domain of information security.