Holographic Structures Research Articles

Research of light diffraction on electrically controlled multiplexed multilayer inhomogeneous holographic diffraction structures based on the photopolymerizing compositions with nematic liquid crystals

We presented the developed analytical model of optical radiation diffraction on multiplexed multilayer inhomogeneous diffraction structures formed by the holographic method in photopolymerizing compositions with nematic liquid crystals having smooth optical heterogeneity in the thickness of the layers. By numerical calculation, it was shown that when using an applied electric field with different polarities to the diffraction layers, as well as varying the azimuth of the polarization of the reading beam, the angular selectivity of the diffracted beam can be transformed with a significant shift in angular selectivity, which makes it possible to increase the spectral bandwidth by 4 times compared to conventional multilayer diffraction structures.

High-speed arbitrary pure phase hologram generation method based on a specific multi-phase

This paper presents a novel design method, to the best of our knowledge, for the creation of computer-generated holograms (CGHs) with arbitrary phases based on a specific multi-phase. This approach combines the design, production, and fabrication of holographic phase structures and requires only their assembly according to specific phase values. The arrangement of eight different specific phase values enables the production of 2D and 3D holograms comparable in quality to random phase holograms obtained through optimized Gerchberg–Saxton (GS) algorithms and requires only one-sixth of the computational time. The results of simulations and experiments indicate that this method provides a convenient approach to designing, processing, manufacturing, and reproducing high-quality phase holograms. It has the potential for widespread use in holography.

Modulation of H atom photoelectron momentum distribution by chirped laser pulses of different wavelengths

The wavelength dependence of the holographic interference structure in the photoelectron momentum distribution (PMD) of hydrogen atoms under a few-cycle chirped laser field is investigated using a two-dimensional (2D) semiclassical two-step (SCTS) model. Under the constraint of a fixed chirp parameter, we observe an amplification in the impact of the chirp parameter on the laser field waveform as the wavelength increases. This enhancement facilitates effective modulation of the ionization time window. As the wavelength reaches a certain threshold, the double-slit interference pattern undergoes an observable expansion towards the left. Furthermore, based on the variations in X-axis momentum (Px) concerning ionization time at different wavelengths and the corresponding distribution of classical electron trajectories at those wavelengths, we present a more comprehensive explanation for the expansion of interference patterns. This expansion can be attributed to changes in wavelength, which result in modifications to the laser field’s waveform, consequently leading to a significant acceleration of ionized electrons when exposed to chirped laser pulses. It is worth noting that by tuning the negative chirp parameter, the leftward expansion of the double-slit interference pattern can also be achieved, particularly when shorter wavelengths of chirped laser pulses are employed.

How an emergent cosmology of a nonlocally unified, meaningfully in-formed and holographically manifested Universe can underpin and frame the biological embodiment of quantum entanglement

With a Nobel Prize for Physics widely viewed as only given for ‘settled’ science, the award then essentially accepts the validity of universal nonlocality. Other key discoveries and insights in recent years are also progressively pointing to the appearance of our Universe, its energy-matter and space-time, as not being foundational but emerging from deeper, discarnate realms of causation. as digitized and meaningful, in-formation, its manifestation pixelated at the so-named Planck scale of existence. Extending from studies of black holes to the entire Universe, a growing number of cosmologists have also developed the so-named holographic principle, to model the four-dimensional appearance of our Universe (three dimensions of space and one of time) as a holographic projection of its two- dimensional boundary. In framing the emergent cosmology of a nonlocally unified, meaningfully in-formed and holographically manifested Universe, an expansion of the three universal Laws of Thermodynamics to three Laws of Information, or Infodynamics also points the way to reconciling Quantum Theory that describes energy-matter and Relativity Theory that describes space-time and offers too an understanding of how the lifecycle of our Universe flows from its first moment until its last. Treating gravity as an emergent consequence of the in-formational and holographic structure of space- time and describing it as the consequence of the intropy associated with the positions in space-time of massive bodies, also points to the findings of the loss of phenotype identity in zero gravity and the role between gravity and cellular identity and the emergence of symbiogenesis.

Holographic Recording of Unslanted Volume Transmission Gratings in Acrylamide/Propargyl Acrylate Hydrogel Layers: Towards Nucleic Acids Biosensing.

The role of volume hydrogel holographic gratings as optical transducers in sensor devices for point-of-care applications is increasing due to their ability to be functionalized for achieving enhanced selectivity. The first step in the development of these transducers is the optimization of the holographic recording process. The optimization aims at achieving gratings with reproducible diffraction efficiency, which remains stable after reiterative washings, typically required when working with analytes of a biological nature or several step tests. The recording process of volume phase transmission gratings within Acrylamide/Propargyl Acrylate hydrogel layers reported in this work was successfully performed, and the obtained diffraction gratings were optically characterized. Unslanted volume transmission gratings were recorded in the hydrogel layers diffraction efficiencies; up to 80% were achieved. Additionally, the recorded gratings demonstrated stability in water after multiple washing steps. The hydrogels, after functionalization with oligonucleotide probes, yields a specific hybridization response, recognizing the complementary strand as demonstrated by fluorescence. Analyte-sensitive hydrogel layers with holographic structures are a promising candidate for the next generation of in vitro diagnostic tests.

APPROXIMATIONS OF THE THEORIES OF STRUCTURES WITH ONE EQUIVALENCE RELATION

Recently, various methods similar to the “transfer principle” have been rapidly developing, where one property of a structure or pieces of this structure is satisfied in all infinite structures or in another algebraic structure. Such methods include smoothly approximable structures, holographic structures, almost sure theories, and pseudofinite structures approximable by finite structures. Pseudofinite structures are mathematical structures that resemble finite structures but are not actually finite. They are important in various areas of mathematics, including model theory and algebraic geometry. Pseudofinite structures are a fascinating area of mathematical logic that bridge the gap between finite and infinite structures. They allow studying infinite structures in ways that resemble finite structures, and they provide a connection to various other concepts in model theory. Further studying pseudofinite structures will continue to reveal new insights and applications in mathematics and beyond. Pseudofinite theory is a branch of mathematical logic that studies structures that are similar in some ways to finite structures, but can be infinitely large in other ways. It is an area of research that lies at the intersection of model theory and number theory and deals with infinite structures that share some properties with finite structures, such as having only finitely many elements up to isomorphism. A. Lachlan introduced the concept of smoothly approximable structures in order to change the direction of analysis from finite to infinite, that is, to classify large finite structures that seem to be smooth approximations to an infinite limit. The theory of pseudofinite structures is particularly relevant for studying equivalence relations. In this paper, we study the model-theoretic property of the theory of equivalence relations, in particular, the property of smooth approximability. Let L = {E}, where Е is an equivalence relation. We prove that an any ω-categorical L-structure M is smoothly approximable. We also prove that any infinite L-structure M is pseudofinite.

Holographic Fabrication of 3D Moiré Photonic Crystals Using Circularly Polarized Laser Beams and a Spatial Light Modulator.

A moiré photonic crystal is an optical analog of twisted graphene. A 3D moiré photonic crystal is a new nano-/microstructure that is distinguished from bilayer twisted photonic crystals. Holographic fabrication of a 3D moiré photonic crystal is very difficult due to the coexistence of the bright and dark regions, where the exposure threshold is suitable for one region but not for the other. In this paper, we study the holographic fabrication of 3D moiré photonic crystals using an integrated system of a single reflective optical element (ROE) and a spatial light modulator (SLM) where nine beams (four inner beams + four outer beams + central beam) are overlapped. By modifying the phase and amplitude of the interfering beams, the interference patterns of 3D moiré photonic crystals are systemically simulated and compared with the holographic structures to gain a comprehensive understanding of SLM-based holographic fabrication. We report the holographic fabrication of phase and beam intensity ratio-dependent 3D moiré photonic crystals and their structural characterization. Superlattices modulated in the z-direction of 3D moiré photonic crystals have been discovered. This comprehensive study provides guidance for future pixel-by-pixel phase engineering in SLM for complex holographic structures.

Spin-orbit optical Hall effect in π-vector fields.

Given the tremendous increase of data in digital era, vector vortex light with strongly coupled spin and orbital angular momenta of photons have attracted great attention for high-capacity optical applications. To fully utilize such rich degrees of freedom of light, it is highly anticipated to separate the coupled angular momentum with a simple but powerful method, and the optical Hall effect becomes a promising scheme. Recently, the spin-orbit optical Hall effect has been proposed in terms of general vector vortex light using two anisotropic crystals. However, angular momentum separation for π-vector vortex modes, another important part in vector optical fields, have not been explored and it remains challenging to realize broadband response. Here, the wavelength-independent spin-orbit optical Hall effect in π-vector fields has been analyzed based on Jones matrices and verified experimentally using a single-layer liquid-crystalline film with designed holographic structures. Every π-vector vortex mode can be decoupled into spin and orbital components with equal magnitude but opposite signs. Our work could enrich the fields of high-dimensional optics.

Optical trapping with holographically structured light for single-cell studies.

A groundbreaking work in 1970 by Arthur Ashkin paved the way for developing various optical trapping techniques. Optical tweezers have become an established method for the manipulation of biological objects, due to their noninvasiveness and precise controllability. Recent innovations are accelerating and now enable single-cell manipulation through holographic light structuring. In this review, we provide an overview of recent advances in optical tweezer techniques for studies at the individual cell level. Our review focuses on holographic optical tweezers that utilize active spatial light modulators to noninvasively manipulate live cells. The versatility of the technology has led to valuable integrations with microscopy, microfluidics, and biotechnological techniques for various single-cell studies. We aim to recapitulate the basic principles of holographic optical tweezers, highlight trends in their biophysical applications, and discuss challenges and future prospects.

Versatile generation and manipulation of phase-structured light beams using on-chip subwavelength holographic surface gratings

Abstract Phase-structured light beams carrying orbital angular momentum (OAM) have a wide range of applications ranging from particle trapping to optical communication. Many techniques exist to generate and manipulate such beams but most suffer from bulky configurations. In contrast, silicon photonics enables the integration of various functional components on a monolithic platform, providing a way to miniaturize optical systems to chip level. Here, we propose a series of on-chip subwavelength holographic waveguide structures that can convert the in-plane guided modes into desired wavefronts and realize complex free-space functions, including the generation of complex phase-structured light beams, arbitrarily directed vortex beam emission and vortex beam focusing. We use a holographic approach to design subwavelength holographic surface gratings, and demonstrate broadband generation of Laguerre–Gaussian (LG) and linearly polarized (LP) modes. Moreover, by assigning appropriate geometric phase profiles to the spiral phase distribution, the off-chip vortex beam manipulation including arbitrarily directed emission and beam focusing scenarios can be realized. In the experiment, directed vortex beam emission is realized by using a fabricated tilt subwavelength holographic fork grating. The proposed waveguide structures enrich the functionalities of dielectric meta-waveguide structures, which can find potential applications in optical communication, optical trapping, nonlinear interaction and imaging.

Transmission functions of transmissive multilayer inhomogeneous holographic photopolymer liquid crystal diffraction structures

A new analytical model of diffraction of quasimonochromatic light beams on spatially inhomogeneous multilayer diffraction structures formed in photopolymer material with nematic liquid crystals having smooth optical inhomogeneity in the thickness of layers is presented. It is shown that when an applied electric field isapplied to diffraction layers containing a photopolymer composition with a high proportion of liquid crystalline component, a transformation of the selective response with a significant shift in angular selectivity occurs

Top-Performance Transmission Gratings with Haloalkanes-Based Polymeric Composite Materials.

We report on highly transparent holographic phase transmission volume gratings recorded in the visible region at λ = 532 nm. The maximum measured diffraction efficiency is higher than 80% with a grating pitch of Λ≈ 300 nm and a refractive index modulation Δn ≈ 0.018. To obtain these results, we used a holographic mixture based on multi-reticulated acrylate and haloalkanes (1-bromo-butane and 1-bromo-hexane) and a synergic combination of camphore-quinone, which has a maximum absorbance at c.a. 470 nm, and R6G, here used as co-initiator, to efficiently initiate the photo-polymerization process. High transparent and high efficient holographic structures based on polymers can find applications in many research fields including integrated optics, sensors, high density data storage and security.

Nanostructured Luminescent Gratings for Sensorics.

Two-dimensional holographic structures based on photopolymer compositions with luminescent nanoparticles, such as quantum dots, are promising candidates for multiresponsive luminescence sensors. However, their applicability may suffer from the incompatibility of the components, and hence aggregation of the nanoparticles. We showed that the replacement of an organic shell at the CdSe/ZnS quantum dots' surface with monomer molecules of the photopolymerizable medium achieved full compatibility with the surrounding medium. The effect was demonstrated by luminescence spectroscopy, and steady-state and time-resolved luminescent laser scanning microscopy. We observed the complete spectral independence of local photoluminescence decay, thus proving the absence of even nanoscale aggregation, either in the liquid composition or in the nodes and antinodes of the grating. Therefore, nanostructured luminescent photopolymer gratings with monomer-covered quantum dots can act as hybrid diffractive-luminescent sensor elements.

A Frame Theory of Energetic Life: A Twisting Energy Solidified on the Holographic Fractal Structure

Life, as the most mysterious and unique phenomenon on the Earth, has confused humans since time began. Why does life exist as it does and how has the diversity of life developed? We, herein, propose a new theory of energetic life, based on existing energy laws, to interpret the evolution and categorization of physical life forms, from microscopic life to macroscopic life. According to this theory, life is a process in which a mass of energy flows and diffuses in the environment. This energy takes DNA as the three-dimensional blueprint, protein as the basic material unit, and fractal network structure as the framework, so as to solidify from energy and form a semi-solid structure. DNA base pairs simultaneously have dual properties as protein pointers and spatial coordinates, and the multi-level self-similar fractal helix structure ultimately guides the formation of different levels of the fractal structure of organisms. This theory organically links the life phenomenon from microscopic to macroscopic levels, from gene, cell and organ to organism, and it provides a new perspective on life, which may inspire biologists to better reveal the mystery of life.

Precise control of the ionization channel in strong-field ionization by a few-cycle chirped laser pulse

We investigate theoretically the photoelectron holography in strong-field ionization by a few-cycle chirped laser pulse. It is shown that the numerical results by solving the two-dimensional (2D) time-dependent Schr\"odinger equation (TDSE) are in agreement with that by using the semiclassical two-step (SCTS) model. The opening and the closing of the ionization channel can be controlled precisely by a few-cycle chirped laser pulse and the holographic interference structure can be isolated by adjusting the chirp parameters. This holographic interference structure is related to the rescattered electron wave packet (EWP) which released within an attosecond timescale. We demonstrate that the chirped laser pulse can be used to coherently control the recollision process. By analyzing the rescattered trajectory, we illustrate that the travel time of the rescattered electron is increased and the rescattered electron can obtain high return energy in a negatively chirped laser pulse. In addition, we also illustrate that the photoelectron momentum distributions (PMDs) are very sensitive to the carrier-envelope phase.

Exploring symmetries in photoelectron holography with two-color linearly polarized fields

We investigate photoelectron holography in bichromatic linearly polarized fields of commensurate frequencies rω and sω, with emphasis on the existing symmetries and for which values of the relative phase between the two driving waves they are kept or broken. Using group-theoretical methods, we show that, additionally to the well-known half-cycle symmetry, which is broken for r + s odd, there are reflection symmetries around the field zero crossings and maxima, which may or may not be kept, depending on how both waves are dephased. The three symmetries are always present for monochromatic fields, while for bichromatic fields this is not guaranteed, even if r + s is even and the half-cycle symmetry is retained. Breaking the half-cycle symmetry automatically breaks one of the other two, while, if the half-cycle symmetry is retained, the other two symmetries are either both kept or broken. We analyze how these features affect the ionization times and saddle-point equations for different bichromatic fields. We also provide general expressions for the relative phases ϕ which retain specific symmetries. As an application, we compute photoelectron momentum distributions for ω − 2ω fields with the Coulomb quantum orbit strong-field approximation and assess how holographic structures such as the fan, the spider and interference carpets behave, focusing on the reflection symmetries. The features encountered can be traced back to the field gradient and amplitude affecting ionization probabilities and quantum interference in different momentum regions.

Studying the process of holographic formation of multilayer inhomogeneous PPM-LC diffraction structures

The article describes a theoretical model for the formation of a multilayer diffractive holographic structure (MIHDS) based on a photopolymer composition including liquid crystals (LC). We presented mathematical modeling of spatial profiles kinetics of the refractive index of the first harmonic of MIHDS considering the photoinduced light absorption (PLA) of the non-optimized and optimized composition. Numerical modeling has shown that optimization of the composition of MIHDS at different thicknesses of the diffraction layer requires a difference in the concentration of the dye-sensitizer for subsequent layers.

Wavelength dependence of photoelectron momentum distributions in a spatially inhomogeneous field

The effect of the spatial inhomogeneity on the photoelectron momentum distributions (PMDs) is recently identified [Chen et al., Phys. Rev. A 104, 043107 (2021)]. As an important parameter of the laser field, the wavelength cannot be ignored. We theoretically investigate the wavelength dependence of the PMDs in a spatially inhomogeneous field. The results show that the PMDs gradually move to the negative direction with the increase of the laser wavelength compared with the case of the spatially homogeneous field. However, a critical value of the wavelength appears, where the PMDs are just separated. Then, the PMDs can be clearly separated into two regions and the rescattering energy of the electron is tremendously enhanced. We illustrate that the holographic interference structure can be isolated in the relative high-energy region and the holographic interference structure for the shorter wavelength is more obvious. A prominent high-energy peak appears in the critical wavelength and the high-energy peak is sensitive to the initial transverse momentum of the rescattering electrons after tunneling. Moreover, we also demonstrate that the critical wavelength will change with the inhomogeneity parameters.

Arbitrary amplitude and phase control in visible by dielectric metasurface.

Metasurfaces have been widely studied for arbitrary manipulation of the amplitude, phase and polarization of a field at the sub-wavelength scale. However, realizing a high efficiency metasurface with simultaneous and independent control of the amplitude and phase in visible remains a challenge. In this work, an ultrathin single-cell dielectric metasurface which can modulate arbitrary complex amplitude in transmission mode is proposed. The amplitude is controlled by adjusting the dipoles and quadrupoles by tuning the geometric size, while the phase is manipulated based on the Pancharatnam-Berry phase by rotating the meta-atom. Complex amplitude fields for generating holographic images and structure light are utilized to verify the reliability of the proposed structure. It has been experimentally demonstrated that the quality of holographic image of complex-amplitude hologram encoded on the proposed metasurface is better than that of phase-only holograms and verified by simulation that complex structure light can be generated by the proposed structure. Our work expands the superior limits of various applications, including arbitrary beam shaping, 3D biological imaging, optical computing, and optics-on-chip devices.

Identifying the complexity of the holographic structures in strong field ionization

We present numerical investigations of the strong-field attosecond photoelectron holography by analyzing the holographic interference structures in the two-dimensional photoelectron momentum distribution (PMD) in hydrogen atom target induced by a strong infrared laser pulse. The PMDs are calculated by solving the full-dimensional time-dependent Schrödinger equation. The effect of the number of optical cycles on the PMD is considered and analyzed. We show how the complex interference patterns are formed from a single-cycle pulse to multi-cycle pulses. Furthermore, snapshots of the PMD during the time evolution are presented for a single-cycle pulse in order to track the formation of the so-called fish-bone like holographic structure. The spider- and fan-like holographic structures are also identified and investigated. We found that the fan-like structure could only be identified clearly for pulses with three or more optical cycles and its symmetry depends closely on the number of optical cycles. In addition, we found that the intensity and wavelength of the laser pulse affect the density of interference fringes in the holographic patterns. We show that the longer the wavelength, the more the holographic structures are confined to the polarization axis.