Control Of Light Fields Research Articles

On-demand spatial modes and vortex beams from a visible Pr:YLF orbital Poincaré laser with a hybrid pumping scheme

The controlled visible spatial modes and vortex beams with tunable properties are highly sought after in cutting-edge applications, such as optical communication. In this study, by utilizing a hybrid pumping scheme, we demonstrate an ultra-compact, 607 nm orbital Poincaré laser based on a diode-pumped Pr:YLF laser. The system can generate various structured modes, including Laguerre-Gaussian (LG), Hermite-Gaussian (HG), and Hermite-Laguerre-Gaussian (HLG), all of which are mapped onto a first-order orbital Poincaré sphere. A numerical analysis of the coherent superposition of HG modes with varying phases is in complete agreement with the experimental results. The handedness of the generated vortex beam can be selectively controlled by precisely adjusting the angle of output coupler. In comparison to other schemes, the hybrid pumping scheme offers advantages of high precision and excellent tunability, enabling the emitting of high-order HG modes, LG modes, along with a wide range of spatial modes on the orbital Poincaré sphere. Our scheme can also be extended to different gain media, which could lead to the creation of structured beams with richer wavelength, offering a promising platform for innovative studies on multidimensional light-field control.

Light Field Modulation Algorithms for Spatial Light Modulators: A Review

The coding method of spatial light modulator is the core key of spatial light field modulation technology, and the needs of the modulation algorithm are different under the specified mode and application requirements. This paper first reviews the progress made in recent years in light field control algorithms for digital micromirror devices (DMDs) and liquid crystal spatial light modulators (LC-SLM). Based on existing algorithms, the impact of optimization methods is analyzed. Then, the application areas of the different algorithms are summarized, and the characteristics of the control algorithms are analyzed. In addition, this review highlights innovative breakthroughs achieved by using various coding schemes and spatial light modulators (SLM) to manipulate the light field. Finally, critical future challenges facing emerging control algorithm technologies are outlined, while prospects for developing SLM control algorithms are proposed.

Enhancing the efficiency of high-order harmonics with two-color non-collinear wave mixing in silica

The emission of high-order harmonics from solids under intense laser-pulse irradiation is revolutionizing our understanding of strong-field solid-light interactions, while simultaneously opening avenues towards novel, all-solid, coherent, short-wavelength table-top sources with tailored emission profiles and nanoscale light-field control. To date, broadband spectra in solids have been generated well into the extreme-ultraviolet (XUV), but the comparatively low conversion efficiency in the XUV range achieved under optimal conditions still lags behind gas-based high-harmonic generation (HHG) sources. Here, we demonstrate that two-color high-order harmonic wave mixing in a fused silica solid is more efficient than solid HHG driven by a single color. This finding has significant implications for compact XUV sources where gas-based HHG is not feasible, as solid XUV wave mixing surpasses solid-HHG in performance. Moreover, our results enable utilizing solid high-order harmonic wave mixing as a probe of structure or material dynamics of the generating solid, which will enable reducing measurement times compared to the less efficient regular solid HHG. The emission intensity scaling that follows perturbative optical wave mixing, combined with the angular separation of the emitted frequencies, makes our approach a decisive step for all-solid coherent XUV sources and for studying light-engineered materials.

Femtosecond laser direct nanolithography of perovskite hydration for temporally programmable holograms

Modern nanofabrication technologies have propelled significant advancement of high-resolution and optically thin holograms. However, it remains a long-standing challenge to tune the complex hologram patterns at the nanoscale for temporal light field control. Here, we report femtosecond laser direct lithography of perovskites with nanoscale feature size and pixel-level temporal dynamics control for temporally programmable holograms. Specifically, under tightly focused laser irradiation, the organic molecules of layered perovskites (PEA)2PbI4 can be exfoliated with nanometric thickness precision and subwavelength lateral size. This creates inorganic lead halide capping nanostructures that retard perovskite hydration, enabling tunable hydration time constant. Leveraging advanced inverse design methods, temporal holograms in which multiple independent images are multiplexed with low cross talk are demonstrated. Furthermore, cascaded holograms are constructed to form temporally holographic neural networks with programmable optical inference functionality. Our work opens up new opportunities for tunable photonic devices with broad impacts on holography display and storage, high-dimensional optical encryption and artificial intelligence.

Joint optimization of coded aperture metasurface and residual self-attention network for snapshot full-Stokes imaging.

Traditional full-Stokes polarization imaging typically relies on the movements or segmentation of imaging systems, often accompanied by sacrifices in temporal or spatial resolution. Therefore, simultaneous encoding of full-Stokes vectors at the pixel scale is of great significance. Benefiting from the multi-dimensional light field control capability of metasurfaces, a coded aperture metasurface for polarization imaging is proposed in this paper, which can achieve pixel-level encoding of four Stokes vectors in a single imaging session. In addition, a Stokes residual self-attention network is designed to restore the encoded image, where the introduction of a channel-wise self-attention mechanism can effectively address the impact of intensity differences between Stokes vectors. Since the control of polarization states by metasurfaces is a differentiable physical process, the front-end metasurface encoding and back-end recovery network parameters can be jointly optimized, and this work achieves high-quality polarization imaging via such co-optimization methods. The proposed work demonstrates the flexibility and designability of metasurfaces in compact computational full-Stokes imaging systems.

Watt‐Level Second‐Order Topological Charge Ultrafast Green Vortex Laser with Quasi ‐2D PEA2(CsPbBr3)n‐1PbBr4 Perovskite Films Saturable Absorber

AbstractUltrafast vortex beams have significant scientific and practical value because of their unique phase properties in both the longitudinal and transverse modes, enabling multi‐dimensional quantum control of light fields. Directly generating watt‐level ultrafast vortex beams with large angular momentum has remained a major challenge due to the limitations of mode‐locked materials and existing spatiotemporal mode‐locking generation methods. In this study, quasi‐2D PEA2(CsPbBr3)n‐1PbBr4 perovskite films are prepared by an anti‐solvent method and employed for the first time in a mode‐locked resonator operating in free space. Utilizing the angle‐based non‐collinear pumping and frequency doubling techniques, the second‐order ultrafast green vortex beams with a power of up to 1.05 W and a duration of 373 ps are generated. Experimental findings demonstrate the strong nonlinear saturable absorption properties of quasi‐2D PEA2(CsPbBr3)n‐1PbBr4 perovskite films at high power levels, highlighting their considerable potential in ultrafast laser technology and nonlinear optics.

Local Light Field Control Enables Efficient Quantum Dot Color Conversion Films for Mini‐LED Backlit Displays

AbstractQuantum dot (QD) color conversion films (QD‐CCFs) are used in ultrahigh definition (UHD) Mini‐LED backlit displays due to their narrow band emission and high color purity. However, their poor light conversion efficiency (LCE) leads to greater film thickness and thus high cost. Herein, this study proposes a local light field control strategy to enhance the LCE of QD‐CCFs using high‐refractive BN nanosheets. The LCEs of the green and red QD‐CCFs can increase from 29.9% and 34.8% to 67.4% and 91.0% after adding BN nanosheets, respectively. Combining the experimental data with the finite‐difference time domain (FDTD) simulations, the enhanced LCEs can be attributed to observably increased blue light absorption and improved light extraction efficiency of the light emitted from QDs. The white Mini‐LEDs, prepared by integrating the optimized QD‐CCFs containing BN nanosheets with blue Mini‐LED chips, show a high luminous efficiency of 70.2 lm W−1, a high external quantum efficiency of 36.2%, and a wide color gamut of 96.3% Rec. 2020 standards. This work provides an interesting idea for designing high‐efficiency QD‐CCFs toward low‐cost UHD Mini‐LED backlit displays.

Broadband wavelength designable achromatic grating based on a cholesteric liquid crystal template

Liquid crystal (LC) gratings have played important roles in light field control due to the advantages of being lightweight, low cost, having no moving parts, and low power consumption. However, the chromatic aberration limits the bandwidth of the LC device and affects the efficiency of the grating. To solve the chromatic aberration issue, a broadband wavelength designable achromatic grating is proposed. Different grating structures are integrated into a single-layer templated cholesteric liquid crystal (CLC) device, and the achromatic diffraction wavelength of the grating can be freely designed from the visible spectral region to the infrared range within the Bragg reflection band of the CLCs. The diffraction intensity of different orders can be changed with the electric field applied to meet the need for dynamic modulation. This grating shows suitable potential applications in optical communication and displays.

Plasmonic nanosensor and pressure-induced transparency based on coupled resonator in a nanoscale system.

Plasmonic nanosensors and the dynamic control of light fields are of the utmost significance in the field of micro- and nano-optics. Here, our study successfully demonstrates a plasmonic nanosensor in a compact coupled resonator system and obtains the pressure-induced transparency phenomenon for the first time to our knowledge. The proposed structure consists of a groove and slot cavity coupled in the metal-insulator-metal waveguide, whose mechanical and optical characteristics are investigated in detail using the finite element method. Simulation results show that we construct a quantitative relationship among the resonator deformation quantity, the applied pressure variation, and the resonant wavelength offset by combining the mechanical and optical properties of the proposed system. The physical features contribute to highly efficient plasmonic nanosensors for refractive index and optical pressure sensing with sensitivity of 1800 nm/RIU and 7.4 nm/MPa, respectively. Furthermore, the light waves are coupled to each other in the resonators, which are detuned due to the presence of pressure, resulting in the pressure-induced transparency phenomenon. It is noteworthy to emphasize that, unlike previously published works, our numerical results take structural deformation-induced changes in optical properties into account, making them trustworthy and practical. The proposed structure introduces a novel, to the best of our knowledge, approach for the dynamic control of light fields and has special properties that can be utilized for the realization of various integrated components.

Light field control and automatic identification experimental system for physical impairment of glass samples

In this paper, we firstly propose a novel identification method for physical impairment of glass spheres samples based on the light field control. An identification simulation subsystem based on the finite difference time domain (FDTD) method to numerically study the light field control is proposed. The numerical results are consistent with the experimental data. On the basis of above numerical investigation, an automaticidentification experimental system for physical impairment of glass samples based on the Cortex-M3 is proposed. The relevanthardware circuitdesign,main program design, subprogram design of circuit modules, system specific framework structure and corresponding component design,andmaininterface between the master computer and slave microcontroller are accomplished. An automaticidentification experimental system for physical impairment of glass samples with automatic feeding subsystem and automatic sorting subsystem is achieved.

Microsphere photolithography with dynamic angular spectra control for metasurface fabrication.

Microsphere photolithography (MPL) is a promising technique for cost-effective fabrication of large-scale metasurfaces. This approach generates an array of photonic jets by the collimated illumination of self-assembled microspheres. The photonic jets can be precisely steered within the unit cell defined by each microsphere by changing the angle of incidence. This allows for the creation of complex metasurface element geometries. Computer controlled articulation of the substrate relative to a static UV source allows the direct-write of different metasurface elements. However, this is time-consuming and requires registration between each exposure for complex features. This paper investigates a single exposure method with the dynamic continuous angle of incidence control provided by a Digital Micromirror Device (DMD) in the front Fourier plane of the projection system. The grayscale values of the DMD pixels can be adjusted to provide optical proximity correction. Larger patterns can be achieved by scanning the substrate relative to the exposure beam. This approach is demonstrated with the creation of hierarchical patterns. This work greatly simplifies the MPL exposure process for complex resonators and provides potential for full light field control.

Ultrafast Metaphotonics

The exploration of optical and photonic phenomena, particularly the modulation of pulse signals and the ultrafast control of light fields at extreme temporal and spatial scales, substantially enhances our understanding of light–matter interactions and broadens the scope of potential applications inspired by metamaterials and metasurfaces. In this perspective, we highlight advancements in ultrafast metaphotonics by introducing ultrafast pulse shaping and control using metadevices. We begin with a detailed exposition of the principles of metasurfaces and evaluate their role in manipulating light fields in high-frequency and terahertz bands, emphasizing the importance of metasurfaces in ultrafast optics. We then present several methods for controlling the output response of metadevices using external physical fields or phase-change materials to achieve active metadevices. Finally, we anticipate the prospects of this field in terms of fundamental research and practical applications. The integration of these 2 disciplines will drive vibrant developments across multiple fields, including biology, chemistry, and materials science.

Biochemical and Preclinical Evaluation with Synthesis and Docking Study of Pyridopyrimidines and Selenium Nanoparticle Drugs for Cancer Targeting

Abstract: The coding method of spatial light modulator is the core key of spatial light field modulation technology, and the needs of the modulation algorithm are different under the specified mode and application requirements. This paper first reviews the progress made in recent years in light field control algorithms for digital micromirror devices (DMDs) and liquid crystal spatial light modulators (LC-SLM). Based on existing algorithms, the impact of optimization methods is analyzed. Then, the application areas of the different algorithms are summarized, and the characteristics of the control algorithms are analyzed. In addition, this review highlights innovative breakthroughs achieved by using various coding schemes and spatial light modulators (SLM) to manipulate the light field. Finally, critical future challenges facing emerging control algorithm technologies are outlined, while prospects for developing SLM control algorithms are proposed.

Stimuli‐Responsive Active Materials for Dynamic Control of Light Field (2/2023)

Stimuli‐Responsive Active Materials for Dynamic Control of Light Field (2/2023)

Stimuli‐responsive active materials for dynamic control of light field

AbstractThe increasing demand for the multidimensional and dynamic control of light has spurred the development of stimuli‐responsive, reconfigurable, and programmable optical systems. Liquid crystals (LCs), which combine liquid‐like stimuli‐responsiveness and crystal‐like orientational ordering, have emerged as highly appealing soft materials. Owing to their exceptional optical performance and programmable functionalities, they are becoming incredibly important materials in active planar optics and photonics. Additionally, silk proteins, luminescent materials, and metasurfaces exhibit dynamic optical properties, enabling remarkable multifunctional applications. This review focuses on the advancements in stimuli‐responsive materials, including LCs, silk proteins, luminescent materials, and active metasurfaces as well as some of these materials paired with LCs. Their attractive tunable applications in optics and photonics, along with the great potential for the future development of active optical systems, are also emphasized.

All‐Dielectric Multichannel Terahertz Metasurface Empowering Independent Wavefront Manipulation

AbstractMetasurfaces have demonstrated unprecedented capabilities in modulating the polarization and phase of electromagnetic waves and formed an emerging field of research, driving the exploitation of versatile compact devices. In this work, one transmission‐mode, multichannel all‐silicon metasurface platform that can implement functionalities separately in two orthogonally polarized output fields under linearly polarized incidences is proposed, which can effectively promote the design flexibility. Specifically, a single metasurface can realize multiple independent target phase distributions carrying specific phase relationships, thus enabling different information processing in different linear polarization states. For proof‐of‐principle experimental exhibitions, a monolayer metasurface composed of silicon pillars is designed, fabricated, and characterized to demonstrate the ability of multi‐dimensional light field control, such as polarization‐switchable focusing beam. Moreover, the other designed metasurface can generate polarization‐switchable Bessel vortex beams under linearly polarized incidences, which also verifies the flexibility and practicality of such platform. This metasurface platform may lead to new optical components, involving multichannel singular beam generators, information encoders, and holographic encryption devices.

High-order femtosecond vortices up to the 30th order generated from a powerful mode-locked Hermite-Gaussian laser

Femtosecond vortex beams are of great scientific and practical interest because of their unique phase properties in both the longitudinal and transverse modes, enabling multi-dimensional quantum control of light fields. Until now, generating femtosecond vortex beams for applications that simultaneously require ultrashort pulse duration, high power, high vortex order, and a low cost and compact laser source has been very challenging due to the limitations of available generation methods. Here, we present a compact apparatus that generates powerful high-order femtosecond vortex pulses via astigmatic mode conversion from a mode-locked Hermite-Gaussian Yb:KGW laser oscillator in a hybrid scheme using both the translation-based off-axis pumping and the angle-based non-collinear pumping techniques. This hybrid scheme enables the generation of femtosecond vortices with a continuously tunable vortex order from the 1st up to the 30th order, which is the highest order obtained from any femtosecond vortex laser source based on a mode-locked oscillator. The average powers and pulse durations of all resulting vortex pulses are several hundred milliwatts and <650 fs, respectively. In particular, 424-fs 11th-order vortex pulses have been achieved with an average power of 1.6 W, several times more powerful than state-of-the-art oscillator-based femtosecond vortex sources.

Carrier-envelope phase on-chip scanner and control of laser beams

The carrier-envelope phase (CEP) is an important property of few-cycle laser pulses, allowing for light field control of electronic processes during laser-matter interactions. Thus, the measurement and control of CEP is essential for applications of few-cycle lasers. Currently, there is no robust method for measuring the non-trivial spatial CEP distribution of few-cycle laser pulses. Here, we demonstrate a compact on-chip, ambient-air, CEP scanning probe with 0.1 µm3 resolution based on optical driving of CEP-sensitive ultrafast currents in a metal−dielectric heterostructure. We successfully apply the probe to obtain a 3D map of spatial changes of CEP in the vicinity of an oscillator beam focus with pulses as weak as 1 nJ. We also demonstrate CEP control in the focal volume with a spatial light modulator so that arbitrary spatial CEP sculpting could be realized.

Electro-optic modulation using lithium niobate metasurfaces with topological corner state

Electro-optically (EO) tunable metasurfaces have received considerable attention owing to their capability for dynamic light field control. Here, we report an EO lithium niobate metasurface mediated by topological corner states. Such a supercell of metasurface is constructed by two kinds of finite-sized arrays possessing different topological properties via the generalized two-dimensional (2D) Su–Schrieffer–Heeger model. The generated narrow-linewidth resonance with high-quality factor and strong field localization are very suitable for EO modulation. The results reveal that the required driving external voltage to fully shift the resonance can be well below 15 V. Furthermore, the 0.46 rad of phase modulation is also demonstrated along with transmission intensity modulation. The results offer a fundamental path of potential for tunable displays, light detection, spatial light modulators, and Floquet topological metasurfaces.

P‐2.14: Metasurface Applications in AR Near‐eye Display Devices

Augmented reality technology is a new display technology that integrates virtual digital information with real physical information and has become an important research field in global information technology. Near‐eye display devices are an important part of augmented reality. At present, traditional optical devices are widely used in near‐eye equipment, but the optical performance of the equipment is limited and the volume is large, making it difficult to meet the market's needs for thinness and high performance. With the development of micro‐nano processing technology, metasurfaces composed of artificial sub‐wavelength scale units, which are both ultra‐thin and can regulate arbitrary light fields, will become a new idea for the development of new near‐eye display devices.In this review, we first introduce the basic working principle of metasurface, mainly the principle of light field control of metasurface, analyze the aberration of metasurface imaging, and then evaluate the corresponding image quality. Then, a variety of existing metasurface design schemes are reviewed, including the design of structural elements, the overall architecture distribution, the design method of the system, the algorithm used, and the performance index. Finally, the problems to be solved and the future development direction of the current metasurface‐based near‐eye display system are summarized. Metasurface is easy to integrate and has a high degree of design freedom, which is expected to replace traditional optical components. Augmented reality near‐eye display devices based on metasurface with a large field of view and an ultra‐thin profile will become an important development direction in the future.