Light Modulator Research Articles

Manipulating the light spectrum to increase the biomass production, physiological plasticity and nutritional quality of Eruca sativa L

The extensive development in light-emitting diodes (LEDs) in recent years provides an opportunity to positively influence plant growth and biomass accumulation and to optimize biochemical composition and nutritional quality. This study aimed to assess how different light spectra affect the growth, photosynthesis and biochemical properties of Eruca sativa. Therefore two LED lighting modes - red:blue (RB, 1:1) and red:green:blue (RGB, 2:1:2) were compared to the conventional white light fluorescent tubes (WL). Plant biomass, photosynthetic performance, several antioxidants, polyamines and nitrates contents were analyzed across different treatments. The plant growth was affected by the light quality - the presence of green light in the spectrum resulted in smaller plants and leaves, and correspondingly less biomass. RB spectral mode enhanced the total antioxidant and guaiacol peroxidase activity, pigments, flavonoids, polyphenols, ascorbate and polyamines contents. This effect under RB was combined with better leaf development compared to RGB and less nitrate in the leaves among all treatments. The RB light generated modifications in polyamines, which are interrelated with the nitrate content, further induce important metabolite and antioxidant changes. Both RB and RGB enhanced photosynthesis. The afterglow thermoluminescence band varied according to leaves development, being higher in RB and WL as a consequence of their faster growth. The RB light spectrum was found to be the most efficient for promoting the growth, biochemical composition, and overall quality of Eruca sativa compared to RGB and WL. These findings suggest that RB LEDs can be an effective tool for improving crop production in controlled environments.

Shape sensing endoscope fiber

Minimally invasive and robotic surgeries are growing areas that benefit patients through reduced recovery time. Medical fiber optics play an important role in these procedures by enabling instrument navigation, imaging, sensing, power delivery, and diagnostics in a small form factor. One route to further miniaturization is to combine these functions, or a subset of these functions, into a single strand of optical fiber. In this work, we present a fiber and fan-in device that enables shape sensing, imaging, power delivery, and potentially additional sensing capabilities, such as temperature and/or pressure, in the same waveguide. The refractive index profile of the multimode waveguide in our fiber is similar to step index fibers used in laser delivery and is suitable for imaging applications; however, it also contains seven single mode cores twisted in a helix and with quasi-continuous Bragg gratings along their entire length, such as are used in fiber shape sensing. We first calibrate the transmission matrix of the multimode waveguide to enable the formation of a focused spot at the distal end of the fiber with a spatial light modulator. A second calibration allows us to reconstruct the shape of the fiber using optical frequency domain reflectometry in the twisted shape sensing cores. We show that these multiple functions can be performed simultaneously with our device and that changes in the curvature of the fiber correlate with the quality of the distal spot produced through the fiber, which is an important step towards maintaining the imaging calibration as the fiber is manipulated.

Random Raman Lasing in Diode-Pumped Multi-Mode Graded-Index Fiber with Femtosecond Laser-Inscribed Random Refractive Index Structures of Various Shapes

Diode-pumped multi-mode graded-index (GRIN) fiber Raman lasers provide prominent brightness enhancement both in linear and half-open cavities with random distributed feedback via natural Rayleigh backscattering. Femtosecond laser-inscribed random refractive index structures allow for the sufficient reduction in the Raman threshold by means of Rayleigh backscattering signal enhancement by +50 + 66 dB relative to the intrinsic fiber level. At the same time, they offer an opportunity to generate Stokes beams with a shape close to fundamental transverse mode (LP01), as well as to select higher-order modes such as LP11 with a near-1D longitudinal random structure shifted off the fiber axis. Further development of the inscription technology includes the fabrication of 3D ring-shaped random structures using a spatial light modulator (SLM) in a 100/140 μm GRIN multi-mode fiber. This allows for the generation of a multi-mode diode-pumped GRIN fiber random Raman laser at 976 nm with a ring-shaped output beam at a relatively low pumping threshold (~160 W), demonstrated for the first time to our knowledge.

Influence of multi-stress factors on the growth of Chlorella pyrenoidosa and Scenedesmus abundans using response surface methodology.

This study evaluated the biofuel production potential of two algal species, Chlorella pyrenoidosa and Scenedesmus abundans, under stress conditions induced by nutrient supplementation or starvation at varying light intensities. Central composite face-centered design response surface methodology (CCFD-RSM) was employed to optimize stress conditions by varying the sodium nitrate (NaNO3), potassium dihydrogen phosphate (KH2PO4), dipotassium hydrogen phosphate (K2HPO4), cultivation time, and light intensity. The study included both C. pyrenoidosa and S. abundans, which presented increased biomass yields when subjected to nutrient starvation. Under the optimized conditions, the dry biomass yield was 98.26mg/L for C. pyrenoidosa and 110mg/L for S. abundans. Lipid yields were approximately 22.47% for C. pyrenoidosa and 29.06% for S. abundans under these optimized growth conditions. The optimized parameters for maximum biomass and lipid production were identified as C. pyrenoidosa, and the optimized conditions required 0.805g/L NaNO3, 0.052g/L K2HPO4, 0.099g/L KH2PO4, 17days of culture, and 5168.39lx of light intensity. For S. abundans, the optimal conditions were 1.065g/L NaNO3, 0.071g/L K2HPO4, 0.058g/L KH2PO4, 22days of cultivation, and 2897lx of light intensity. Overall, both C. pyrenoidosa and S. abundans have emerged as promising candidates for sustainable biodiesel production, highlighting their potential under stress conditions induced by nutrient modulation and variable light intensities.

Carbazole-Based Dual-Band Electrochromic Polymers: The Effect of Linkage Sites on Electrochromic Performance.

Dual-band electrochromic (EC) materials are expected to be utilized as building materials for energy saving, but their cycle stability is still an obstacle. Here, two D-A conjugated polymers, PDPPCz36 and PDPPCz27, based on diketopyrrolopyrrole and carbazole linked with different sites, are synthesized. Both of them exhibit dual-band EC behaviors with a dark blue color in the neutral state and high absorption in the near-infrared (NIR) region when oxidized. However, PDPPCz36 exhibits better cycle stability and a shorter response time than PDPPCz27. In the visible (VIS) region, the PDPPCz36 film exhibits an initial light modulation range (ΔT) of 43.0% and that of the PDPPCz27 film is 41.3%. After 100 cycles of redox, the ΔT of the PDPPCz36 film declines by 32%, while that of PDPPCz27 attenuates by more than 50%. A similar tendency is evident in the NIR region. Moreover, PDPPCz36 shows subsecond colored switch times both in the VIS (0.4 s) and NIR (0.7 s) regions, while those of PDPPCz27 are 2.1 and 1.6 s, respectively. Further research suggests that 3,6-linked carbazoles in PDPPCz36 simultaneously inhibit the side reaction and film aggregation, which leads to better redox stability and shorter response time in both EC tests and devices.

Naked-eye light field display technology based on mini/micro light emitting diode panels: a systematic review and meta-analysis

The light field display technology based on panel light modulation has obvious industrial advantages. However, light field displays still causes discomfort for users in practical applications, due to issues such as angle of view, number of viewpoints, and crosstalk, etc. As a new type of high performance 2D display technology, mini/micro light emitting diode (MLED) has the potential to provide higher quality 3D display effects, but it may also bring new technological challenges. This paper provides a detailed investigation of technical principles and the latest research progress in light field display technology based on panel light modulation, and analyzes the industrial and academic research difficulties, which are brought about by the combination of MLED and naked-eye light field display. This paper is the first to complete a technical review specifically focused on MLED and naked-eye light field display, which is expected to accelerate the technological development and application process of naked-eye light field display based on MLED panels.

Harnessing physics-guided neural networks for tailoring the orbital angular momentum spectrum in second harmonic generation

The management of orbital angular momentum (OAM) in frequency conversion processes is essential for numerous applications such as quantum and classical optical communications. This paper presents a wavefront modulation approach for the fundamental beam in second harmonic generation (SHG) to efficiently control the OAM spectrum. We employ an inverse design method to derive the necessary wavefront shape of the fundamental beam for achieving a desired SHG OAM spectrum. Specifically, we introduce an efficient inverse design technique based on physics-guided neural networks (PGNNs) that incorporates the coupled equations governing SHG, aimed at tailoring the OAM spectrum of SHG. Utilizing the proposed PGNN, we design the phase pattern for a spatial light modulator (SLM) to shape the wavefront of the fundamental beam. Furthermore, we present a novel loss function, to our knowledge, that effectively links the OAM of the SHG spectrum and efficiency to the SLM phase pattern and crystal temperature, independent of empirical weight coefficients. The proposed PGNN facilitates the purification of the SHG OAM spectrum, even when the fundamental beam comprises mixed Laguerre–Gaussian (LG) modes. Additionally, we demonstrate the generation of desired SHG spectra using the proposed PGNN framework. This study introduces what we believe to be a groundbreaking inverse design method for developing photonic devices with customized functionalities, addressing challenges associated with traditional data-driven deep learning techniques.

Two-mode subharmonic generating system with coherent and thermal light

The statistical and squeezing characteristics of the light generated by a two-mode subharmonic generating system in a cavity pumped by two-mode coherent light and coupled to a two-mode thermal reservoir through a single-port mirror have been studied in this study. We construct the c-number Langevin equations linked to the normal ordering using the master equation for the system under discussion, and we establish the correlation characteristics of the noise forces. The mean and variance of the photon number of the cavity light are then determined using the solutions of the resulting differential equations. We have discovered that the cavity light mode’s photon statistics are super-Poissonian because the variance of the photon number is more significant than the mean of the photon number. Additionally, using the same solutions, we were able to extract the antinormally ordered characteristic function, which is used to calculate the Q function. In addition, the photon number distribution for the cavity mode is computed using the Q function. The variance of the plus and minus quadrature of the two-mode cavity light generated by the two-mode subharmonic generating system is also obtained. It is discovered that the cavity mode’s squeezing characteristics are unaffected by the two-mode driving coherent light, however, the thermal light has the effect of decreasing the squeezing of the cavity light and the squeezing takes place in the plus quadrature. Finally, we discovered that when the cavity is coupled to a vacuum reservoir, there is a 50%\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\%$$\\end{document} maximum squeezing of the two-mode cavity at a steady state and at the threshold. The nondegenerate subharmonic generator generates a two-mode cavity light that is 50%\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\%$$\\end{document} entangled.

Complex-valued scatter compensation in nonlinear microscopy

Nonlinear, i.e., multiphoton microscopy is a powerful technique for imaging deep into biological tissues. Its penetration depth can be increased further using adaptive optics. In this work, we present a fast, feedback-based adaptive-optics algorithm, termed C-DASH, for multiphoton imaging through multiple-scattering media. C-DASH utilizes complex-valued light shaping (i.e., joint shaping of amplitude and phase), which offers several advantages over phase-only techniques: it converges faster, it delivers higher image quality enhancement, it shows a robust performance largely insensitive to the axial position of the correction plane, and it has a higher ability to cope with, on the one hand, scattering media that vary over time and, on the other hand, scattering media that are partially absorbing. Furthermore, our method is practically self-aligning. We also present a simple way to implement C-DASH using a single reflection off a phase-only spatial light modulator. We provide a thorough characterization of our method, presenting results of numerical simulations as well as two-photon excited fluorescence imaging experiments. Published by the American Physical Society 2024

High-dimensional quantum key distribution using orbital angular momentum of single photons from a colloidal quantum dot at room temperature

High-dimensional quantum key distribution (HDQKD) is a promising avenue to address the inherent limitations of basic quantum key distribution (QKD) protocols. However, experimental realizations of HDQKD to date have relied on indeterministic photon sources that limit the achievable key rate. In this paper, we demonstrate a full emulation of a HDQKD system using a single colloidal giant quantum dot (gQD) as a deterministic, compact, and room-temperature single-photon source (SPS). We demonstrate a practical protocol by encoding information in a high-dimensional space (d = 3) of the orbital angular momentum of the photons. Our experimental configuration incorporates two spatial light modulators for encoding and decoding the spatial information carried by individual photons. Our experimental demonstration establishes the feasibility of utilizing high radiative quantum yield gQDs as practical SPSs for HDQKD. We also experimentally demonstrate surpassing the traditional d = 2 QKD capacity with comparable error rates, indicating a significant improvement in performance while maintaining reliability.

On the stability of the dislocation structure of speckle fields

The features of propagation in free space of light beams with a dislocation structure of the wavefront are considered. The stability to the influence of diffraction of small-scale dislocation systems providing spatial super-resolution is analyzed. Based on a comparison of the characteristics of various dislocation formations, a conclusion is made about the greatest structural stability of systems with special type screw dislocations. Such dislocations can be obtained by azimuthal rotation of edge dislocations characterized by a sharp phase jump of light oscillations along the singular line. The obtained results will find application in optimizing the characteristics of optical devices with ultra-high spatial resolution, as well as in developing software for the operation of spatial light modulators forming beams with a specified amplitude-phase profile.

A Review on Photoacoustic Spectroscopy Techniques for Gas Sensing.

The rapid growth of industry and the global drive for modernization have led to an increase in gas emissions, which present significant environmental and health risks. As a result, there is a growing need for precise and sensitive gas-monitoring technologies. This review delves into the progress made regarding photoacoustic gas sensors, with a specific focus on the vital components of acoustic cells and acoustic detectors. This review highlights photoacoustic spectroscopy (PAS) as an optical detection technique, lauding its high sensitivity, selectivity, and capability to detect a wide range of gaseous species. The principles of photoacoustic gas sensors are outlined, emphasizing the use of modulated light absorption to generate heat and subsequently detect gas pressure as acoustic pressure. Additionally, this review provides an overview of recent advancements in photoacoustic gas sensor components while also discussing the applications, challenges, and limitations of these sensors. It also includes a comparative analysis of photoacoustic gas sensors and other types of gas sensors, along with potential future research directions and opportunities. The main aim of this review is to advance the understanding and development of photoacoustic gas detection technology.

The Effect of Display Polarity on Reading Speed and Reading Error Among Young Adults

Objective: The widespread adoption of digital devices has surged, particularly since the coronavirus disease 2019 (COVID-19) pandemic. Nearly everyone now owns devices like laptops, tablets, or smartphones, offering options for light mode (positive polarity) and dark mode (negative polarity) to suit individual preferences. This study examines how display polarity affects reading performance among young adults. Material and Methods: Thirty participants engaged in a 15-minute reading task on a laptop with randomly assigned display polarities, followed by a 15-minute break before repeating the task. Results: Reading speed, measured in words per minute (wpm), differed significantly between polarities, with negative polarity yielding higher speeds (136.27±25.58 wpm) compared to positive polarity (128.42±19.98 wpm), Z=-2.355, p-value<0.05. However, no significant polarity-related differences were found in reading errors, including mispronunciation (p-value=0.193) or omission (p-value=0.113). Conclusion: Negative polarity displays enhanced reading performance by increasing reading speed; while reading errors remained unaffected.

Deep-learning-assisted optical communication with discretized state space of structured light

Abstract The rich structure of transverse spatial modes of structured light has facilitated their extensive applications in quantum information and optical communication. The Laguerre-Gaussian (LG) modes, which carry a well-defined orbital angular momentum (OAM), consist of a complete orthogonal basis describing the transverse spatial modes of light. The application of OAM in free-space optical communication is restricted due to the experimentally limited OAM numbers and the complex OAM recognition methods. Here, we present a novel method that uses the advanced deep learning technique for LG modes recognition. By discretizing the spatial modes of structured light, we turn the OAM state regression into classification. A proof-of-principle experiment is also performed, showing that our method effectively categorizes OAM states with small training samples and the accuracy exceeds 99% from 3-dimensional to 15-dimensional space. By assigning each category a classical information, we further apply our approach to an image transmission task, achieving a transmission accuracy of 99.58%, which demonstrates the ability to encode large data with low OAM number. This work opens up a new avenue for achieving high-capacity optical communication with low OAM number based on structured light.

An Aquatic Autonomic Nervous System.

Reproducing human nervous systems with endogenous mechanisms has attracted increasing attention, driven by its great potential in streamlining the neuro-electronic interfaces with bilateral signaling. Here, an artificial aquatic autonomic nervous system (ANS) with switchable excitatory/inhibitory characteristics and acetylcholine (ACh)-mediated plasticity is reported based on the newly emerged organic photoelectrochemical transistor (OPECT). Under the modulation of spatial light and ACh, the system exhibits an immediate switch between excitation and inhibition, and many pulse patterns as well as advanced ANS functions are mimicked. To demonstrate its potential usage, the artificial ANS is then utilized to control artificial pupils and muscles to emulate real biological responses during an emergency. In contrast to previous solid-state attempts, this ANS is aqueous compatible just like biological nervous systems, which are capable of real neurotransmitter mediation.

One-grating common-path phase-shifting interferometer for quantitative phase imaging

A one-grating common-path phase-shifting interferometer for quantitative phase imaging is proposed as an improvement over the original interferometer design. In the original version, the setup is long, involving a grating pair, and requires precise mechanical translation of the grating, which poses difficulties for practical applications. The proposed interferometer utilizes grating multiplexing to reduce the length of the optical setup and uses a phase-only spatial light modulator to implement pinhole filtering and phase shifting simultaneously without any moving parts, making it more conducive for the realization of a practical version.

Scaling of ultrashort-pulsed laser structuring processes for electromobility applications using a spatial light modulator

The structuring of lithium-ion battery (LIB) electrodes and the diffusion media (DM) for polymer electrolyte membrane fuel cells (PEMFCs) with ultrashort laser pulses enables improved performance characteristics of both technologies. However, the transfer of the approaches from a laboratory scale to a commercial use has previously been hindered by the low average output power of ultrashort-pulsed (USP) laser beam sources and the limited productivity of single-beam structuring using scanning optics. Recent advancements in the development of USP laser systems have led to a steady increase in the available output power, thereby enabling new fields of applications. This study aims at accelerating the USP laser structuring of LIB electrodes and DM for PEMFCs to industrially relevant processing rates by comparing a single-beam with a multibeam structuring process regarding ablation characteristics and quality. For the multibeam strategy, the shape of the laser beam was modified by a spatial light modulator (SLM). In addition to microholes, the insertion of microchannels was investigated to demonstrate the high flexibility of state-of-the-art SLMs. The geometry of the created structures was measured with a laser scanning microscope, and the different layers were tested for their geometrical and electrochemical properties to compare both technologies. The results confirmed that applying an SLM enables high-quality microstructures with significantly higher structuring rates. Furthermore, this contribution includes a theoretical analysis of the specifications required for a laser setup to reach an industrially relevant productivity of the structuring processes.

One molecule to couple them all: Toward realistic numbers of molecules in multiscale molecular dynamics simulations of exciton-polaritons.

Collective strong coupling of many molecules to the confined light modes of an optical resonator can influence the photochemistry of these molecules, but the origin of this effect is not yet fully understood. To provide atomistic insights, several approaches have been developed based on quantum chemistry or molecular dynamics methods. However, most of these methods rely on coupling a few molecules (or sometimes only one) to a single cavity mode. To reach the strong coupling regime with such a small number of molecules, much larger vacuum field strengths are employed than in experiments. To keep the vacuum field realistic and avoid potential artefacts, the number of coupled molecules should be significantly increased instead, but that is not always possible due to restrictions on computational hardware and software. To overcome this barrier and model the dynamics of an arbitrarily large ensemble of molecules coupled to realistic cavity fields in atomistic molecular dynamics simulations, we propose to coarse-grain subsets of molecules into one or more effective supermolecules with an enhanced dipole moment and concerted dynamics. To verify the validity of the proposed multiscale model, we performed simulations in which we investigated how the number of molecules that are coupled to the cavity affects excited-state intra-molecular proton transfer, polariton relaxation, and exciton transport.

Robust and efficient calibration method of liquid-crystal spatial light modulator based on the linear combination strategy

Abstract Phase-only spatial light modulators (SLMs) play a vital role in virous fields. However, its modulation accuracy is compromised by the static aberration and the phase response nonlinearity. To enhance the modulation accuracy, this paper presents an innovative full calibration method for SLMs, effectively addressing both static aberration and nonlinear phase responses using only two shots of camera. The main highlight of this paper is the binding of a novel linear combination strategy and a unique kinoform. This binding can eliminate phase distortion between two shots of camera, making our method dramatically robust in correcting phase response nonlinearity. Additionally, benefit from the accurate correction of phase response nonlinearity, the static aberration is accurately compensated by the single-shot spatial carrier phase-shifting technology. In conclusion, the proposed method's strong robustness, precision, and efficiency position it as an ideal solution for SLM calibration.

Ultrathin metasurface for super multi-view 3D display with linear and circular polarization control

Multiview 3D display technologies are advantageous due to their smooth motion parallax, visual discomfort alleviation, and wide depth of focus. However, the potential applications of this technology are constrained by its bulky size and limited light modulation capability. Metasurfaces offer diverse wavefront control by manipulating the phase, amplitude, and polarization of light. They provide design freedom and high image quality for multiview 3D display technologies. Here, we propose an ultrathin metasurface-based super multiview 3D display that can effectively modulate the flexibility of linearly polarized (LP) and circularly polarized (CP) electromagnetic waves. Numerical results demonstrate that it can produce 24 views together for LP and CP waves and high-quality reconstructed 3D images are obtained. The suggested metasurface for super multiview 3D display is promising to underpin the advancement of meta-optics-based operations in 3D display, imaging and integrated optics.