Plastic Optics Research Articles

Electro-Optically Configurable Synaptic Transistors With Cluster-Induced Photoactive Dielectric Layer for Visual Simulation and Biomotor Stimuli.

The integration of visual simulation and biorehabilitation devices promises great applications for sustainable electronics, on-demand integration and neuroscience. However, achieving a multifunctional synergistic biomimetic system with tunable optoelectronic properties at the individual device level remains a challenge. Here, an electro-optically configurable transistor employing conjugated-polymer as semiconductor layer and an insulating polymer (poly(1,8-octanediol-co-citrate) (POC)) with clusterization-triggered photoactive properties as dielectric layer is shown. These devices realize adeptly transition from electrical to optical synapses, featuring multiwavelength and multilevel optical synaptic memory properties exceeding 3 bits. Utilizing enhanced optical memory, the images learning and memory function for visual simulation are achieved. Benefiting from rapid electrical response akin to biological muscle activation, increased actuation occurs under increased stimulus frequency of gate voltage. Additionally, the transistor on POC substrate can be effectively degraded in NaOH solution due to degradation of POC. Pioneeringly, the electro-optically configurability stems from light absorption and photoluminescence of the aggregation cluster in POC layer after 200°C annealing. The enhancement of optical synaptic plasticity and integration of motion-activation functions within a single device opens new avenues at the intersection of optoelectronics, synaptic computing, and bioengineering.

Imaging and characterization of optical emission from ex vivo tissue during conventional and UHDR PBS proton therapy

Objective. Imaging of optical photons emitted from tissue during radiotherapy is a promising technique for real-time visualization of treatment delivery, offering applications in dose verification, treatment monitoring, and retrospective treatment plan comparison. This research aims to explore the feasibility of intensified imaging of tissue luminescence during proton therapy (PT), under both conventional and ultra-high dose rate (UHDR) conditions. Approach. Conventional and UHDR pencil beam scanning (PBS) PT irradiation of fresh ex vivo porcine tissue and tissue-mimicking plastic phantom was imaged using intensified complementary metal-oxide-semiconductor(CMOS) cameras. The optical emission from tissue was characterized during conventional irradiation using both blue and red-sensitive intensifiers to ensure adequate spectral coverage. Spectral characterization was performed using bandpass filters between the lens and sensor. Imaging of conventional proton fields (240 MeV, 10 nA) was performed at 100 Hz frame rate, while UHDR PBS proton delivery (250 MeV, 99 nA) was recorded at 1 kHz frame rate. Dependence of optical emission yield on proton energy was studied using an optical tissue-mimicking plastic phantom and a range shifter. Finally, we demonstrated fast beam tracking capability of fast camera towards in vivo monitoring of FLASH PT. Main results. Under conventional treatment dose rates optical emission was imaged with single spot resolution. Spot profiles were found to agree with the treatment planning system calculation within >90% for all spectral bands and spot intensity was found to vary with spectral filtration. The resultant polychromatic emission presented a maximum intensity at 650 nm and decreasing signal at lower wavelengths, which is consistent with expected attenuation patterns of high fat and muscle tissue. For UHDR beam imaging, optical yield increased with higher proton energy. Imaging at 1 kHz allowed continuous monitoring of delivery during porcine tissue irradiation, with clear identification of individual dwell positions. The number of dwell positions matched the treatment plan in total and per row showing adequate temporal capability of iCMOS imaging. Significance. For the first time, this study characterizes optical emission from tissue during PT and demonstrates our capability of fast optical tracking of pencil proton beam on the tissue anatomy in both conventional and UHDR setting. Similar to the Cherenkov imaging in radiotherapy, this imaging modality could enable a seamless, independent validation of PT treatments.

Bio-Inspired Photosensory Artificial Synapse Based on Functionalized Tellurium Multiropes for Neuromorphic Computing.

Nanomaterials like graphene and transition metal dichalcogenides are being explored for developing artificial photosensory synapses with low-power optical plasticity and high retention time for practical nervous system implementation. However, few studies are conducted on Tellurium (Te)-based nanomaterials due to their direct and small bandgaps. This paper reports the superior photo-synaptic properties of covalently bonded Tellurium sulfur oxide (TeSOx) andTellurium selenium oxide (TeSeOx)nanomaterials, which are fabricated by incorporating S and Se atoms on the surface of Te multiropes using vapor deposition. Unlike pure Te multiropes, the TeSOx and TeSeOx multiropes exhibit controllable temporal dynamics under optical stimulation. For example, the TeSOx multirope-based transistor displays a photosensory synaptic response to UV light (λ = 365nm). Furthermore, the TeSeOx multirope-based transistor exhibits photosensory synaptic responses to UV-vis light (λ = 365, 565, and 660nm), reliable electrical performance, and a combination of both photodetector and optical artificial synaptic properties with a maximum responsivity of 1500 AW-1 to 365nm UV light. This result is among the highest reported for Te-heterostructure-based devices, enabling optical artificial synaptic applications with low voltage spikes (1V) and low light intensity (21 µW cm-2), potentially useful for optical neuromorphic computing.

Controlling the Optical Properties of Transparent Auxetic Liquid Crystal Elastomers.

Determining the tunability of the optical coefficients, order parameter, and transition temperatures in optically transparent auxetic liquid crystal elastomers (LCEs) is vital for applications, including impact-resistant glass laminates. Here, we report measurements of the refractive indices, order parameters, and transition temperatures in a family of acrylate-based LCEs in which the mesogenic content varies from ∼50 to ∼85%. Modifications in the precursor mixture allow the order parameter, ⟨P2⟩, of the LCE to be adjusted from 0.46 to 0.73. The extraordinary refractive index changes most significantly with composition, from ∼1.66 to ∼1.69, in moving from a low to high mesogenic content. We demonstrate that all LCE refractive indices decrease with increasing temperature, with temperature coefficients of ∼10-4 K-1, comparable to optical plastics. In these LCEs, the average refractive index and the refractive index anisotropy are tunable via both chemical composition and order parameter control; we report design rules for both.

Solvatochromic, solvent-assisted deformable, and self-reinforcing smart windows enabled by molecular reconfiguration

Smart materials in which transparency can be dynamically controlled have broad prospects in smart window applications. This study reports solvatochromic optical hybrid plastics designed using a carboxylated poly(methyl methacrylate) (PMAA)/poly(methyl methacrylate) (PMMA) molecular configuration for the development of self-reinforcing smart windows. The reversible transparency of this transparent plastic is 87.54 % (at 550 nm), which can be reduced to 1.69 % after water-assisted treatment and restored to 86.45 % after ethanol treatment, reversibly. Moreover, the toughness of PMMA/PMAA = 1:2 film is 0.59 ± 0.06 MJ m−3, 73.50 % higher than that of pure PMMA. The films also exhibit the capability of ethanol-assisted arbitrary deformation. This study offers a novel perspective on fabricating PMMA-based materials and their application in smart windows.

Stress analysis of a large diameter aspheric plastic lens in the variable temperature assisted injection molding process.

The technology known as precision injection molding (PIM) has shown great promise in the large-scale manufacturing of optical plastic lenses. The primary challenge with the PIM process is accurately predicting and reducing residual stress in optical plastic lenses. In this work, the finite element method (FEM) was used to analyze the residual stress distribution in plastic lenses. A three-dimensional model was created using COMSOL software to investigate how residual stress and temperature varied in optical plastic lenses during the packing and cooling stages. Based on the results, variable temperature assisted injection molding experiments were conducted. The results show that the average residual stress in the optical plastic lenses has decreased by 56%, while the minimum and maximum residual stress levels have decreased by 60% and 61%, respectively. Since this method does not require the extra heat treatment of the optical lenses, it offers considerable cost and efficiency benefits.

IGZO/WO3-x-Heterostructured Artificial Optoelectronic Synaptic Devices Mimicking Image Segmentation and Motion Capture.

Currently, artificial neural networks (ANNs) based on memristors are limited to recognizing static images of objects when simulating human visual system, preventing them from performing high-dimensional information perception, and achieving more complex biomimetic functions is subject to certain limitations. In this work, indium gallium zinc oxide (IGZO)/tungsten oxide (WO3-x)-heterostructured artificial optoelectronic synaptic devices mimicking image segmentation and motion capture exhibiting high-performance optoelectronic synaptic responses are proposed and demonstrated. Upon electrical and optical stimulations, the device shows a variety of fundamental and advanced electrical and optical synaptic plasticity. Most importantly, outstanding and repeatable linear synaptic weight changes are attained by the developed memristor. By taking advantage of the notable linear synaptic weight changes, ANNs have been constructed and successfully utilized to demonstrate two applications in the field of computer vision, including image segmentation and object tracking. The accuracy attained by the memristor-based ANNs is similar to that of the computer algorithms, while its power has been significantly reduced by 105 orders of magnitude. With successful emulations of the human brain reactions when observing objects, the demonstrated memristor and related ANNs can be effectively utilized in constructing artificial optoelectronic synaptic devices and show promising potential in emulating human visual perception.

Energy-Efficient ReS2-Based Optoelectronic Synapse for 3D Object Reconstruction and Recognition.

The neuromorphic vision system (NVS) equipped with optoelectronic synapses integrates perception, storage, and processing and is expected to address the issues of traditional machine vision. However, owing to their lack of stereo vision, existing NVSs focus on 2D image processing, which makes it difficult to solve problems such as spatial cognition errors and low-precision interpretation. Consequently, inspired by the human visual system, an NVS with stereo vision is developed to achieve 3D object recognition, depending on the prepared ReS2 optoelectronic synapse with 12.12 fJ ultralow power consumption. This device exhibits excellent optical synaptic plasticity derived from the persistent photoconductivity effect. As the cornerstone for 3D vision, color planar information is successfully discriminated and stored in situ at the sensor end, benefiting from its wavelength-dependent plasticity in the visible region. Importantly, the dependence of the channel conductance on the target distance is experimentally revealed, implying that the structure information on the object can be directly captured and stored by the synapse. The 3D image of the object is successfully reconstructed via fusion of its planar and depth images. Therefore, the proposed 3D-NVS based on ReS2 synapses for 3D objects achieves a recognition accuracy of 97.0%, which is much higher than that for 2D objects (32.6%), demonstrating its strong ability to prevent 2D-photo spoofing in applications such as face payment, entrance guard systems, and others.

Enhanced Multiwavelength Response of Flexible Synaptic Transistors for Human Sunburned Skin Simulation and Neuromorphic Computation.

In biological species, optogenetics and bioimaging work together to regulate the function of neurons. Similarly, the light-controlled artificial synaptic system not only enhances computational speed but also simulates complex synaptic functions. However, reported synaptic properties are mainly limited to mimicking simple biological functions and single-wavelength responses. Therefore, the development of flexible synaptic devices with multiwavelength optical signal response and multifunctional simulation remains a challenge. Here, flexible organic light-stimulated synaptic transistors (LSSTs) enabled by alumina oxide (AlOX ), with a simple fabrication process, are reported. By embedding AlOX nanoparticles, the excitons separation efficiency is improved, allowing for multiple wavelength responses. Optimized LSSTs can respond to multiple optical and electrical signals in a highly synaptic manner. Multiwavelength optical synaptic plasticity, electrical synaptic plasticity, sunburned skin simulation, learning efficiency model controlled by photoelectric cooperative stimulation, neural network computing, "deer" picture learning and memory functions are successfully proposed, which promote the development for future artificial intelligent systems. Furthermore, as prepared flexible transistors exhibit mechanical flexibility with bending radius down to 2.5mm and improved photosynaptic plasticity, which facilitating development of neuromorphic computing and multifunction integration systems at the device-level.

Species independence of eye lens dimensions in teleosts and elasmobranchs.

The vertebrate eye lens grows incrementally, adding layers of elongated, tightly packed lens fiber cells at the outer margin of the lens. With subsequent growth, previously-deposited fiber cells degrade, leaving a region of fully denucleated and organelle-free cells which are responsible for the high transparency and low light scattering characteristics of the lens. The objective of this study was to determine if the horizon separating the gelatinous outer cortex of the lens from its hardened interior occurred at a consistent location within the lens of several teleost and elasmobranch fish species, and could be linked to fiber cell morphology or function. A fixed ratio of 0.69±0.01 of hardened eye lens diameter (HD) to overall eye lens diameter (LD) was observed in a broad size range of Atlantic cod (Gadus morhua), haddock (Melanogrammus aeglefinus), thorny skate (Amblyraja radiata) and round ray (Rajella fyllae). The location of the hardened lens horizon was similar to that reported for optical plasticity and spherical aberration, but not that of fiber cell denucleation, suggesting that fiber cell dehydration continues after the loss of internal organelles. Our findings support a previous suggestion that the maintenance of optical quality during fish eye lens growth requires a precisely-fixed HD:LD ratio, while the ubiquity of a fixed ratio across fish taxa may suggest that many fish species possess a common refractive index profile. The linear relationship between HD and fish length should allow fish length to be backcalculated from the diameter of the isolated lens core, thus aiding research using isotope ratios of lens laminae or inner cores to reconstruct early life history events.

1.3: The Technology and Development of Laser Display Optical Screens

Laser display has the advantages of high brightness, wide color gamut, long lifetime, low power consumption, and better eye protection, and will become the mainstream of the next generation of high‐end display; This paper mainly expounds the structure and principle of Fresnel optical screen, black grid optical screen and white plastic frame screen electric pull screen for laser display.Besides, The three kinds of optical screens are also compared in structure, material, performance and applications . Finally, the development trend of mainstream anti‐light screens is prospected.

Daylighting Performance of Sunlight Transmission and Concentration via Plastic Optical Fibers

The energy-saving technology of this thing is thriving. One of promising technology is the daylighting system via optical plastic fibers. It has many advantages, and its characteristics need further research. This paper analyses the transmission characteristics, attenuation rate, and incident angle of the optical fiber. The test data shows that the spectrum, color rendering index are good, and the energy efficiency is high. This shows that plastic optical fibres have excellent development prospects for daylighting.

Durability of the optical plastic polycarbonate under modulated blue LED irradiation at different duty cycles

In order to provide longer LED lifetimes, all LED-related components, including lenses and other optical components, need to be adapted to increasing radiation levels. Pulse width modulation (PWM) is an easy-to-implement method for driving and dimming LEDs and could be a cost-effective way to extend the lifetime of optical components installed in conjunction with the LED. In this study, polycarbonate (PC) samples were artificially aged with high-power blue LEDs using different driving modes in a newly developed test setup. The LEDs were pulse-width modulated in three different modes (50% duty cycle, 25% duty cycle, and continuous wave (CW)), while emitting the same optical power. Optical light microscopy, UV/vis spectroscopy, FTIR spectroscopy and gel permeation chromatography were performed to measure transmittance changes and general aging effects of the samples. The results indicate a substantial correlation of aging with the mode of exposure. It is found that the samples age most severely under CW irradiation, as both the decrease in transmission (at 295 nm wavelength, after 1500 h) and the sample temperature, and thus the degradation, are highest. FTIR spectroscopy showed the expected results for optical aging under LED irradiation, again the changes tended to be more pronounced for the samples irradiated without PWM. Gel permeation chromatography shows a decrease in the weight averaged molar mass, once more with the CW irradiated samples exhibiting the most significant decrease. However, optical light microscopy did not reveal any significant aging effects on the sample surface. Overall, modulation of the LED, and in particular a reduction of the duty cycle, has a positive effect on the durability of optical plastics at similar radiative energy loads. In order to explain the different aging behavior of the samples under the different driving modes, a model of the time-related temperature changes in the material during the heating phase at different duty cycles is proposed.

Star polymers with norbornene/1-octene gradient copolymer arms synthesized by an ansa-fluorenylamidodimethyltitanium-[Ph3C][B(C6F5)4] catalyst system

Cyclic olefin copolymers (COCs), among which ethylene (E)/norbornene (NB) copolymer have been commercialized, are novel optical plastics but their brittleness narrows their application fields. In this research, star polymers with NB/1-octene (O) gradient copolymer arms and cross-linked cores were synthesized by adding norbornadiene (NBD)/E or 1,11-dodecadiene (DOD) after NB/O copolymerization using a ( t BuNSiMe 2 Flu)TiMe 2 ( I )-[Ph 3 C][B(C 6 F 5 ) 4 ] catalyst system with 2,6-di- tert -butyl-4-methylphenol-treated tri- n -octylaluminum (Oct 3 Al/BHT) as a scavenger. The obtained star polymers possessed the O-rich soft segments close to the core and the NB-rich hard segments in the outer layer. The DOD-cored star polymers had a larger number of arms (15) and a higher star polymer content (68 wt%) than the NBD/E-cored ones (6 and 58 wt%, respectively). The films of the mixtures of the star and the corresponding arm polymers were molded by a melt-pressing procedure. The tensile properties of the films of the DOD-cored star polymer mixtures were significantly improved compared to those of the arm polymers. The Young's modulus, yield stress, strength, and strain at break were controlled by the NB content, the arm length, and the gradient structure of the arms. These results clarified the novelty of the star-shaped NB/ α -olefin copolymers and would expand the application fields of COCs. • Star-shaped polymers with norbornene/1-octene gradient copolymer arms were synthesized by an “arm-first” strategy. • The star-shaped polymers showed two T g values assignable to an octene-rich soft core and a norbornene-rich hard sphere. • Transparent films were obtained from the blend of the star and the arm polymers by melt processing. • The of mechanical properties of the blend films were improved compared with those of the arm polymer films. • The thermal and the star polymers were controlled by the arm length and the norbornene content.

Diffractive microstructures of zoom lenses for visible and near-infrared ranges based on novel optical plastics

Subject of study. The possibilities of minimizing the negative effect of the secondary diffraction orders of diffractive microstructures included in structurally simple zoom lenses on the formed image are considered. Objective. The study aims at demonstrating the effectiveness of novel optical plastics in the design of diffractive microstructures for the correction of chromatism and the extension of the operating spectral range of the objectives using three-component eight- and four-lens refractive–diffractive zoom lenses for the visible and near-infrared ranges as an example. Method. Combined mathematical modeling within geometrical optics approximation and rigorous diffraction theory is used. Main results. We demonstrate that, even in structurally simple objectives, new optical plastics allow bilayer diffractive microstructures to be assembled ensuring the absence of halo and any other visually observable negative effect of secondary diffraction orders on the quality of the formed image in all the specified ranges of focal length variation both under daylight and scotopic illumination. Practical significance. The reported results demonstrate the effectiveness of diversification of advanced commercially available optical plastics using the diffractive microstructures of zoom lenses as an example. These results are aimed at stimulating further efforts toward the development and mass production of optical plastics.

Photostability of polylactide with respect to blue LED radiation at very high irradiance and ambient temperature

For an overall sustainable development of lighting systems, it is crucial to establish alternatives to fossil based optical plastics. One biodegradable plastic alternative, based exclusively on renewable raw materials and having outstanding optical properties, could be the bioplastic polylactide (PLA). In order to evaluate the stability of PLA under the influence of extreme levels of optical LED radiation (λmax = 450 nm, FWHM = 16.3 nm), aging experiments were carried out over a period of 5000 h (~ 7 months) using an innovative self-developed test setup. As a reference the widely used optical plastic polycarbonate (PC) was aged under the same conditions. The novel test setup allowed aging tests at low temperatures of 23.0 and 36.1 °C (below the crystallization temperature of PLA) with irradiances of 7.9 and 16.1 kW/m2, respectively. Photodegradation tests in which temperature can be varied virtually independent of radiant flux were performed. To the best of our knowledge this is a first in degradation experiments. By this, aging can be attributed to more radiation- or temperature-related phenomena. Before, during, and after aging, optical, mechanical and chromatographic methods were used to analyze the samples. PLA was found to be largely resistant to visible blue LED radiation under the selected aging conditions. Only an increase in surface hardness and stiffness, indicating embrittlement, was observed. In contrast, even at the low temperatures used in these experiments, PC shows a significant decrease in transmission in the short-wavelength range of up to 17.0% after prolonged aging. Moreover, known degradation products (by FTIR spectroscopy), a decrease in molar mass (5.1%) and a trend increase in Martens hardness and indentation modulus, were detected for all PC of samples.

Confining Carboxylized Carbon Nanotube for Phosphorescence Afterglow with Optical Memory Plasticity

AbstractAfterglow materials are of primary interest in optoelectronics and bioelectronics. Here, a long‐lived phosphorescence afterglow is reported from carboxylated carbon nanotubes (c‐CNTs) confined within boron oxynitride (BNO). The formation of covalent and hydrogen bonds in c‐CNT@BNO enhances the rigidity of the hybrid structure and alleviates the non‐radiative deactivation of excited triplet states, leading to room‐temperature phosphorescence (RTP). The afterglow material exhibits an ultra‐long RTP lifetime of up to 476.6 ms, with an afterglow time of 4.0 s, distinguishable by naked eyes. This unprecedented feature makes c‐CNT act like a light‐sensitive neuron and it is possible to achieve memorizing−forgetting behavior in the form of optical memory plasticity, owing to photons’ capture‐and‐slow‐release process. In analogy to the biological brain, both memory strength and forgetting time are proportional to learning exercise, including the intensity and time of irradiation training. The study provides an effective protocol for the synthesis of afterglow nanomaterials, extending their application to brain‐like intelligent technology.

Photonic implementation of spike timing dependent plasticity with weight-dependent learning window based on VCSOA

Based on the well-known Fabry–Pérot approach, after taking into account the variation of bias current of the vertical-cavity semiconductor optical amplifier (VCSOA) according to the present synapse weight, we implement the optical spike timing dependent plasticity (STDP) with weight-dependent learning window in a VCSOA with double optical spike injections, and numerically investigate the corresponding weight-dependent STDP characteristics. The simulation results show that, the bias current of VCSOA has significant effect on the optical STDP curve. After introducing an adaptive variation of the bias current according to the present synapse weight, the optical weight-dependent STDP based on VCSOA can be realized. Moreover, the weight training based on the optical weight-dependent STDP can be effectively controlled by adjusting some typical external or intrinsic parameters and the excessive adjusting of synaptic weight is avoided, which can be used to balance the stability and competition among synapses and pave a way for the future large-scale energy efficient optical spiking neural networks based on the weight-dependent STDP learning mechanism.

Computing and comparative analysis of topological invariants of Y‐junction carbon nanotubes

AbstractRecent findings of diverse forms of carbon nanostructures have encouraged research on their applications in several areas. They are used as a structural material in electronic and optical devices, involving transistors, photodetectors, plastic, biological sensors, pharmaceutical and medicine, and drug delivery systems. Since the discovery of Y‐shaped carbon nanotubes (CNTs) junctions, they have drawn interest for future electron devices, for example, three‐terminal transistors, amplifiers, and switches. A topological index is a number that is used to study the physicochemical properties of chemical structures. In this paper, we are providing topological properties of CNT Y‐junctions. The results obtained for different types of Y‐junction graphs appeared with comparisons. According to the best of our knowledge and literature, this is the first report about topological indices on this class of CNT junctions.

A New Conformal Cooling System for Plastic Collimators Based on the Use of Complex Geometries and Optimization of Temperature Profiles.

The paper presents a new design of conformal cooling channels, for application in collimator-type optical plastic parts. The conformal channels that are presented exceed the thermal and dynamic performance of traditional and standard conformal channels, since they implement new sections of complex topology, capable of meeting the high geometric and functional specifications of the optical part, as well as the technological requirements of the additive manufacturing of the mold cavities. In order to evaluate the improvement and efficiency of the thermal performance of the solution presented, a transient numerical analysis of the cooling phase has been carried out, comparing the traditional cooling with the new geometry that is proposed. The evolution of the temperature profile versus the thickness of the part in the collimating core with greater thickness and temperature, has been evaluated in a transient mode. The analysis of the thermal profiles, the calculation of the integral mean ejection temperature at each time of the transient analysis, and the use of the Fourier formula, show great improvement in the cycle time in comparison with the traditional cooling. The application of the new conformal design reduces the manufacturing cycle time of the collimator part by 10 s, with this value being 13% of the total manufacturing cycle of the plastic part. As a further improvement, the use of the new cooling system reduces the amount of thickness in the collimator core, which is above the ejection temperature of the plastic material. The improvement in the thermal performance of the design of the parametric cooling channels that are presented not only has a significant reduction in the cycle time, but also improves the uniformity in the temperature map of the collimating part surface, the displacement field, and the stresses that are associated with the temperature gradient on the surface of the optical part.