Fabrication Of Optical Devices Research Articles

Topology Optimization Enabled High Performance and Easy‐to‐Fabricate Hybrid Photonic Crystals

AbstractPhotonic crystals (PtCs) can confine and guide electromagnetic waves within specific frequency ranges, forming the foundation for promising optical applications. To numerically design PtCs with broad bandgaps, materials with high dielectric constants are favored. However, fabricating these high dielectric constant materials into microstructures is extremely challenging and it suffers from limitation of low fabricating resolution. To address this problem, this paper proposes hybrid microstructures composed of an easy‐to‐fabricate core and a high dielectric constant coating layer, which leverages the strength of both materials. This paper establishes a topology optimization algorithm to generate these PtCs with maximized bandgaps. Numerical examples demonstrate the effectiveness of the proposed method in generating optimized unit cells for both transverse magnetic (TM) and transverse electric (TE) modes. The hybrid PtCs offer unprecedented opportunities for the fabrication of optical devices, encouraging further research on multimaterial optical systems and advanced optimization methods to explore photonic bandgap materials beyond those offered by the current photonic technology.

Biobased Sulfur- and Phosphate-Containing High-Refractive-Index Polymers: Substituent Effects on Optical Properties of Polymers.

Four biobased phosphate-containing aryl monomers with methoxy, allyl, and vinyl groups as substituents have been successfully synthesized. Copolymerizing these monomers with thiophenol or mercaptans via the photoclick thiol-ene reaction gives the polymers with refractive indices (nD) of 1.63-1.70 and Abbe numbers (vD) of 12.8-38.5. An investigation of the relationship of the vD values with the substituents on the benzene rings of the monomers indicates that methoxy and vinyl groups can collectively increase the vD values. In comparison with allyl groups, vinyl groups endow the polymers with both higher nD and vD. Moreover, these polymers also display high transmittance, high thermostability, and low haze values in the visible-light region, suggesting that these biobased functional monomers are satisfactory precursors used in the fabrication of optical devices.

A methodical investigation on stilbazolium derivative substituted with 2,4-Dichlorobenzaldehyde as a donor: An effective crystal for optical device fabrication

For a couple of decades, nonlinear optics (NLO) has garnered significant attention due to its widespread application in optical systems. In this viewpoint, a new 2-[2(2,4-Dichloro-phenyl)vinyl]methyl-1-pyridinium iodide (DCPI) crystal was grown through slow evaporation process for NLO application. Single Crystal X-ray diffraction (SCXRD) study reveals that the DCPI crystallized centrosymmetric (P-1) space group. The CHN elemental analysis and NMR spectroscopy assess the purity of the material. The vinyl (CC) group formation in DCPI was asserted by the Fourier-transform infrared (FT-IR) spectrum. The Hirshfeld surface analysis confirms the presence of hydrogen bonds in the crystal structure through its contribution percentage (27 %) to the overall intermolecular interaction. DCPI crystal exhibits 80 % transparency in the visible region. Luminescence studies assess the green light-emitting characteristics of the DCPI crystal. The etching and Atomic Force Microscopy (AFM) studies confirm that the DCPI crystal has a flat surface with minimum dislocations. Z-scan studies found the third-order nonlinear characteristics of the crystal. Overall, the article illustrates the appropriateness of DCPI crystal in fabricating optical devices through its significant optical characteristics.

Crystal growth, linear optical, thermal, mechanical and third-order nonlinear optical properties of 1,3-diphenyl prop‑2-en-1-one single crystals

This work brings out the viability of the chalcone derivative (E)-1,3-diphenyl-2-propen-1-one (DPP) for industrial applications in nonlinear optical technology and device fabrication, through investigations on its crystal structure and nonlinear optical properties. The unit cell features of the DPP single crystals grown by slow evaporation solution growth method have been determined and hkl values indexed. The optical transparency of DPP in the near infrared and visible range is found to be admirable and an optical bandgap of 3.42 eV is revealed in the UV–Vis-NIR analysis. The work hardening coefficient (n) of DPP, determined as 2 from Vickers microhardness measurement, shows the moderate mechanical strength of the crystal. The Laser Damage Threshold value of 3.9 GW/cm2 sheds light on the high tolerance of DPP to optical damage and suggests its suitability in device fabrication. The potential of DPP crystal in nonlinear optical applications is suggested from its superior value of 1.16×10−7 esu for third order susceptibility and appealing values of other nonlinear optical parameters.

Theoretical exploration of binary mixtures derived from hydrogen bond liquid crystalline soft materials for optical device fabrication

Binary mixtures are obtained from 4-Nitrobenzaldehyde (NBA), 4-(heptyloxy)benzoic acid (7OBA) and 4-(octyloxy)benzoic acid (8OBA) abbreviated as NBA + 7OBA and NBA + 8OBA. Density Functional Theory (DFT) is used to optimize the resultant molecular structures. HOMO–LUMO and NBO analysis are adapted in obtaining the charge transfer phenomenon of the binaries. Molecular electrostatic Potential (MEP) analysis reveals the active sites of liquid crystals. Atomic charge distribution of the binary mixture is investigated theoretically. Topological analysis is carried out to understand the intermolecular interaction between non mesogenic NBA and mesogenic precursors along with nonlinear optical properties. The results obtained are correlated with the experimental data obtained.

New light-illuminated silk road: emerging silk fibroin-based optical biomedical sensors.

Biomedical silk protein optics has become the subject of intensive research aimed at solving the challenges associated with traditional medical devices in terms of biocompatibility and performance balance. With its significant potential for biomedical applications in the field of drug storage and wound monitoring, it is dedicated to reducing the perturbation of neighbouring tissues. The transparency and biocompatibility of silk proteins make them ideal materials in the field of optical device fabrication, effectively overcoming the challenges posed by conventional materials. In this paper, we explore in detail the complex aspects of the design, synthesis and application related to biomedical silk protein optical devices and comprehensively analyse the potential use of silk protein-centric microstructures (e.g., micropillars, microneedles, and photonic crystals) in the development of optical devices. This review also offers insights into the challenges of applying silk protein optical devices in healthcare and their future trends, aiming to provide a comprehensive overview of the advances, potential impacts and emerging research directions in the field of biomedical silk protein optical devices.

Brushy C-Decorated BiTe-Based Thermoelectric Film for Efficient Photodetection and Photoimaging.

Current strategies for simultaneously achieving high thermoelectric performance and high light absorption efficiency still suffer from complex steps and high costs. Herein, two kinds of amorphous thermoelectric films of n-type Bi2Te3 and p-type Bi0.5Sb1.5Te3 with high Seebeck coefficients were prepared by pulsed laser deposition (PLD) technology. In addition, C-decorated films with excellent light absorption efficiency at the junction of the thermoelectric legs were prepared by simple drop coating and reactive ion etching (RIE) method. The TE/C-RIE composite device exhibits excellent photodetection performance under the conditions of simulated natural light, monochromatic light, and high-frequency chopping. The maximum responsivity and specific detectivity of the device can reach 153.58 mV W-1 and 6.97 × 106 cm Hz1/2 W-1 (under simulated natural light), respectively. This represents an improvement rate of 85.91% compared to that of the pure TE device. Benefiting from the excellent photodetection efficiency of the device and integration advantage of PLD technology, the composite structure can be expanded into integrated photoimaging devices. The accurate identification of patterned light sources with letters (T, J, and U) and digitals (0-9) was successfully realized by associating the response electrical signals of each electrode with the position coordinates. This work provides valuable guidance for the design and fabrication of wide-spectrum photodetectors and complex optical imaging devices.

Exploring the Structural, Optical and Photoluminescence Performances of CuCo2O4 and ZnMn2O4 Alloying

The performance of the structural, linear/ nonlinear optical and photoluminescent properties of CuCo2O4 and ZnMn2O4 alloying was investigated. (1−x)CuCo2O4/(x)ZnMn2O4 (x = 0, 0.10, 0.15, 0.2) samples were prepared by the sol-gel and hydrothermal procedures. Synchrotron X-ray diffraction measurements were employed to investigate the structural and microstructural properties applying the Rietveld refinement method. Fourier transform infraed and Raman techniques were applied to explore the structures’ variation and chemical bonding of the obtained phases. Ultraviolet–visible diffuse reflectance spectroscopy measurements were collected to explore the optical properties. The optical band gap values were determined using the Kubelka-Munk method. All samples exhibited two band gaps in the visible-NIR regions. Upon composing with ZnMn2O4, the band gaps of CuCo2O4 declined for x = 0.1 and 0.15, followed by an increase at x = 0.2. The possible electronic band structure of the samples and the photoluminescent performance of the prepared samples was investigated. The observed PL patterns manifest wide and asymmetrical emissions. The CIE chromaticity diagram for all samples was plotted. The obtained findings of (1−x)CuCo2O4/(x)ZnMn2O4 nominate their efficient role in optical device fabrication and photocatalyst applications.

Electrochemical study and structural comparison of Ni electrodepositions on W/Si and Cr/C multilayered structure films

The Ni electrodeposition combined with multilayered structure film is a promising strategy in modern optical manufacturing, while less effort has been devoted to comprehending the electrochemical reaction process, which is essential for their practical applications. In view of this, the initial reduction dynamics and nucleation mechanisms of Ni electrodepositions on multilayer W/Si and Cr/C films were analyzed in this work, and the morphological, crystal, and mechanical characteristics of produced Ni electrodeposits were further determined and compared. The results show that the considerably irregular crystals accompanied by high tensile stress of 119.5 MPa were formed for the Ni electrodeposit on W/Si film, which were mainly attributed to the progressive nucleation process with more severe side reaction of hydrogen evolution. By contrast, the instantaneous nucleation mode with lower reduction resistance were revealed for the Ni electrodeposition on Cr/C film, which presented a comparatively fine–grained texture, less roughness, and smaller stress structure. To summarize, the more stable electrochemical reaction process and improved structure uniformity are obtained for the Ni electrodeposition on metal/C–based film, which offers a theoretical guidance for optimized fabrication of multilayer optical devices in extreme ultraviolet, x-ray, and neutron focusing fields.

Azimuthal rotation-controlled nanoinscribing for continuous patterning of period- and shape-tunable asymmetric nanogratings

We present an azimuthal-rotation-controlled dynamic nanoinscribing (ARC-DNI) process for continuous and scalable fabrication of asymmetric nanograting structures with tunable periods and shape profiles. A sliced edge of a nanograting mold, which typically has a rectangular grating profile, slides over a polymeric substrate to induce its burr-free plastic deformation into a linear nanopattern. During this continuous nanoinscribing process, the “azimuthal angle,” that is, the angle between the moving direction of the polymeric substrate and the mold’s grating line orientation, can be controlled to tailor the period, geometrical shape, and profile of the inscribed nanopatterns. By modulating the azimuthal angle, along with other important ARC-DNI parameters such as temperature, force, and inscribing speed, we demonstrate that the mold-opening profile and temperature- and time-dependent viscoelastic polymer reflow can be controlled to fabricate asymmetric, blazed, and slanted nanogratings that have diverse geometrical profiles such as trapezoidal, triangular, and parallelogrammatic. Finally, period- and profile-tunable ARC-DNI can be utilized for the practical fabrication of diverse optical devices, as is exemplified by asymmetric diffractive optical elements in this study.

Advances in laser‐based manufacturing techniques for specialty optical fiber

AbstractAs demand for customized specialty fibers grows, standardized production methods face challenges. This article reviews industry standards and discusses potentially disruptive techniques that enable rapid prototyping and fabrication of optical fiber devices. Furthermore, we showcase laser powder deposition's (LPD) potential for additive manufacturing (AM) of customized glass structures. In the case of, for example, fiber preforms, although the feasible size is smaller than the industry standard, utilizing laser‐based manufacturing techniques for a small batch production presents an attractive avenue for rapid prototyping and expedites material and design optimization. In the realm of AM of glass, LPD offers numerous benefits, including minimal shrinkage, high densification, and the ability to tailor glass composition to achieve desired optical properties. The article reviews the latest achievements and highlights future directions in this technology.

Broadband Green Luminescence and Phase Transition in Low-Dimensional Organic-Inorganic Hybrid Iodate.

Organic-inorganic hybrid iodide systems, which can form highly ordered chromophores and uniformly oriented transition dipole moments, serve as optimal host-guest systems for the fabrication of micrometer-scale optical devices. In particular, those with low-dimensional structures can exhibit strong quantum-limited and highly localized charges, enabling the generation of high exciton energies and stable excitation emission. In this study, we report a novel instance of an organic-inorganic hybrid iodate, (C13H11N2)(IO3), which was synthesized by incorporating the optically active organic compound, 9-aminoacridine. Upon crystallization in the monoclinic space group P21/c, this compound exhibits a direct optical band gap of 2.66 eV. The incorporation of discrete organic units within the low-dimensional structures induces pronounced local charges, culminating in broadband green luminescence with a peak at 540 nm under UV excitation. This corresponds to the CIE coordinates (0.37, 0.56). A potential phase transition was inferred through a comprehensive analysis of the variable temperature structure and emission spectra. Furthermore, first-principles calculations revealed the pivotal role of organic cations in facilitating broadband luminescence.

GaN integrated optical devices for glycerol viscosity measurement.

This Letter presents the fabrication and characterization of a chip-scale GaN optical device for measuring glycerol viscosity. The monolithically integrated GaN chip with a size of 1 × 1 mm2 comprises a light-emitting diode (LED) and a photodiode (PD) on a transparent sapphire substrate. The glycerol droplet applied to the device acts as a medium for coupling light from the LED to the PD. When a mechanical impulse is applied, the droplet undergoes a damped vibration that depends on its viscosity, causing a change in its shape and altering the path of light propagation. The viscosity of the glycerol sample can be determined by obtaining the rate of attenuation of the measured photocurrent signals. The proposed unit offers a fast time response in microseconds and requires only a small sample volume of 5 µl. The developed device is highly suitable for the practical measurement of glycerol viscosity due to its miniaturization, low cost, and ease of operation without the need for external optical components.

Understanding the effects of annealing induced structural transformations on the UVC absorbance and other optical properties of RF sputter deposited Ga2O3 thin films

Gallium oxide (Ga2O3) is a transparent material with high absorption in the UVC region of the electromagnetic spectrum and hence is a very important candidate in the field of short wavelength optical device fabrication. A proper understanding of the different optical parameters is necessary for developing more efficient coatings and devices. In this work, changes in the optical behavior of Ga2O3 thin films due to post-deposition annealing (at temperatures 300 °C–900 °C) are discussed in detail. Structural, surface morphological and compositional modifications of the films are identified using the x-ray diffractometer, scanning electron microscopy and x-ray photoelectron spectrometer techniques, respectively. At 900 °C, a highly stable monoclinic β phase of Ga2O3 is obtained. The optical transmittance spectra acquired using UV–Vis spectroscopy indicate an improved UVC absorbance of the β-Ga2O3 films with an excellent visible transmittance (>80%). The structural transformation from amorphous to crystalline β-Ga2O3 phase and the associated reduction in defect density is found to modify other optical attributes, like the bandgap energy, Urbach energy, dispersion parameters, etc.

Electronic structure and optical properties of In- and Vacancy-doped 6H-SiC: a first-principles study.

The paper aims to investigative the cacusesand impactsof In- and Vacancy-doped to 6H-SiC, expecting that improving optical properties ofmaterials.Design-Using the first-principles calculations, we discuss the electronic structure and optical properties of different doped 6H-SiC systems. The results show that In-doped 6H-SiC becomes a direct bandgap p-type semiconductor and the energy bandgap is reduced from the intrinsic 2.059 to 1.515eV. We demonstrate the stability of the systems through the formation energy analysis, meanwhile identify their physical origins and discuss applications of all structures in electronic devices within optical analysis. Find the energy beginning values of the VSi-doped and VC-doped systems' optical absorption spectrums and extend to 0.4 2eV and 0.11eV respectively compared with the original 3.23eV. In the visible light region, the reflectivity images of the VC/VSi and (In, VSi)-codoped systems rise obviously. The optical properties of all doping systems were analyzed to be improved compared with the intrinsic, all above mentioned provide a theoretical basis for the fabrication of spintronic and optical devices.

Conducting Gold Nanoparticle Films via Sessile Drop Evaporation.

The deposit patterns obtained from the evaporation of drops containing insoluble solute particles are vital for several technologies, including inkjet printing and optical and electronic device manufacturing. In this work, we consider the evaporation of an aqueous reaction mixture typically used for gold nanoparticle (AuNP) synthesis. The patterns obtained from the evaporation-driven assembly of in situ generated AuNPs are studied using optical microscopy and SEM analyses. The evaporation of drops withdrawn at different reaction times is found to significantly influence the distribution of AuNPs in the dried patterns. The evolution of the deposit patterns is also explored by drying multiple drops on the solid substrate, wherein a drop of a fresh reaction mixture is introduced over the deposit pattern left by the evaporation of the drop dispensed at an earlier time. Using quantitative image analysis, we show that the interparticle separation between the AuNPs in the dried patterns left on the solid substrate decreases when the number of drops is increased. We find optimal conditions to achieve solid-supported AuNP films, wherein the particles are in close physical contact, leading to a conducting deposit. The current through the AuNP deposit is found to increase with increase in the number of drops due to evaporation-driven self-assembly of AuNPs into branch-like structures with reduced interparticle separation. In addition, we also show that it is possible to produce conducting AuNP deposits by drying multiple drops withdrawn from the same reaction mixture. The evaporation-driven assembly of the in situ grown nanoparticles from a reaction mixture presented in this work can be further exploited in optical and electronic device fabrication.

Magnetic assembly of plasmonic chiral superstructures with dynamic chiroptical responses.

Plasmonic nanostructures exhibiting dynamically tunable chiroptical responses hold great promise for broad applications such as sensing, catalysis, and enantioselective analysis. Despite the successful fabrication of chiral structures through diverse templates, creating dynamic chiroptical materials with fast and reversible responses to external stimuli is still challenging. This work showcases reversible magnetic assembly and active tuning of plasmonic chiral superstructures by introducing a chiral magnetic field from a cubic permanent magnet. Manipulating the strength and direction of the magnetic field controls both the chiral arrangement and plasmonic coupling of the nanoparticle assembly, enabling fast and reversible tunability in not only the handedness of the superstructures but also the spectral characteristics of their chiroptical properties. The dynamic tunability further enables the fabrication of color-changing optical devices based on the optical rotatory dispersion effect, showcasing their potential for application in anti-counterfeiting and stress sensors.

Multiwavelength Quantum Correlated Photon Pair Generation for Quantum Entanglement Key Distribution

With the rapid advancement of quantum information technology, fully connected multi-user quantum entanglement distribution networks have garnered increasing attention. Among these, multi-wavelength quantum light sources are key devices for establishing connections between multiple users. Despite recent impressive advances, it remains challenging to increase the wavelength number of photon pairs due to limitations in the design and fabrication of nonlinear optical devices. This work explores the potential of silicon nitride (Si<sub>3</sub>N<sub>4</sub>) microring resonators (MRRs) as scalable platforms for multi-wavelength quantum light sources.<br>In this work, we conduct a comprehensive analysis of the key design parameters of the Si<sub>3</sub>N<sub>4</sub> MRRs, including waveguide dimension, resonator dispersion, and coupling condition, to optimize photon-pair generation. Based on these parameters, a Si<sub>3</sub>N<sub>4</sub> MRR with a free spectral range of 20 GHz and an average quality factor of 1.6 million is designed and fabricated. This small free spectral range enables the generation of more channels of correlated photon pairs using the same wavelength resources. The high-quality of the resonator facilitates the high photon pair generation rate, which are critical for quantum entanglement distribution. With a continuous-wave pump laser, correlated photon pairs across a wide spectral range are generated through the spontaneous four-wave mixing (SFWM). The coincidence-to-accidental ratio (CAR) measurements verify the strong quantum correlation between photon pairs, highlighting the reliability of the system for entanglement distribution. Furthermore, the generation and output characteristics of quantum-correlated photon pairs are experimentally investigated with a tunable bandpass filter. The results demonstrate that the successful generation of 71 wavelength-correlated photon pairs within a 25.6 nm spectral range is achieved as shown in the Figure A. Our results pave the way for the development of multi-wavelength quantum light sources with Si<sub>3</sub>N<sub>4</sub> platform, thereby advancing the multi-user quantum networks.

Theoretical study on photoinduced charge transfer in one-photon and two-photon absorption of branching oligofluorenes

Oligofluorenes have been identified as very promising two-photon absorption (TPA) materials and present great application potential for the fabrication of nonlinear optical devices, but the TPA mechanism and corresponding electron excitation properties have not been studied. Here, the photoinduced charge transfer characteristics of V-shaped and Y-shaped branching oligofluorenes that consist of two and three fluorene units in each branch during one-photon absorption (OPA) and TPA processes are analyzed theoretically using the density functional theory and visualization sum-over-states model. The calculated results show that the OPA intensity and TPA cross-section are significantly enhanced by increasing the branch length or changing the structure from V-shaped to Y-shaped. The long-distance charge transfer only occurs on the second transition of TPA at high excited states. Compared to Y-shaped molecules, V-shaped structures exhibit a stronger cooperative effect among the different branches.

Surface-Guided Crystallization of Xanthine Derivatives for Optical Metamaterial Applications.

Numerous bio-organisms employ template-assisted crystallization of molecular solids to yield crystal morphologies with unique optical properties that are difficult to reproduce synthetically. Here, a facile procedure is presented to deposit bio-inspired birefringent crystals of xanthine derivatives on a template of single-crystal quartz. Crystalline sheets that are several millimeters in length, several hundred micrometers in width, and 300-600nm thick, are obtained. The crystal sheets are characterized with a well-defined orientation both in and out of the substrate plane, giving rise to high optical anisotropy in the plane parallel to the quartz surface, with a refractive index difference Δn ≈ 0.25 and a refractive index along the slow axis of n ≈ 1.7. It is further shown that patterning of the crystalline stripes with a tailored periodic grating leads to a thin organic polarization-dependent diffractive meta-surface, opening the door to the fabrication of various optical devices from a platform of small-molecule based organic dielectric crystals.