This PDF file contains the front matter associated with SPIE Proceedings Volume 11467, including the Title Page, Copyright information, and Table of Contents.

Far-infrared wavelength range (30μ- 1000μm) is an important spectral region for several applications such as thermal imaging, chemical sensing, astronomical imaging, among others. Therefore, miniaturization of far infrared (FIR) optical devices is of great technological interest. Recently, anisotropic 2D van der Waals crystals have garnered substantial attention for potential applications in the area of visible to mid-infrared (MIR) photonics. However, these materials have been relatively less explored for their applications in FIR spectral region for photonic devices. Molybdenum Trioxide (α-MoO₃) - a member of the van der Waals semiconductor family exhibits strong in-plane anisotropy, using which one can engineer the polarization state of the incident light - a property highly relevant for photonic device applications. As example device applications, in this work we investigate the potential of α-MoO3 for two optical components in the FIR spectral region (265 cm^-1-360 cm^-1), i.e. polarizer and waveplates. We evaluate the performance metrics of our proposed FIR polarizer system using a theoretical model and predict a large extinction ratio (> 30 dB). Secondly we optimize the thickness of α-MoO₃ for waveplate application. Our theoretical analysis will pave the way for the development of efficient thin-film based photonic devices for FIR spectral region.

To build Photonic CMOSFETs, a laser diode or LED is fabricated in the CMOS drain regions, and photon sensors, or APDs (Avalanche Photo Diodes) are fabricated in the CMOS channel / well regions. MOSFET, laser, APD are combined as one integral transistor. Selective epitaxial films (compound direct bandgap materials) are deposited on silicon or underlying GaAs to form a laser. When MOSFET is on, light emitted from the laser is absorbed by the APD, causing an avalanche breakdown. The high breakdown current flows through the MOSFET drain region and the laser, to produce more lights. When MOSFET is off, laser and APD are also turned off. Nonlinear optical materials are fabricated inside the Photonic CMOSFETs to modulate the incident and outgoing laser light signals. In addition to electronic signals in metals, CMOS transistors also communicate with focused laser beams - no metals – using optic waveguides. Device models, layout and circuit designs need to adapt to optoelectronic micro networks for expanded fan-out and functionalities.

Metasurfaces are subwavelength artificially engineered devices which serve as the best alternative for conventional bulk optical components, owing to their unique capability to control and manipulate the intensity, phase, and polarization of the electromagnetic waves. They have emerged as an exceptional podium for the miniaturization and on-chip implementation of many diverse prodigies such as 3D imaging, lensing, beam shaping and light-twisting, etc. Regardless of the rapid development in this domain, metasurfaces exhibiting metallic scatterers are still subjected to poor transmission efficiency due to high ohmic losses and optical absorptivity. In this work, we demonstrate a transmission-based highly efficient alldielectric metasurface to generate finite energy accelerating 1D and 2D airy beams at the visible wavelength of 633 nm by concurrently manipulating the phase and the amplitude of the cross-polarized transmitted light. The proposed metasurface employs hydrogenated amorphous silicon(a-Si:H) nanoresonators which offers a remarkable lead in term of efficiency over metals and other high-index dielectrics (such as TiO₂ and GaN) with respect to cost, CMOS compatibility and ease of fabrication. Here the orientation of the nano-bars is varied to control the phase and polarization whereas its geometric parameters are optimized to tune the cross-polarized transmission amplitude. In comparison to the previously reported work, we achieved sufficiently high cross-polarized transmission efficiency i.e., 73%. Owing to its unique characteristics of being self-accelerating, diffraction free and self-healing, this Airy beam based metasurface will aid us to develop planar 2D devices for plentiful applications such as Super-resolution fluorescence imaging, light-sheet microscopy, nano-particles trapping, and optical bullets.

Arbitrary topology designs cause manufacturing challenges due to feature sizes that are difficult to perform with current industry-standard optical lithography. To overcome this problem, we employed generalized Bruggeman effective medium theory (EMT) to binarize a continuous index arbitrary topology designed by the objective first algorithm. Different types of power splitters such as 1x2, 1x4 are generated by the inverse design algorithm and then binarized by the proposed EMT approach. The designed final structures are compact with a binary index variation that achieve up to 95% efficiency over a broad bandwidth. The presented approach provides a different perspective of view to binarize an arbitrary topology generated by the objective first algorithm. Binarization of other computationally designed photonic structures is also feasible and the proposed method helps the fabrication process by resolving the difficulties emerging from the unattainable feature sizes.

Recent observations of ferroelectricity in mixed hafnia and zirconia thin films have been surprising, since the bulk crystal phases of the individual materials are non-polar in the absence of applied electric fields. The ferroelec- tricity can be traced back to a metastable, polar orthorhombic phase, which however is nearly indistinguishable from the tetragonal phase in grazing incidence X-ray diffraction. This indicates that better tools for optical characterization and identification of thin film crystalline phases are needed. Here we describe a first-principles methodology for obtaining a collection of optical properties such as the dielectric and electro-optical tensors, as well as infrared and Raman spectra. We illustrate how these can be used to guide material characterization of thin film dielectrics, by identifying distinct fingerprint signatures for each phase, which potentially can be used for real-space identification and characterization of ferroelectric regions.

In this study, we applied the Artificial Bee Colony (ABC) algorithm to the inverse design of photonic crystals (PhCs). The ABC algorithm was implemented to maximize photonic band gaps (PBG) in two-dimensional PhCs. We assumed PhCs comprised of silicon and air, in a triangular lattice. The band diagrams were calculated by the finite element method (FEM) in the frequency domain. The ABC algorithm presented PChs with larger PBGs than those obtained from a genetic algorithm.

Radiative cooling is an emerging strategy to achieve cooling without using electricity, where a surface has high solar reflectance and high thermal emittance simultaneously. Porous polymer paint is a scalable approach to realize radiative cooling. For instance, porous poly(vinylidene fluoride-co-hexafluoropropene) (P(VdF-HFP)) coatings exhibit near-perfect solar reflectance Rsolar (> 0.96) and long-wave infrared (LWIR) emittance εLWIR (~ 0.97) for radiative cooling. In this presentation, I will discuss the principle, manufacturing of such porous film. Methods to switch the optical/thermal properties from radiative cooling to solar absorption will also be discussed, which represents an “ice-house” to “green-house” transition useful for tuneable radiative cooling at night and potentially, thermal camouflaging. At the end, strategies to achieve colored radiative cooling will be discussed too

Nanoimprint Lithography (NIL) has demonstrated its value in manufacturing nanostructures with extremely tight tolerances for the optics industry. Doing NIL process on single samples in the lab has been displayed for a long time in industry and academia. Scaling up from one good sample to full wafer and wafer to wafer uniformity for many wafers in a row, has some obstacles to overcome. In this paper, we discuss the process repeatability of manufacturing nanostructures starting from basic line/space through various other periodic and meta structures. Demonstrating the manufacturing capability using NIL for pattering also includes the other related process steps such as thin films and etching. We discuss key metrology, process control characterization, and process stability which include thin film RI uniformity, master to print replication uniformity, and post etch structural critical dimensions uniformity (CDU). Our NIL process has achieved 1.0nm σ on line widths at 45nm. This precision of replication includes all variation introduced from multiple stamps, wafer to wafer prints, and multiple sites within the wafer. This level of process control at the masking layer needs to be maintained for the finished structure.

Patterning graphene into nanostructures enables the coupling of free space radiation to plasmons in graphene. These plasmons are highly tunable and have been used in such applications as tunable filters and chemical sensors in the THz and mid-infrared ranges, with graphene structures with characteristic dimensions of 15 nm of greater. Here, we will demonstrate that block copolymer based fabrication can create sub 15 nm plasmonically active graphene nanostructures in a scalable, efficient, and repeatable manner. Furthermore, we will report the first measurement of a near-infrared graphene plasmon resonance and discuss some implications for next-generation optoelectrical devices.

In the past few years, the textiles are undergoing transformations with the integration of smart technologies and are termed as smart textiles or e-textiles. The major limitation of e-textiles is the absence of lightweight integrable and non-exploding energy storage. Here, we demonstrate the prototype of the 3D laser printed large-scale stretchable graphene waterproof energy storages of size 100 cm², which are embedded into the textiles with an areal capacitance of 49 mF cm^-2, an energy density up to 6.73 mWh cm^-2, a power density up to 2.5 mW cm^-2 and a capacitance retention up to 94%.

Optical materials with a high refractive index, such as silicon, are receiving increasing attention in the photonics research community. When structured on the nanoscale, these materials display optical Mie-type resonances with low loss and effective manipulation of light. High-refractive-index nanostructures are therefore key ingredients in the design of novel nanophotonic devices and have great technological potential, ranging from surface coloration to ultra-thin optical devices. The performance of such optical devices is directly linked to the electromagnetic near field of high-refractive-index nanostructures. Unfortunately, the optical near field is extremely challenging to measure, and it involves dedicated near-field instruments. Here, we demonstrate that Raman spectroscopy – a technique available in laboratories worldwide – can be turned into a versatile near-field instrument for high-refractive-index nanophotonics Raman spectroscopy measures the inelastic scattering of photons due to phonons and its intensity scales dramatically with the electric near-field intensity. We exploit this property to measure the near-field enhancement produced by two important classes of optical resonances in high-refractive-index nanostructures; Fabry-Pérot and Mie resonances. We realize these resonances in judiciously sized silicon thin films and nanodisk arrays, respectively, and provide experimental characterization using a novel Raman setup with tunable excitation wavelength. An intuitive theoretical model based on the enhancement of the stored electric energy corroborates our experimental findings.

We report the wavefront analysis in subwavelength dielectric metalenses. Experimentally, Shack-Hartmann wavefront sensor systems were employed to obtain lens aberrations and they were compared with theoretical calculations using Finite-difference Time-domain (FDTD) simulation. We were able to compute modal coefficients with Zernike functions implemented in Matlab. The measured and simulated wavefronts from metalenses were expressed as a sum of Zernike modes, typically 36 modes including the main 6 coefficients: defocus, vertical and obliques astigmatisms, vertical and horizontal comas, and spherical aberration. To assess the quality of the results, we reconstructed to wavefront data from the computed Zernike coefficients and compared to the originals as well. These results give us more confidence and accurate information about the effectiveness for practical use of metalenses.

To improve upon a fundamental limit on transmission of an in-plane plasmonic metasurface device, Out-of-Plane (OOP, i.e. 3D-thin-film) metasurface plasmonic phase elements were designed using genetic algorithm techniques to work in the infrared, λ = 8 μm, and these were fabricated as a beamsteerer using membrane projection lithog- raphy and characterized using scatterometry to measure the Bidirectional Transmittance Distribution Function (BTDF) of the device. BTDF was measured as a function of scatter angle for four different polarization con- figurations: co-polarization and cross-polarization for two orthogonal linear polarization states and simulated using a finite element method (FEM) solver to generate the near fields of each phase element of the device and a Stratton-Chu formulation to propagate to the far field. The measurements showed the designed beamsteering from the device, but also a strong zero-order diffraction not present in the simulations. This disagreement be- tween models and measurements motivated this study to understand what was causing the differences. To that end, FEM models which reduced the coupling between adjacent elements of the beamsteerer were designed to examine methods that would better simulate measurements. Details of the models are discussed. Future work will focus on finding the root cause for this decrease in coupling.

In this work, we present the performance analysis of the Cu(InGa)Se2 (CIGS) thin-film solar cell by exploring the physics of varying CIGS thickness, bandgap, and the device temperature. The thickness optimization of the CIGS layer is important as this lowers the large-scale manufacturing cost and eliminates the issues associated with the handling of bulky conventional solar cells. The chalcopyrite CIGS material bandgap varies from 1eV to 1.7 eV depending upon the value of ‘x’ in the formula CuIn1-xGaxSe2. The bandgap can be engineered by varying the gallium (Ga) and indium (In) composition in CuIn1-xGaxSe2. The structure is numerically simulated using the SCAPS-1D code. We investigate how the photovoltaic parameters of the solar cell such as V_oc, J_sc, FF, and η are affected by varying the thickness of the absorber layer ranging from 1m to 2μm and bandgap value from 1 eV to 1.7 eV. Further, we demonstrate how the performance of this chalcopyrite material based solar cell varies with the increase in the temperature ranging from 300- 360K. By detailed understanding, we anticipate that an efficient CIGS solar cell can be developed in the future.

Here, we present two examples of strategies we have recently developed to elaborate ‘graphen-dye’ emitting platforms. In the first example, graphene and an emitting 3D building block are combined to obtain a light emitting graphene-based hybrid 2D system. We report the first fluorescent molecular self-assembly on graphene. The quenching of the fluorescence of the adsorbed dye by the adjacent graphene is hindered at the molecular scale based on a spacer approach, through a specifically designed dual-functionalized self-assembling building block. The resulting optical properties of the whole graphene−dye hybrid system are characterized by absorption and fluorescence spectroscopies. The second example deals with surface-confined host–guest chemistry in order to trap a functional 3D building block (3D Zn-Phthalocyanine complex) into a large 2D nanoporous template. Results on graphene with a 3D functional complex incorporating an emitter will be presented.

Fourier multispectral filtering is an attractive means to acquire an approximation of full spectral signal with very few measurements. In our previous work, we demonstrated this technique using photodetectors fabricated in-house using a single dielectric thin film as a Fabry-Perot sinusoidal filter. The main disadvantage of such filters is the design trade-off between the oscillation amplitude and the purity of the sinusoidal transmission spectrum. In this work we demonstrate a more attractive technique using liquid crystals (LCs). The birefringence response of the LCs naturally lends itself to a nearly perfect sinusoidal transmission function with high contrast, ideally oscillating between a transmission of 0% and 100%. Furthermore, the period of oscillations can be controlled by the applied voltage, making it possible to continuously tune the transmission spectrum and acquire a high resolution spectrum of the target signal. Our design consists of 16 custom photodetectors integrated with individually-addressable LC pixels. The whole system can be integrated onto a single-chip and enable high resolution spectroscopy capability in portable electronics.

A new and exciting imaging technique being applied to thin films, nanocoatings, nanogels, and nanoparticle analysis is ultra-low accelerating voltage or ultra-low-landing-energy scanning electron microscopy (ULVSEM). Instrument conditions in this mode are different than with typical SEM observation or contemporary low accelerating voltage (LVSEM) imaging. Hence, the images appear far different due to reduced beam penetration. The landing energy of the primary electron beam can be much lower than LVSEM, it can be reduced to far below 500 electron volts (eV), even as low as 10 eV. Thus, the electron beam range and penetration are reduced tremendously with some unavoidable loss of spatial resolution. Surface details are enhanced, contrast might favorably change, and secondary electron (SE) edge enhancement or “blooming” contributing to measurement uncertainty is greatly reduced, potentially allowing for more precise and new measurements once this imaging mode is fully characterized and accurately modeled. High-resolution field-emission electron sources, improved lens, detector designs, and sample biasing all contribute to the ability to image at such low electron landing energies. The techniques of ULVSEM are discussed, and an application example is presented.

Directed high-speed motion of nanoscale objects in fluids can have a wide range of applications. However, directed movement and high speed in the nanoscale are rarely compatible. Light is a convenient source that can drive nano objects to move by applying optical forces, but they are too weak to enable fast-moving swimmers in fluids. Here, we report ballistic plasmonic Au nanoparticle (NP) swimmers with unprecedented speeds (~397,000 um s-1) realized by not only optical pushing but also pulling forces from a single Gaussian laser beam. The Au NP excited by the laser at the surface plasmon resonance (SPR) peak interact with the NP both thermally and optically, leading unique conditions for ballistic movements and “negative” optical forces. The demonstrated ultra-fast, light-driven NP movement may lead to a wide range of nano- and bio-applications and provide new insights to the “negative” optical forces and nano-object manipulation.

We analyzed and proposed a planar plasmonic absorber based on a tri-layer nanorressonators structure using metal-PCM's-metal. The planar absorber uses resonance between the metal and dielectric layers, for maximum light absorption in the infrared (1000 – 2200nm) electromagnetic spectrum. The resonance peak of the absorber can be shifted to other regions of the spectrum by varying the phase (amorphous and crystalline) of the dielectric film. It is also possible to control the absorption with the angle of incidence in the TE and TM polarization modes. The high absorption and high tolerance for fabrication errors of the absorber proposed can be exploited in a large number of optoelectronic devices.

Beyond the eponymous snow slides, avalanching processes – where a compounding nonlinear cascade of events is triggered by a small perturbation – are found today in a surprising variety of phenomena including the popping of champagne bubbles, nuclear explosions, lasing, neuronal networking, and even financial crises. In optics, photon avalanching (PA) behavior garnered significant interest more than three decades ago as a method for achieving efficient upcoverted lasing, and, due to its extreme nonlinearity, was more recently proposed as a mechanism for realizing facile superresolution imaging if satisfactory nanomaterials could be designed. However, a demanding set of criteria has limited PA in Ln-based systems only to fragile bulk materials and aggregates, and mostly to cryogenic temperatures. Here, we have leveraged a combination of advanced theoretical modeling, synthesis, and photophysical characterization to create robust photon avalanching nanoparticles.

One of the main challenges for any applications of nanoparticles in biological media is to control the surface chemistry of the nanomaterials preventing chemical disintegration and agglomeration. When the surface effects dominate over the bulk properties, which is especially the case for small lanthanide doped NaYF4 nanocrystals, the surface capping significantly affects the brightness of the upconversion luminescence. Here, we present the influence of commonly used buffer systems such as N-(2-hydroxyethyl)piperazine-N’-(2-ethanesulfonic acid) (HEPES) and 2-(N morpholino)ethanesulfonic acid hydrate (MES) on the stability and surface chemistry of NaYF4:Yb,Er nanoparticles. The results indicate that surface modifications by ligand exchange provide a simple strategy for attaching many different ligands to the particle surface and render them water dispersible. Nevertheless, one has to take into account that particle surfaces are not fully covered and certain buffers, especially those with sulfo groups, may alter the surface chemistry with time.

We demonstrate the broadband visible luminescence from bulk crystalline silicon and silicon nanoparticles sized 100- 30 nm under near-infrared excitation. We show that the luminescence spectrum has two distinct peaks. The first being centered at 550 nm while the second appears close to the wavelength of the second harmonic of the excitation light. The appearance of the second peak is a signature of the highly athermal electron distribution never observed previously. The luminescence intensity and spectral shape strongly depend on the doping type and concentration. Despite being nonresonant, silicon nanoparticles enhance luminescence intensity when placed atop the silicon wafer. The observed phenomenon can be used for wafer inspection and defect detection, as well as for the creation of novel nanosources of light.

The ability to measure pH on a cellular scale has a wide range of potential use in biology and medicine. In this paper, we describe our work on creating a nanoscale pH sensor via the conjugation of upconverting nanoparticles (UCNPs) with a fluorescent dye. We will the explain the origin of the optical pH sensitivity, the conjugation procedure, as well as the various measurement techniques used to confirm the sensitivity. These nanoparticles allow simple optical sensing of pH without complicated intensity calibration process and could thus be widely applicable to many complex biological systems.

Photon upconversion, the process of converting lower-energy light to higher-energy, has attracted a lot of attention in biological applications, like phototherapy and bio-imaging. Among different photon upconversion mechanisms, triplet−triplet annihilation (TTA) based photon upconversion enables this process at low incident excitation power. Recently, I reported a 7% upconversion quantum yield with nontoxic and earth-abundant silicon nanocrystals as photosensitizer. However, ambient oxygen is an obstacle in further applications of photon upconversion as the triplet excitons involved in TTA can be quenched by oxygen in the air. Here, we discuss an air-stable photon upconversion system with silicon nanocrystals as sensitizer to upconvert red/green light to violet light. This hydrophobic silicon-based system has been incorporated into the aqueous phase with size-tunable micelles to enable applications in the water. An 11% photon upconversion quantum yield in micelles is achieved.

Upconversion materials have attracted much interest for biomedical applications. However, a wide-spread use requires a much improved upconversion efficiency for which plasmonic nanostructures offer a highly promising route. This paper presents the latest development in plasmonic nanostructures coupled with upconversion nanoparticles (UCNPs). First, a demonstration of over 1000x enhancement using a metal-insulator-metal architecture will be presented. Additionally, UCNP-gold nanostructure was conjugated with antibody to epidermal growth factor to target bladder cancer cells. We have demonstrated highly selective cell killing by optoporation-aided chemotherapy.

In order to overcome the low quantum yield of upconversion nanoparticles (UCNPs), plasmonic nanostructures have been used due to their strongly modified local E-field. However, the complex nature of plasmon-upconversion interaction by field enhancement and luminescence quenching is not well appreciated in general. Here, we present a spectroscopic study on the interaction between NaYF4:Yb3+,Er3+ UCNPs and gold nanostructures. The luminescence is monitored as the nanostructure geometry is varied. The interplay between the positive effect of local field enhancement and the negative effect of luminescence quenching is carefully analyzed by numerical simulations and rate equation analysis.

I will present an overview of our recent work on structural color printing using plasmonic resonances, dielectric nanoantennas, and photonic crystals. Using a wide range of materials from metals to dielectrics and nanostructuring them with tools such as electron beam lithography and two-photon photopolymerization lithography results in interesting light-matter interactions. In addition to generating colors these techniques have allowed simultaneous phase control for multi-color holography, with promising applications in anti-counterfeiting, optical data archival, and spectral selective detectors.

Improved 3D nanofabrication approaches could enable higher performance photonic devices. Existing approaches are limited in resolution, material compatibility, and/or the ability to fabricate complex geometries. Optical tweezers are attractive due to their ability to trap and position nanoscale objects of various materials with high precision. However, it is challenging to develop an automated platform that is robust and high-speed enough for rapid prototyping. Here we present such a system, discuss its positioning accuracy and speed, and, as a proof-of-concept, use it to assemble a light-guiding chain composed of biochemically functionalized 110 nm gold-silica nanoshells connected to a fluorescent nanoparticle.

Ultrafast telecommunications, computing, data processing, and sensing are critical to meeting the demands of modern and next generation networking, data transmission, and communications. Hybrid organic electro-optic (OEO) systems enable high-speed, energy-efficient, chip integrated solutions that significantly surpass the SWaP-CP of incumbent material technologies. Current technology infrastructure is facing constraints in computing speed, network capacity, and power efficiency while OEO materials integrated on-chip offer a scalable, market-transforming solution that enables “more than Moore” growth. Recent research milestones demonstrate OEO materials integrated into nanoscale waveguides, yielding > 500 GHz EO bandwidth, power consumption < 100 aJ/bit, and device footprints < 10 μm2. This performance has the potential to transform computing, enable ultrafast digital signal processing, 5G+ telecommunications, sensing, and electromagnetic interference (EMI/EMP) resilience. Key to enabling such commercial and governmental applications is the efficient processing of the materials when integrating into devices at large scale. In addition, materials must meet standard requirements for stability when exposed to varied environmental conditions including heat, humidity, and cold shock. Herein we describe recent results on the reliability of commercially available OEO materials. We also present a plan for these materials to be integrated into SOH and POH devices, and processed using existing commercial semiconductor and photonics foundry infrastructure. With these recent results demonstrating promising environmental stability, OEO materials are poised to be integrated into commercial SOH and POH devices at scale.

Failure of human body organs is believed to be one of the most important health problems all over the world. The application of stem cells in human regenerative medicine could be an alternative to organ transplantation, avoiding the problem of donor shortage and rejection. As few of the current treatment methods result in successful repair of damaged liver, the development of new procedures are warranted. The most recent type of liver regeneration approach is cell based therapy. The application of stem cell technology is gaining interest to be used for hepatic tissue engineering since stem cells have high proliferative capacity and multi-lineage differentiation potential. Stem cell-based therapy has received attention as a possible alternative to organ transplantation, owing to the ability of stem cells to repopulate and differentiate at the engrafted site. Advancements in the fields of stem cell biology and biomaterials science and engineering had been combined to produce strategies by which stem cell attachment; proliferation and differentiation in vitro were supported and enhanced. Before transplantation, cells were generally seeded on innovative modality of Nano scaffolds fabricated by electrospinning technique that recapitulate the extracellular matrix and provide cells with information that is important for tissue development. In this paper, we offer our view on the applying nanotechnology and present current and emergent approach in the field of hepatic tissue engineering for specific application. The application of nanotechnology to stem cell biology would be able to address the challenges of the failure of injected cells to engraft to target tissues.

Hybrid plasmonic substrates fabricated by a gap-controlled, template-assisted self assembly of plasmonic nanorods (NRs) inside plasmonic nanolines fabricated using large area lithography are presented. This fabrication process can potentially be employed for wafer scale fabrication of plasmonic substrates with sub-5 nm gaps. The electromagnetic hotspots arising due to these sub-5 nm gaps can be employed for sensing using surface enhanced Raman scattering (SERS). The gaps and the overall configurations of the hybrid substrate are dependent on a combination of several parameters such as the nanoline gaps and the size of the NRs assembled. These plasmonic substrates offer high electromagnetic enhancements along with the possibility of tuning the plasmon resonance wavelength in the near-IR region of the spectrum.

In this paper we analyze the relationship between the spatial frequency response of focused surface plasmon with the birefringence of the sample. The sample consists of thin film of photo-addressable azobenzene functionalized homopolymer. Due to the photoisomerization of the cis-trans relaxation states of azopolymer, anisotropy is induced in the sample and absorption pattern with ellipticity of 1.082 is observed at the exit pupil plane. Quantitative analysis of the ellipticity and orientation of the absorption pattern reveals the magnitude of birefringence and direction of fast axis of the sample. Simulated and experimental results are presented.

Driven by the strong need for cheap and integrable Si-based optoelectronic devices for a wide range of applications, continuing endeavors have been made to develop structures for light emission, modulation, and detection in this material system. Here, we report the realization of room-temperature stimulated emission in the technologically crucial 1.5 micron wavelength range from Er-doped GaN/AlN multiple-quantum wells on silicon and sapphire. Employing the well-acknowledged variable stripe technique, we have demonstrated an optical gain up to 170 cm^-1 in the multiple-quantum well structures. The observation of the stimulated emission is accompanied by the characteristic threshold behavior of emission intensity as a function of pump fluence, spectral linewidth narrowing and excitation length. The demonstration of room-temperature lasing at the minimum loss window of optical fibers and in the eye-safe wavelength region of 1.5 micron are highly sought-after for use in many applications including defense, industrial processing, communication, medicine, spectroscopy and imaging. As the synthesis of Er-doped GaN epitaxial layers on silicon and sapphire has been successfully demonstrated, the results laid the foundation for achieving hybrid GaN-Si lasers providing a new pathway towards full photonic integration for silicon optoelectronics.

Carbon-Titanium multilayer thin films were obtained by Thermionic Vacuum Arc (TVA) method. The nanostructured films consisting by 100nm Carbon base layer and seven 40nm alternatively Titanium and Carbon layers were deposed on Silicon substrate. As well, to give C-Ti multilayer films with different percentages in Ti and C of layers, a 100nm thick Carbon base layer was deposed on Si substrate, and then seven Ti-C layers, each of these having thickness of 40nm. In order to achieve the successively layers with C, and Ti different percentages, were adjusted the discharge parameters of C and Ti plasma sources to obtain the desired composition of layers. Also, were obtained composite films having a variable C: Ti atomic ratio 9:1 at interface to 1:9 at the surface. By changing of substrate temperature from room temperature to 100°C, 200°C, 300°C, 400°C respectively, and on the other hand the bias potential up to –700V, different batches of samples were obtained. Characterization of structural properties of films was achieved by Electron Microscopy technique (TEM, STEM) and GIXRD techniques. The measurements show that increase of the substrate temperature reveal changes in TixCy lattice parameters. Thus, according to GIXRD analysis it was found out that the Ti:C atomic ratio changes with increase of synthesis temperature. Also, in the case of composite films an increase of amount and sizes of TiC nanocrystals with the increase of energy of Ti ions determined by increase of bias voltage was observed. The tribological measurements were performed using a ball-on-disk system with normal forces of 0.5, 1, 2, 3N respectively. Was found that the coefficient of friction depends on the synthesis temperature and on the bias voltage. It is also noted that the friction coefficient depends on the pure C content, Ti content and amount of TiC nanocrystallites. These results are due to atomic diffusion at Ti/C interfaces and also are associated with amount of TiC nanocrystallites. To characterize the electrical conductive properties, the electrical surface resistance versus temperature have been measured, and then the electrical conductivity is calculated. Using the Wiedemann-Frantz law was obtained the thermal conductivity.

Magnetic field detection was experimentally demonstrated utilizing the optical spectral change of Al-subwavelength grating (SWG) on indium-tin-oxide (ITO) layer. The Al-SWG was fabricated on the ITO layer by electron-beam lithography technique. The fabricated sample shows the peak in the reflection spectrum resulting from the excitation of guided-mode in ITO layer. Electron accumulation layer in ITO was induced by applying magnetic field and flowing current, and the accumulation layer decreased the reflection peak intensity. As the magnetic field of 172 mT was applied, the intensity decreasing reached to 3 % of that without magnetic field. The intensity returned to the original value before measurement when the magnetic field and the current disappeared. These results indicate that our structure can detect tens of mT magnetic field without degaussing.

Optical components are the main parts in laser systems and also the limiting factor for high power laser. All-silica based optical components proved to have extremely high laser induced damage threshold and were already tested on standard glass substrates. Such coatings are fabricated by employing glancing angle deposition method, combination of nanostructured porous low refractive index and dense high refractive index thin films were fabricated. Anti-reflection coatings and mirrors with required reflection were achieved, which have superior LIDT values (50.7 J/cm²). Antireflection coating was deposited directly on BBO crystal and results are demonstrated. In this work, the possibility to improve microlaser systems with all-silica coatings is presented.

Birefringence behavior has been frequently obtained when subwavelength waveguides are used on devices construction. In order to explore this property, we analyze a tilted silicon-on-insulator periodically segmented waveguides (PSW). The propagation characteristics are analyzed for different values of duty cycle and tilt. The degree of the birefringence can be tailored only by changing SWGs structural parameters such as the grating period, the filling factor, and the tilting. Also the tilted PSW can works as a birefringent waveguide for both TE and TM modes polarization, an important and desired requisite in photonics circuit devices. The approach is easily adaptable to a wide range of waveguide dimension keeping the single-etch-step fabrication.

The work is devoted to the study of the optical properties of carbon nanoparticles synthesized by the method developed during our experimental studies. The optimal conditions for the creation of carbon nanostructures with predetermined properties are defined. Nanoparticles of the size of about 80-1020 nm created in our experimental approach, the maximum of absorption of which is localized at wavelengths is in the violet-blue region of the spectrum (420 nm) and the maximum of luminescence is in the green region (530 nm) are discussed. The size of carbon nanoparticles, using biological and atomic force microscopes, is measured. The absorption index at the wavelength of 633 nm, which is used for the diagnosis of optical speckle fields, is estimated. The assumption is made about the possibility of using the obtained particles for correlation diagnostics of optical speckle fields.

Paper contains results of investigation of nanosheets by modificated DLS technique. The modified method of dynamic light scattering is based on an additional estimation of complexity of the radiation scattered at different angles for the horizontal and vertical polarization of the input beam. It is shown that the complexity of the fluctuations of scattered field depend on the angle of scattering and polarization of the laser beam and allow us to qualitatively evaluate the sphericity of the particles. To quantify complexity, correlation exponent of fluctuations of the intensity of the field of scattered coherent optical radiation was used, respectively. Сorrelation exponent is determinated from the slope of the correlation integral. It was found that the slope of the correlation integral is not linear and depends on the sphericity of nanoparticles.

Synthesis of silver nanoparticles (AgNPs) with varied modifications of their surfaces helps to diversify and adjust nanoparticles for applying in new science areas. Complexes of antibiotics with AgNPs can be effective against resistant bacteria and become a sensitive tool for antibiotic-resistance mechanisms’ investigations. The main aim of the study was synthesized of AgNPs complexes with various antibiotics and study of their properties for application in investigation and overcoming of antibiotic-resistance mechanisms. Stable complexes of silver nanoparticles with ampicillin, cefotaxime, ceftriaxone, cefuroxime, chloramphenicol, ristomycin, teicoplanin and vanсomycin were obtained. The obtained nanoparticles were spherical with a size of 10-12 nm. The concentration of argentum in the final solutions was 55 μM, the concentration of antibiotic was 10 μM, except for vanсomycin and teicoplanin was 1 μM. The most stable in ethanol solution are the complexes of silver nanoparticles with teicoplanin, chloramphenicol and vanсomycin. The optimal storage temperature for teicoplanin, vanсomycin, ristomycin and chloramphenicol complex, is 4° C. The obtained complexes of antibiotics with AgNPs are more stable in alkaline media than in solutions with acidic pH. Bactericidal activity of all synthesized complexes of antibiotics with silver nanoparticles was higher in comparison with the corresponding solutions of antibiotics without nanoparticles.

Photonic crystals (PC) are structures with favorable propagation characteristic since they prohibit the passage of electromagnetic radiation in certain frequencies exhibiting photonic band gaps (PBG). In this work, the transmittivity of resonant cavities was analyzed in photonic crystal composed of crystals including defects. The simulation was based on the finite element method. The resulting transmittance was analyzed considering the effects of temperature on the photonic crystal cavity, thus, thermo-optical coefficients and thermal expansion coefficients of the materials used in the photonic crystal cavity were considered. As the temperature changes, a shift in the confinement of the modes to a specific wavelength is observed.

Block co-polymers (BCPs) enable large-scale patterning with nanoscale feature sizes. With high molecular weight BCPs, features and periods in the range 50 nm to 150 nm can be achieved. This feature size lends itself to sub-diffractive visible and near-infrared optical components. In this work, BCPs are used to form a triangular lattice on a glass surface; the lattice is selectively infiltrated with nickel oxide to produce a mask for plasma etching. The conical pillars formed by etching generate a gradual change of refractive index thus reducing the reflectivity of the glass surface over a broad range of wavelengths and angles.

We propose a facilitating model for optimization of waveguide crossing using particle swarm adapted method in conjunction with 2D finite elements to discover geometric configurations associated with the best transmission efficiency values. From a base structure, it was possible to generate optimal solutions by changing the geometric parameters of the initial structure. The change in the geometric characteristics of the structure could provide an enhancement of power transmission. The results of the simulations are presented and discussed to evaluate the performance of the proposed approach. We obtained efficiency values above 95%, showing that the chosen methodologies can be applied with great flexibility for other projects in the field of photonics. In addition, it is also possible to carry out projects with a greater number of waveguides.

We propose in this work a structure 3-D plasmonic absorber composed of metal-dielectric and ultrathin film layer of PCM's (Phase Changed Materials). The geometric parameters of the structure proposed were optimized to exhibits strong absorption for normal incidence. The effects of the phase change from PCM's are analyzed and it is possible to observe a shift in the resonant peaks of absorption when the phase changes from amorphous to crystalline. The geometrical parameters of the structure were analyzed so that the absorption peak was syntonized. Also analyzed the effects of the oblique incidence for the polarization modes TM and TE.

In this work, UHMWPE films with different additives were successfully fabricated via a combination of solvent-casting and unixial stretching technique at different draw ratio while fibers of high density polyethylene (HDPE) with silicon and oxide microcomposites were produced by melt-spinning consisting of twin-screw extrusion at various collection rates. The SEM images and DSC data showed the film structure becomes highly oriented along stretching direction and its melting temperature and crystallinity changes considerably by increasing the draw ratio, while the diameters of the fiber samples were reduced by increasing the fiber collecting speed and its crystallinity varies insignificantly with respect to the collecting speed. The optical properties of the polyethylene films and fibers were investigated in the long wave infrared (LWIR) spectral range.

This research reveals that the optical properties of hydrogenated a-Si can be modulated by varying chamber atmosphere of PE-CVD. When substrates temperature and chamber pressure were adjusted, the refractive index and the extinction coefficient was modulated. The highest refractive index at 450 nm is 4.3, and the lowest one is 2.6, which achieve 1.7 modulable indexes in the visible region. Also, this research provides lower than 0.1 extinction coefficient at the same wavelength. The lowest extinction coefficient can be applied to metasurfaces designs, and we propose 50%, and 85% conversion efficiency at 450 nm and 635 nm respectively. An experimental demonstration of these metasurfaces will be conducted.

The desorption of oxygen and carbon contamination are a key issue on improving the quantum efficiency of negative electron affinity GaAs-based photocathode during the preparation process. In this article, O-bonded and C-bonded absorption are executed in the calculation of pristine (100)-oriented GaAs photocathode of planar structure and nanowire structure. By analyzing the absorption energy, work function and dipole moments of different adsorption models, it is found that the adsorption of impurity atoms changed atomic and electronic structure of GaAs(100) pristine surface and affected the stability. The findings suggest that, oxygen impurities are more difficult to remove than carbon impurities due to more negative absorption energies especially in the surface layer. However, C-absorbed models may have bigger work function values than O-absorbed models in the most cases, which are not beneficial to the photoemission, and the phenomenon can be verified by the calculation results of surface dipole moments.

An ultra-compact 3D memristive atomic switch is co-integrated with a field-effect transistor (FET). The combined devices outperform similar state-of-the-art arrangements. The integrated transistor operates with an extremely sharp switching slope of below 3 mV/dec, low leakage below pA and a high current on/off ratio I_on/I_off < 10⁶. Moreover, our atomic switch features a < 10 ns switching and a < 300 mV operating voltage. Most importantly, the atomic switch has a small footprint of < 10 nm by 10 nm in line with the extreme feature size of the current FET technologies. Thus, this design could addresses the future needs of integrated circuits (ICs) for high integration density at low power consumption.

Optical sensors that utilize the evanescent field of an integrated waveguide are applied in a wide range of applications. Recently, evanescent field particle detectors based on dielectric strip waveguides were success- fully used for the detection of small particles (0 < 1 μm). We present optimizations of silicon nitride slab and strip waveguides based on numerical simulations, which maximize the evanescent field that interacts with the analyte such as particles. The fraction of the total light power that is transmitted in the evanes- cent region can be tuned by geometric parameters of the waveguide and the operation wavelength. We show that the optimum height of the slab waveguide scales linearly with the operation wavelength, which is in agreement with analytic results from literature. Moreover, linear correlations between the optimum waveguide geometry and wavelength could be derived for silicon nitride strip waveguides that are utilized for particle detection. The results for the optimum strip waveguide geometry are dependent on the target particle size. The derived geometries represent the optimum configuration for an evanescent field particle detector based on silicon nitride strip waveguides in order to exploit its full potential in terms of detection sensitivity. Enhanced sensitivities will be necessary to extend the detection range of evanescent field particle detectors down to small particles in the ultrafine regime (o≤ 100 nm).

The aim of the current work is to improve the response time of an optical readout based humidity sensor. Therefore, we present the application of nanoimprint lithography (NIL) on thin films which are deposited by initiated chemical vapor deposition (iCVD). Hydrogels are polymeric networks with the ability to swell after certain physical conditions change, which makes them very useful as sensing layers for optical devices. In the first step we used iCVD to deposit a humidity responsive hydrogel (here: pHEMA) as a planar thin film on sapphire substrates. To increase the effective surface area, we tried for the first time NIL on our hydrogel thin films with promising results: First, characterization with a SEM showed that NIL allows the design of large homogeneous areas of nanostructures without damaging the sensitive hydrogel thin film and having a great stability at ambient conditions. Second, NIL offers the benefit to build different geometries and sizes of nanostructures based on the requested application. For our first test we selected a simple line array structure, combined with an optical detection method as sensor principle. By choosing a specific structure to wavelength ratio the imprinted nanostructures act as a diffraction grating enabling a fast response time by increasing the effective sensing area. Since in our application the hydrogel works as the sensing element, we observed a humidity dependence behavior by measuring the intensity of the first order diffraction peak. Finally, the response time was a lot faster by using optical detection methods than commercial humidity sensors.

Photothermally generated surface microbubbles can build up high local concentration of solute near the bubble-surface interface. Since conventional surface-based biosensor systems inherently rely on the interaction of target analyte in a solution with surface-immobilized capture molecules, this concentrating phenomenon has a potential for improving sensor performance by breaking the diffusion-limited transport from bulk to surface. However, optical power and subsequent temperature for bubble generation should be alleviated due to thermal degradation of protein’s activity at above the boiling temperature of water. Here, we demonstrate that low-power photothermal generation of microbubbles can be realized by formulating volatile liquid droplets in the aqueous medium. This biphasic liquid system, wherein droplets on the plasmonic substrate undergo microbubble transformation upon light illumination, was able to induce Marangoni flow that concentrates proteins from bulk to the substrate.