This PDF file contains the front matter associated with SPIE Proceedings Volume 11998, including the Title Page, Copyright information, Table of Contents, and Conference Committee listings.

Organic light-emitting diodes (OLEDs) hold great promise as light sources for miniaturized and monolithically integrated optical sensors. Their unique properties and flexible processing methods enable the realization of disposable or recyclable lab-on-a-chip systems by combining multiple light sources and detector units on a single substrate. One of the main challenges in these systems is tailoring of light emission characteristics in order to illuminate specific sensing spots without the use of external optical components. Since OLEDs typically exhibit wide-angle light emission across the device surface, we propose the implementation of a nanostructured fluorescent waveguide. This layer acts as a color conversion filter by absorbing OLED light while providing narrow-angle emission of fluorescent light propagating in the waveguide. The appropriate choice of OLED emission color, fluorescent dye and nanostructure design allows for tailoring of the emission wavelength and beam characteristics. We investigate the impact of various fabrication parameters such as the layer thickness and fluorophore concentration on the color conversion efficiency as well as the directionality of the outcoupled fluorescent light. While high absorption of the OLED excitation light is beneficial in order to suppress wide-angle background emission, we show that high fluorophore content may lead to fluorescence quenching and reabsorption of fluorescent light inside the waveguide impairing resonant outcoupling effects.

A series of 2,7-disubstituted organogold(I) fluorenyls has been synthesized with full ground-state and optical characterization. Gold(I) is attached to the fluorenyl carbocycle through direct C–Au σ-bonds, or through intervening alkynyl linkages. The new complexes are dual fluorescence and phosphorescence emitters, leading in some cases, to apparent white light emission. Excited-state dynamics have been measured by ns and ultrafast transient absorption spectroscopy, and rate constants for radiative and nonradiative decay, and intersystem crossing, have been obtained. Both fluorescence and phosphorescence originate from metal-perturbed ligand-centric charge-transfer excited states. Compositions of the relevant frontier orbitals were calculated from density-functional theory.

Transition metal complexes have seen increased application in the fields of photoredox catalysis, photodynamic therapy, biological sensing, and as phosphors for organic light-emitting diodes. Additionally, non-linear optical applications of these materials have increased due to recent reports of two photon absorption and reverse saturable absorption (RSA) characteristics. Recent studies have demonstrated iridium is of particular interest as the transition metal center for organometallic chromophores because of its strong spin-orbit coupling, which allows for multiple excited states, thereby increasing the compound’s ability to absorb light over a broad spectrum. Our work focused on the synthesis of a series of functionalized phenylbenzothiazole (pbt) ligands to explore the effects on the photophysical properties of the synthesized Ir(III) cyclometalated chromophores and evaluate their potential application as RSA materials. The Ir(III) cyclometalated complexes were prepared from the bromo substituted pbt. The intermediate was then subjected to microwave assisted Suzuki reaction conditions to form the derivatized pbt cyclometalated complex.

Recently, cyclometalated iridium (III) complexes have been studied for use as non-linear optical (NLO) materials. Reports of both two photon absorption (2PA) and reverse saturable absorption (RSA) properties for cyclometalated iridium (III) complexes warrant their continued development for enhanced performance. Cyclometalating ligands used with iridium commonly ligate through an anionic carbon on a phenyl ring and a nitrogen on an adjacent ring, such as 2- phenylpyridine (ppy), 1-phenylpyrazole (ppz), 2-phenylbenzoxazole (pbo), and their derivatives. These ligands contain a rotational degree of freedom around the carbon-carbon bond that links the two rings. This flexibility could induce a nonradiative decay pathway in cyclometalated iridium complexes containing these ligands. Benzo[h]quinoline (bzq) was chosen as a more rigid, but structurally analogous, comparison to ppy. The complexes [Ir^III(ppy)₂(acac)]⁰ , [Ir^III(bzq)₂(acac)]⁰ , [Ir^III(ppy)₂(bpy)]PF₆, and [Ir^III(bzq)₂(bpy)]PF₆, where acac is acetylacetonate and bpy is 2,2’- bipyridine, were synthesized and characterized to assess the impact of enhanced cyclometalating rigidity in both neutral and charged iridium complexes. Through transient absorption spectroscopy, it was found that excited state localization and lifetime was drastically affected by the choice of either the acac or bpy ligand. Furthermore, the more rigid cyclometalating ligand, bzq, exhibited smaller non-radiative decay rates than the more flexible ppy analogue.

Dirhodium(II,II) complexes are shown to possess excited states accessible with visible to near-IR light that are able to undergo reactivity for applications ranging from photochemotherapy to solar energy conversion. In particular, cis– [Rh₂(DPhF)₂(bncn)₂]²⁺ (DPhF = N,N'-diphenylformamidinate, bncn = benzocinnoline; 1) is able to act as a single-molecule photocatalyst for the generation of hydrogen from acidic solutions in the presence of a sacrificial electron donor when irradiated with red/near-IR light. The water solubility of 1 led us to investigate its photoreactivity towards DNA. Complex 1 is able to photocleave DNA at pH = 5.3 upon irradiation with visible light, however, no photocleavage is observed at neutral pH. The binding of 1 to DNA was investigated and likely interacts with the polyanionic double helix through multiple modes, including electrostatic interactions, covalent coordination, and/or partial intercalation.

In the quest to reduce energy consumption, smart windows present a core solution to reduce the massive energy loss through windows. Smart windows can be designed on the basis of electrochromic (EC) principles, which offer simple integration mechanisms for color switching, optical sensing, energy harvesting, and energy storage. Photo-optical modulation of the EC window was explored using a thin film of polymer and a redox active electrolyte layer along with a dye-doped photoanode. The integrated photo-electrochromic window (PECW) showed high transparency over 78 % at bleached state but blocked 97 % of light at colored state. Furthermore, the PECW was capable of solar energy harvesting, allowing self-coloration under sunlight. The photo-optical modulation mechanism, material combination, and optimization of an autonomous PECW will be discussed.

We report on 3D bending detection via polymer optical fibers with eccentric Bragg-gratings. The concept relies on simple inscription of Bragg gratings in graded-index multimode polymer optical fibers with the phase mask method. When bending the flexible fibers, the lattice constant is varied and the Bragg peak changes. Bending is calculated from these shifts and the associated intensity change. Thus, the inscription of multiple gratings from three different angles at one position along the fibers allows the detection of bending and shape in 3D. In the next step, the sensor will be applied for movement detection of the human hand by integrating the functionalized polymer optical fibers into a sensor glove to monitor the bending of joints. This represents an interesting alternative to fiber optical sensors, as the polymer fibers are more cost-efficient and flexible compared to their glass-based counterparts. Further application for the detection of strain, temperature, humidity or concentration will be explored, potentially also in multiplexed settings.

A technology of co-packaged optics, which is mounting photonics integrated circuits and electronic integrated circuits on the same board, is essential to meet the demands of high-capacity transmission in data centers. In this respect, polymer optical waveguides have attracted much attention because of mechanical stability, excellent processability, and compatibility with electronic circuits. To achieve high-capacity optical transmission, we are developing a new package substrate, which we call active optical package (AOP) substrate, as a solution of co-packaged optics. The AOP substrate consists of a conventional organic package substrate such as glass-epoxy substrates, on which silicon photonics dies are embedded and SMF connectors are mounted. In the AOP, the silicon photonics inputs/outputs (I/Os) and the optical connectors are connected by 3D optical wiring technology that has a function of converting the pitch size. The 3D optical wiring is realized with a pair of micro-mirrors and a single-mode polymer waveguide.

First, we have evaluated the high-speed optical transmission performance of a single-mode polymer optical waveguide for LAN-WDM network. We observed there was no noticeable penalty for optical transmission for all LAN-WDM channels. And then, we demonstrate transmission of an AOP substrate comprising of silicon waveguide, two micro-mirrors and polymer waveguide. Transmission of 112-Gb/s PAM4 optical signal was performed without noticeable penalty up to 85 °C.

We report on a series of novel experimental results based on deoxyribonucleic acid (DNA)-biopolymer host/conductive nanoparticle guest composites and polymethylmethacrylate (PMMA)-amorphous polymer host/conductive nanoparticle guest composites. Surprisingly, the EMI shielding effectiveness measured ~40% higher using the DNA-based biopolymer host than those of the PMMA host. The comparison between the material processing, thin film fabrication and electromagnetic interference shielding effectiveness, using both types of host materials are presented.

In recent years, lossy mode resonance (LMR) biosensors have proven to be promising devices for the analysis of biological entities. In this work, for the first time, the possibility of observing the LMR effect in photonic integrated sensor based on SU-8 waveguides for biosensing applications is presented. SU-8 is a polymer that is ideally suited for optical waveguide applications due to its very high optical transparency, chemical stability and simple fabrication process. The LMR effect is achieved by using ZnO and TiO_x claddings over the waveguides. The influence of different cladding thicknesses and materials on the LMR effect is demonstrated. Different design waveguides are tested. Potential future applications and development steps of integrated LMR sensor will be discussed.

Hybrid organic electro-optic (OEO) modulators consist of a layer of ordered organic chromophores confined between layers of metals or semiconductors, enabling optical fields to be tightly confined within the OEO material. The combination of tight confinement with the high electro-optic (EO) performance of state-of-the-art OEO materials enables extraordinary EO modulation performance in silicon-organic hybrid (SOH) and plasmonic-organic hybrid (POH) device architectures. Recent records in POH devices include bandwidths >500 GHz and energy efficiency <100 aJ/bit. To enable commercial applications of these materials and devices, however, they must withstand demanding thermal and environmental conditions, both during manufacture and operation. To address these concerns, we examined the long-term thermal and environmental shelf storage stability of state-of-the-art commercial and developmental OEO materials under a variety of conditions relevant to Telecordia GR-468-CORE standards. We examined the shelf storage of poled OEO materials under a nitrogen atmosphere at a range of temperatures from 85 ˚C up to 150 ˚C to understand the kinetics of the thermally activated de-poling of the OEO materials. We also examined the shelf storage of OEO materials under a variety of atmospheres, including the aggressive 85 ˚C and 85% relative humidity damp heat condition, to understand the relative sensitivities of the materials to water and oxygen at different temperatures. We analyze the results of these studies and discuss their implications for commercial application of these materials and devices, including manufacturing, encapsulation requirements, and expected operational lifetimes.

Polarization-sensitive media based on polymers and functional chromophores have deservedly occupied their niche among photonic materials that are increasingly contributing to the possibilities of richer light sensing, in the field of optical communications, information transfer, its storage, display, etc. within a wide range of applications. The media considered here are represented by multiple highly polar compositions based on functional azo dyes doped in a compatible biopolymer as a matrix. This paper presents our specific studies on the influence of molecular-structural factors on the photoanisotropic properties of polarization-sensitive compositions. The illustrative examples show evidence of the finding of one of the factors that work out the light sensitivity of the materials for multiple times. This factor was the molecular aggregation of the chromophoric component. Quite accurate comparisons are shown of the improvement in photoresponsibility of various compositions with the mutual combination of their chromophoric molecules, in particular as a result of their component dimerization. In the overwhelming majority of azochromophoric dimers demonstrate greater sensitivity to actinic polarized light rather than their predecessor versions. The paper also demonstrates an example of going beyond the framework of dimerization towards the further development of the aggregation of molecules with the formation of azopolymers. The latter turned out to be promising in the case of the correct implementation of increasing integration of the components of the studied materials.

Structural design and characterization of fluorescent/phosphorescent multilayer top-emitting organic light-emitting diode (OLED) are investigated numerically with the Advanced Physical Model of Semiconductor Devices (APSYS) simulation program in this work. Specifically, the carrier balance and control of the migration of the triplet exciton diffusion avoiding the serious quenching which contributes to the roll-off in quantum efficiency at high current density, and limiting the singlet and triplet excitons at a better emitting zone can be optimized with appropriate cavity design of top-emitting OLED structure. Comparison between the results obtained numerically in this investigation and those obtained experimentally is made. Optimization of the optical and electronic performance of the multilayer OLED devices is attempted. The simulation results show that a better choice for the trade-off between color stability and electroluminescence efficiency can be achieved by properly adjusting the microcavity effect. An optimized performance is achieved if the recombination zone is designed to be located at the maximum of relative power, i.e., the anti-nodal region of the standing wave.

The structure of the receptive fields of simple cells in the visual cortex can be approximated by the Gabor function, defined as the product of a Gaussian function and a sine wave. We aim to study the mechanism of visual information processing in organisms based on a constructive method utilizing the fabrication of an artificial receptive field using a kind of protein. Bacteriorhodopsin (bR) is a retinal protein that composes the cell membrane of halophilic bacteria and resembles the human visual pigment rhodopsin. BR nano-ink was printed in the shape of a Gabor function on two transparent electrodes by a material printer to produce a Gabor filter that mimics the simple cell receptive field. The café wall illusion was detected using this artificial receptive field, and the results were compared with the simulation results.