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This paper describes the design, fabrication, and record performance of a new class of ultra-wideband wavelength tuning, ultra-low noise semiconductor laser, the Integrated Coherent Tunable Laser (ICTL). The ICTL device is designed for, and fabricated in, a CMOS foundry based Silicon Photonics platform, utilizing heterogeneous integration of III-V material to create the integrated gain section of the laser - enabling high-volume mass-market manufacturing at low cost and with high reliability. The ICTL incorporates three or more ultra-low loss micro-ring resonators, with large ring size, in a Sagnac loop reflector geometry, creating exceptional laser reflector performance, plus an extended laser cavity length that enables highly-coherent output; ultra-low linewidth and phase noise. This paper describes record integrated laser performance; 118 nm wavelength tuning, covering S-, C- and L-bands, with Lorentzian linewidth

The development of low-cost materials for charge-selective contacts that provide good energetic alignment with perovskite active layers, favorable thermal properties, and lead to efficient photocon...

In this work, we demonstrate for the first time the design and fabrication of microchip electrophoresis devices containing cross-shaped channels and spiral electrodes around the separation channel for microchip electrophoresis and capacitively coupled contactless conductivity detection. The whole device was prepared in a digital light processing-based 3D printer in poly(ethylene glycol) diacrylate resin. Outstanding X-Y resolution of the customized 3D printer ensured the fabrication of 40-μm cross section channels. The spiral channels were filled with melted gallium to form conductive electrodes around the separation channel. We demonstrate the applicability of the device on the separation of sodium, potassium, and lithium cations by microchip electrophoresis. Graphical abstract.

Among all the contributions made by Mark Stockman, his work on concentrating the light energy to unprecedented densities is one of the most remarkable achievements. Here it is briefly reviewed and a relatively novel, intuitive, and physically transparent interpretation of nanofocusing using the effective volume of hybrid coupled modes formalism is presented and the role of Landau damping as the main limiting factor is highlighted.

Densely integrated active photonics is key for next generation on-chip networks for addressing both footprint and energy budget concerns. However, the weak light-matter interaction in traditional active Silicon optoelectronics mandates rather sizable device lengths. The ideal active material choice should avail high index modulation while being easily integrated into Silicon photonics platforms. Indium tin oxide (ITO) offers such functionalities and has shown promising modulation capacity recently. Interestingly, the nanometer-thin unity-strong index modulation of ITO synergistically combines the high group-index in hybrid plasmonic with nanoscale optical modes. Following this design paradigm, here, we demonstrate a spectrally broadband, GHz-fast Mach–Zehnder interferometric modulator, exhibiting a high efficiency signified by a miniscule VπL of 95 V μm, deploying a one-micrometer compact electrostatically tunable plasmonic phase-shifter, based on heterogeneously integrated ITO thin films into silicon photonics. Furthermore we show, that this device paradigm enables spectrally broadband operation across the entire telecommunication near infrared C-band. Such sub-wavelength short efficient and fast modulators monolithically integrated into Silicon platform open up new possibilities for high-density photonic circuitry, which is critical for high interconnect density of photonic neural networks or applications in GHz-fast optical phased-arrays, for example.

Graphene has emerged as an ultrafast photonic material for on-chip photodetection. However, its atomic thickness limits its interaction with guided optical modes, which in turn weakens the photoresponse of waveguide-integrated graphene photodetectors. Nonetheless, it is possible to enhance the interaction of guided light with graphene by nanophotonic means. Herein, we propose a practical design of a plasmon-enhanced photovoltaic double-graphene detector that is integrated into 5 $\mu$m long titanium nitride slot waveguides. The use of double-graphene in this configuration yields a high responsivity of 2.18 A/W and more for a 0.5 V bias, across the telecom C-band and beyond. Moreover, the device operates at an ultra-high-speed beyond 100 GHz with an ultra-low noise equivalent power of $pW/$\sqrt{\text{Hz}}$. The reported features are highly promising and are expected to serve the needs of next-generation optical interconnects.

Melt inclusions record the depth of magmatic processes, magma degassing paths, and volatile budgets of magmas. Extracting this information is a major challenge. It requires determining melt volatile contents at the time of entrapment when working with melt inclusions that have suffered post-entrapment modifications. Several processes decrease internal melt inclusion pressure, resulting in nucleation and growth of a vapor bubble and, time permitting, diffusion of volatiles (especially CO2) into the vapor bubble. Previous studies have shown how this process may lead to most of the CO2 in the bulk melt inclusion being lost to the bubble. Without reconstruction, most of the melt inclusion data in the literature vastly underestimate the CO2 concentrations of magmas by measuring the glass phase only. Methods exist that attempt to reconstruct the entrapped CO2 contents, but they can be difficult to apply and do not always yield consistent results. Here, we explore bubble growth, evaluate CO2 reconstruction approaches, and develop improved experimental and computational approaches. Piston-cylinder experiments were conducted on olivine-hosted melt inclusions from Seguam (Alaska, U.S.A.) and Fuego (Guatemala) volcanoes at the following conditions: 500–800 MPa, 1140–1200 °C for Seguam and 1110–1140 °C for Fuego, 4–8 wt% H2O in the KBr brine filling the experimental capsules, and run durations of 10–120 min. Heated melt inclusions form well-defined S-CO2 trends consistent with degassing models. CO2 contents are enriched by a factor of ~2.5, on average, relative to those of the glasses in unheated melt inclusions, whereas S contents of heated and unheated melt inclusion glasses overlap, indicating that insignificant amounts of S partition into the vapor bubble. For naturally quenched melt inclusions, relatively low closure temperatures for CO2 diffusion enables some CO2 to enter vapor bubbles during quench, whereas higher closure temperatures for S diffusion limits its loss to vapor bubbles. We evaluate the timescales of post-entrapment processes and use the results to develop a new computational model to restore entrapped CO2 contents: melt inclusion modification corrections (MIMiC). Heated melt inclusion data are used as a benchmark to evaluate the results from MIMiC and other published methods of CO2 reconstruction. The methods perform variably well. Key advantages to our experimental technique are accurate measurements of CO2 contents and efficient rehomogenization of large quantities of melt inclusions. Our new computational model produces more accurate results than other computational methods, has similar accuracy to the Raman method of CO2 reconstruction in cases where Raman can be applied (i.e., no C-bearing phases in the bubble), and can be applied to the vast body of published melt inclusion data. To obtain the most robust data on bubble-bearing melt inclusions, we recommend taking both experimental- and MIMiC-based approaches.

Metasurfaces are two-dimensional patterns that are used to manipulate the propagation of light by controlling the resultant transmittance, reflectance, or absorption at specific wavelengths. Metasu...

Up-conversion photoluminescence (UCPL) refers to the elementary process where low-energy photons are converted into high-energy ones via consecutive interactions inside a medium. When additional energy is provided by internal thermal energy in the form of lattice vibrations (phonons), the process is called phonon-assisted UCPL. Here, we report the exceptionally large phonon-assisted energy gain of up to ~ 8kBT (kB is Boltzmann constant, T is temperature) on all-inorganic lead halide perovskite semiconductor colloidal nanocrystals that goes beyond the maximum capability of only harvesting optical phonon modes. By systematic optical study in combination with a statistical probability model, we explained the nontrivial phonon-assisted UCPL process in perovskites nanocrystals, where in addition to the strong electron-phonon (light-matter) coupling, other nonlinear processes such as phonon-phonon (matter-matter) interaction also effectively boost the up-conversion efficiency. Ministry of Education (MOE) National Research Foundation (NRF) Accepted version Q. X. gratefully acknowledges financial support from the Singapore National Research Foundation through the NRF Investigatorship Award (No. NRF-NRFI2015-03) and the Singapore Ministry of Education via AcRF Tier 3 Programme (No. MOE2018-T3-1-002), Tier 2 grant (No. MOE2018-T2-2-068)and Tier 1 grants (Nos. RG103/15 and RG113/16). A. G. D. A. gratefully acknowledges the financial support of the Presidential Postdoctoral Fellowship program of the Nanyang Technological University. We acknowledge Dr. Lulu Zhang for his help on the TEM characterization.

Plasmon-assisted hot carrier processes in metal nanoparticles can be described either classically or using the full strength of quantum mechanics. We reconfirm that from the practical applications point of view, when it comes to description of the decay of plasmons in nanoparticles, classical description is sufficiently adequate for all but the smallest of the nanoparticles. At the same time, the electron temperature rise in nanoparticles is discrete (quantized) and neglecting this fact can lead to significant underestimating of hot carrier assisted effects, such as photocatalysis.

We propose an ultrafast on-chip CMOS compatible graphene plasmonic photodetector based on the photothermoelectric effect (PTE) that occurs across an entire homogeneous graphene channel and operatin...

Ultrafast processes occurring on nanoscale surfaces can be probed with ultrafast low-energy electron pulses. Specifically, for metallic samples, the interaction of free electrons with surface plasmon fields provides insight into the nanoscale electron dynamics at the surface. Current models and experiments include the interaction of electrons with the sample, but ignore electron–electron and electron–plasmon interactions. Here we show that secondary electrons and their interaction with the incident primary electrons via nonrelativistic Moller scattering in the presence of optical and surface plasmon fields significantly alters the electron dynamics probed with ultrafast low-energy electron microscopy. Modeling this electron–plasmon interaction is key for interpreting ultrafast electron dynamics on metallic surfaces. Ultrafast electron microscopy can be used to analyse transient phases of a system, and understanding the various electron-electron interactions are key to interpreting the data. Here, the authors investigate the mechanisms behind free electron-plasmon interactions and their contribution to ultrafast electron dynamics at metallic surfaces.

Excessive flooding of the built-up territories in the areas of permafrost soils often occurs due to changes in natural factors (including climatic) or design deficiencies and can negatively affect frozen soils for a long time. Currently, there is no complete methodology for calculating this effect. The solution to this problem is closely related to clarifying the nature of the formation of temperature shift, which at the moment is not clear enough. The aim of the work is to create a methodology for predicting changes in soil temperature in the event of a shallow reservoir on its surface In the first part of the article, the simplest theoretical model of the phenomenon of temperature shift is proposed, on the basis of which fairly convenient analytical expressions are obtained for the average annual temperature at the bottom of the active layer, depending on climatic factors and soil properties. The model most clearly demonstrates the nature of the occurrence of the phenomenon and can be used for simple assessments, as well as in the educational process. In particular, it is demonstrated that the magnitude of the shift is caused not only by the difference in the thermophysical characteristics of thawed and frozen soil, but also by the asymmetry of climatic parameters. In the second part of the article, using the quasistationary methods, calculations of the predicted temperature of the soil when a reservoir of a given depth on its surface occurs. Unlike previously used methods, the predicted parameters of the soil are counted from its unperturbed state, which is determined by the authors previously proposed method, which allows us to evaluate the direction of the changes (towards cooling or warming). It is shown that the influence of a shallow (up to a meter deep) surface water body on the temperature of frozen soils substantially depends on the process of mixing water in the summer. For the first time, the direction of these processes has been established: with a high degree of mixing, the influence is always warming and grows with the depth of the reservoir; in the absence of mixing, the pond cools the base at shallow depths, and with an increase in depth above a certain value, an warming effect occurs, which, however, is much lower than in the presence of mixing. The practical applications of the results are considered.

Graphene has emerged as an ultrafast photonic material for on-chip all-optical switching applications. However, its atomic thickness limits its interaction with guided optical modes, resulting in a high switching energy per bit. Herein, we propose a novel technique to electrically control the switching energy of an all-optical graphene switch on a silicon nitride waveguide. Using this technique, we theoretically demonstrate a 120 µm long all-optical graphene switch with an 8.9 dB extinction ratio, 2.4 dB insertion loss, a switching time of ∼ 16 × . This technique paves the way for the emergence of ultra-efficient all-optical graphene switches that will meet the energy demands of next-generation photonic computing systems, and it is a promising alternative to lossy plasmon-enhanced devices.

Biofouling disrupts the surface functionality and integrity of engineered substrates. A variety of natural materials such as plant leaves and insect wings have evolved sophisticated physical mechanisms capable of preventing biofouling. Over the past decade, several reports have pinpointed nanoscale surface topography as an important regulator of surface adhesion and growth of bacteria. Although artificial nanoengineered features have been used to create bactericidal materials that kill adhered bacteria, functional surfaces capable of synergistically providing antiadhesion and bactericidal properties remain to be developed. Furthermore, fundamental questions pertaining to the need for intrinsic hydrophobicity to achieve bactericidal performance and the role of structure length scale (nano vs micro) are still being explored. Here, we demonstrate highly scalable, cost-effective, and efficient nanoengineered multifunctional surfaces that possess both antiadhesion and bactericidal properties on industrially relevant copper (Cu) and aluminum (Al) substrates. We characterize antiadhesion and bactericidal performance using a combination of scanning electron microscopy (SEM), atomic force microscopy (AFM), live/dead bacterial staining and imaging, as well as solution-phase and Petrifilm measurements of bacterial viability. Our results showed that nanostructures created on both Cu and Al were capable of physical deformation of adhered

Epsilon-near-zero (ENZ) materials have been key players in recent photonic applications due to their versatility in growth, excellent compatibility, and ability to be dynamically modulated. From a foundation in the recently developed carrier kinetic models of nonlinearities in ENZ materials, we discuss our efforts to realize scalable and high-quality Al:ZnO (AZO) films via a unique atomic layer deposition (ALD) process, and the use of AZO in both switching and frequency shifting applications. Throughout, we highlight the advantages and challenges that exist and conclude with an outlook for ENZ materials in the area of nonlinear optics.

Two-dimensional layered materials (2DLMs) have been extensively studied in a variety of planar optoelectronic devices. Three-dimensional (3D) optoelectronic structures offer unique advantages inclu...

Protein biomaterials have been used for a wide range biomedical applications due to their intrinsic biocompatibility, versatility and higher order structure. Multifunctional theranostic agents fabricated by incorporating the diagnostic modalities and drug payloads in protein nanoformulations have garnered significant attention in recent years. Protein-based theranostic agents manifest high target specificity, enhanced blood circulation and reduce reticuloendothelial system elimination. This review focuses on the fabrication of peptide- and protein-based nanoformulations for imaging guided therapy.

The need for faster and more accurate manufacturing methods for composite parts continues to grow. Co-curing composite structures can decrease manufacturing time by eliminating secondary operations such as grinding, jigging, bonding, and fastening while creating lighter and more accurate parts. As a demonstrator for co-curing techniques, a six-meter carbon fiber wing for a high-altitude and high-speed dynamically soaring unmanned aerial vehicle (UAV) was designed and manufactured in one cure cycle. Two wing-skin molds were created using low density tooling board, with the mold geometry directly machined into the material, reducing tool manufacturing time and cost. An aluminum insert was used to create a trailing edge cavity while maintaining a simple parting line of the wing tool. Three removable forms made of polystyrene foam inside of the wing cavity were used to position six internal webs and, after curing and removal of the forms, resulted in a hollow wing with internal webs. The resulting wings showed some defects in the wing skins but overall produced structurally sound parts. The method shows great potential for creating complex composite parts using only a single cure cycle with little finishing work and no secondary bonding, resulting in high precision at a relatively low cost.

Silicon Photonics foundry based Integrated Coherent Tunable Laser (ICTL) devices display record performance; 118 nm wavelength tuning covering S-, C- and L-bands, Lorentzian linewidths below 100 Hz, and –155 dBc/Hz relative intensity noise.

We appraise a waveguide-integrated plasmonic graphene photodetector based on the hot carrier photo-bolometric effect, with performance characterized simultaneously by high responsivity, on the scale of hundreds of AW-1, and high speed on the scale of 100s of GHz. Performance evaluation is based on a theory of bolometric effect originating from the band nonparabolicity of graphene. Results compare favorably with the state-of-the-art plasmonic bolometric photodetectors, predicting up to two orders of magnitude increase in a responsivity while keeping speed on the same level, defined by the electron-lattice scattering time in graphene., Comment: 18 pages, 9 figures. arXiv admin note: text overlap with arXiv:2002.04061

Metal-based nanostructures made from low-loss plasmonic materials allow a targeted and strong enhancement of light-matter interaction in a broad wavelength range. As a result, the far-field single-photon emission rates from solid-state quantum defects can overcome both the rate of dipole dephasing and that of plasmon absorption in metals. This approach promises the advent of single-photon sources featuring bitrates up to the THz range and operating at cryogen-free temperatures. We establish simple and intuitive fundamental enhancement limits for plasmonic systems coupled to quantum emitters and present practical methods for achieving these advantageous regimes.

Nanoimprinting lithography (NIL) is a next-generation nanofabrication method, capable of replicating nanostructures from original master surfaces. Here, we develop highly scalable, simple, and nondestructive NIL using a dissolvable template. Termed dissolvable template nanoimprinting lithography (DT-NIL), our method utilizes an economic thermoplastic resin to fabricate nanoimprinting templates, which can be easily dissolved in simple organic solvents. We used the DT-NIL method to replicate cicada wings which have surface nanofeatures of ∼100 nm in height. The master, template, and replica surfaces showed a >∼94% similarity based on the measured diameter and height of the nanofeatures. The versatility of DT-NIL was also demonstrated with the replication of re-entrant, multiscale, and hierarchical features on fly wings, as well as hard silicon wafer-based artificial nanostructures. The DT-NIL method can be performed under ambient conditions with inexpensive materials and equipment. Our work opens the door to opportunities for economical and high-throughput nanofabrication processes.

We study experimentally the effect of oxide removal on the sub-bandgap photodetection in silicon waveguides at the telecom wavelength regime. Depassivating the device allows for the enhancement of the quantum efficiency by about 2–3 times. Furthermore, the propagation loss within the device is significantly reduced by the oxide removal. Measuring the device 60 days after the depassivation shows slight differences. We provide a possible explanation for these observations. Clearly, passivation and depassivation play an essential role in the design and the implementation of such sub-bandgap photodetector devices for applications such as on-chip light monitoring.

It was recently demonstrated in the experiments [1,2] that the internal photoemission efficiency can reach several tens of percents because of "coherent" or, "surface" photoemission. In present work we provide theoretical description of this effect assuming the surface photoemissionin the structureconsisting ofthe Schottky-barrier metal-semiconductor interface with the Quantum Well (QW) inside. We take into account the difference of dielectric permittivities for the metal and the semiconductor which strongly affects the photoemission efficiency. We show that QW inside the Schottky-barrier can lead to (a) lowering the threshold energy of the photoemission due to resonance tunneling of electrons through the intermediate quasi-level of energy in QW; (b) the photoemission efficiency can be increased by several orders of magnitude.

High Power Semiconductor Radiation Balanced Laser (RBL) is an attractive proposition, however, both theoretical and experimental research has shown that fully balanced semiconductor RBL remains an elusive goal. At the same time, rare-earth doped materials have been successfully optically cooled. In this talk we present the investigation of tandem RBL consisting of semiconductor vertically emitting laser (VECSEL) that is cooled by a rare earth doped material in thermal contact with it and show that substantial power can be obtain in the radiation balanced regime.

We investigate a waveguide-integrated plasmonic graphene photodetector operating based on the hot carrier photo-bolometric effect, which is characterized simultaneously by high responsivity on the scale of hundreds of A/W and high speed on the scale of 100's of GHz that is limited only by the product of the electronic heat capacitance and thermal resistance. We develop a theory of the bolometric effect originating from the band nonparabolicity of graphene and estimate responsivity due to the bolometric effect, which is shown to significantly surpass the responsivity of the coexisting photoconductive effect, thus convincingly demonstrating the dominance of the bolometric effect. Based on the theory, we propose a novel detector configuration based on a hybrid waveguide that allows for efficient absorption in graphene over a short distance and subsequently a large change of conductivity. The results demonstrate the potential of graphene for high-speed communication systems.

We demonstrate the effective generation of singlet oxygen (1O2) catalyzed by hot electrons obtained from the plasmon decay in TiN@TiO2 core-shell nanoparticles at 700 nm excitation.

We investigate a waveguide-integrated plasmonic graphene photodetector operating based on the hot carrier either photo-thermoelectric or photo-bolometric effect, which is characterized simultaneously by high responsivity on the scale of hundreds of A/W and high speed on the scale of 100’s of GHz. The proposed detector configuration is based on a hybrid waveguide that allows for efficient absorption in graphene over a short distance and subsequently a large change of conductivity. The results demonstrate the potential of graphene for high-speed communication systems.

Plasmonic structures are known to support the modes with sub-wavelength volumes in which the field/matter interactions are greatly enhanced. Coupling between the molecular excitations and plasmons leading to the formation of “plexcitons” has been investigated for a number of organic molecules. However, plasmon-exciton coupling in metal/semiconductor structures has not experienced the same degree of attention. In this work, we show that the “very strong coupling” regime in which the Rabi energy exceeds the exciton binding energy is attainable in semiconductor-cladded plasmonic nanoparticles and leads to the formation of Wannier exciton-plasmon polariton (WEPP), which is bound to the metal nanoparticle and characterized by dramatically smaller (by a factor of a few) excitonic radius and correspondingly higher ionization energy. This higher ionization energy, which exceeding approaches 100 meV for the CdS/Ag structures, may make room-temperature Bose-Einstein condensation and polariton lasing in plasmonic/semiconductor structures possible.

Internal photoemission of charged carriers from metal to semiconductors plays an important role in diverse fields such as sub-bandgap photodetectors and catalysis. Typically, the quantum efficiency of this process is relatively low, posing a stringent limitation on its applicability. Here, we show that the efficiency of hot carrier injection from a metal into a semiconductor across a Schottky barrier can be enhanced by as much as an order of magnitude in the presence of surface roughness on the scale of a few atomic layers. Our results are obtained using a simple semianalytical theory and indicate that properly engineered plasmonic-assisted internal photoemission photodetectors can be a viable alternative in silicon photonics. Other applications, such as plasmonic-enhanced photocatalysis, can also benefit from these results.

An oil-in-water nanoemulsion capable of dispersing upconverting nanoparticles (UCNPs) for 7 months was investigated. Negative staining transmission electron microscopy shows that the UCNPs reside in the oil phase of the nanoemulsion. Dynamic light scattering measurements indicate that the majority of the oil volume is contained in droplets less than 1 μm in diameter. The system studied could be used to inkjet print UCNPs at least 7 months after the ink was first formulated. Nanoemulsion stability was tested in the short term, over 11 days, using an ink stability test developed for this research. It was found that after an initial loss of UCNPs, the majority of the UCNPs remained well-dispersed in solution. The UCNP dispersion was stable for longer periods under storage at 333 K compared to storage at 277 K.

Directional freeze-casting (FC) of powder suspensions followed by freeze-drying and sintering is a versatile and scalable processing route for creating metallic foams with highly elongated pores. Because of the high propensity for oxidation of metal powders, the use of precursor oxide powders is studied here with an additional step of H2-reduction of oxides to metal before sintering. However, the large volume shrinkage due to oxide reduction causes foam deformations, making it difficult to optimize the FC parameters to obtain a particular foam structure. We use quasi in situ X-ray microtomography to analyze the three-dimensional structural evolution of directionally freeze-cast, lamellar Fe2O3 and Fe2O3+NiO green bodies as they are reduced by H2 at 725 °C to Fe and Fe-20Ni (at%), respectively, and sintered at 900 °C. These temperature and gas conditions result in sequential reduction and sintering steps that can be individually analyzed. Foam porosity, pore width, lamellae thickness, and macroscopic shrinkage are quantified by image analysis. Oxide green body structures match typical FC relationships: porosity increases with decreasing powder content in the FC suspension, and the lamellae spacing period, or FC wavelength, decreases with increasing freezing velocity. Upon H2-reduction, lamellae in Fe foams buckle due to mismatch stresses from spatially-inhomogeneous reduction rates, leading to anisotropic deformation. Buckling is absent in Fe-20Ni foams due to the faster reduction kinetics of Ni/NiO that lead to more spatially uniform reduction. Reduction is responsible for 73–86% of the total volumetric shrinkage, with sintering causing the remaining shrinkage, which is nearly isotropic for all foams. The observed relationships between FC parameters, green body and metal foam structure can help guide the design and optimization of metal foams for specific technological applications.

Membranes that can separate compounds based on molecular properties can revolutionize the chemical and pharmaceutical industries. This study reports membranes capable of separating organic molecules of similar size based on their electrostatic charge. These membranes feature a network of carboxylate-functionalized 1-3 nm nanochannels, manufactured by a simple, scalable coating process: a porous support is coated with a packed array of polymer micelles in alcohol, formed by the self-assembly of a water-insoluble random copolymer with fluorinated and carboxyl functional repeat units. The interstices between these micelles serve as charged nanochannels through which water and solutes can pass. The negatively charged carboxylate groups lead to high separation selectivities between organic solutes of similar size but different charge. In single-solute diffusion experiments, neutral solutes permeate up to 263 times faster than negatively charged compounds of similar size. This selectivity is further enhanced in experiments with mixtures of these solutes. No permeation of the anionic compound was observed for over 24 h. In filtration experiments, these membranes separate anionic and neutral organic compounds while exhibiting water fluxes comparable to that of commercial membranes. Furthermore, carboxylate groups can be functionalized, creating membranes with nanopores with customizable functionality to enable a broad range of selective separations.

All inorganic cesium lead bromide (CsPbBr3) perovskite is a more stable alternative to methylammonium lead bromide (MAPbBr3) for designing high open-circuit voltage solar cells and display devices. Poor solubility of CsBr in organic solvents makes typical solution deposition methods difficult to adapt for constructing CsPbBr3 devices. Our layer-by-layer methodology, which makes use of CsPbBr3 quantum dot (QD) deposition followed by annealing, provides a convenient way to cast stable films of desired thickness. The transformation from QDs into bulk during thermal annealing arises from the resumption of nanoparticle growth and not from sintering as generally assumed. Additionally, a large loss of organic material during the annealing process is mainly from 1-octadecene left during the QD synthesis. Utilizing this deposition approach for perovskite photovoltaics is examined using typical planar architecture devices. Devices optimized to both QD spin-casting concentration and overall CsPbBr3 thickness produce...

peer-reviewed In the past decade or two, the field of nanophotonics has seen rapid development, empowered by introducing the concepts of plasmonics and metamaterials. The enabling feature behind this progress has been the use of noble metals that exhibit negative dielectric permittivities over a wide spectral range of visible and infrared wavelengths that allowed for manipulating the light on the subwavelength scale. Consequently, numerous interesting phenomena that otherwise do not exist in nature have been demonstrated in laboratories, but their transitions to practical applications have been painfully slow due to the large ohmic losses that are inherent in all metals. Doped semiconductors with lower losses have been proposed as new plasmonic materials to replace noble metals. Because the electron densities that are introduced with the artificial doping are always a few order of magnitude lower than what naturally available in metals, their plasma frequencies are shifted considerably toward longer wavelengths to the infrared (IR). This work compares these two categories of plasmonic media in structures that support either localized or propagating surface plasmon polaritons (SPPs) in mid-IR We have found that in both cases new plasmonic materials underperform noble metals in terms of enhancing optical field in localized SPPs and reducing SPP propagation loss in plasmonic waveguides. The cause of this subpar performance is the inherently low electron density that yields a significantly reduced plasma frequency compared to noble metals. This fundamental property associated with all new plasmonic materials dictates that, while new materials do hold a number of advantages, including tunability and ability to withstand high temperatures, noble metals, even with their ohmic losses, are not likely to be replaced in the foreseeable future. ACCEPTED peer-reviewed

Electro-optic modulation is a key function in optical data communication and possible future optical compute engines. The performance of modulators intricately depends on the interaction between the actively modulated material and the propagating waveguide mode. While a variety of high-performance modulators have been demonstrated, no comprehensive picture of what factors are most responsible for high performance has emerged so far. Here we report the first systematic and comprehensive analytical and computational investigation for high-performance compact on-chip electro-optic modulators by considering emerging active materials, model considerations and cavity feedback at the nanoscale. We discover that the delicate interplay between the material characteristics and the optical mode properties plays a key role in defining the modulator performance. Based on physical tradeoffs between index modulation, loss, optical confinement factors and slow-light effects, we find that there exist combinations of bias, material and optical mode that yield efficient phase or amplitude modulation with acceptable insertion loss. Furthermore, we show how material properties in the epsilon near zero regime enable reduction of length by as much as by 15 times. Lastly, we introduce and apply a cavity-based electro-optic modulator figure of merit, Δλ/Δα, relating obtainable resonance tuning via phase shifting relative to the incurred losses due to the fundamental Kramers-Kronig relations suggesting optimized device operating regions with optimized modulation-to-loss tradeoffs. This work paves the way for a holistic design rule of electro-optic modulators for high-density on-chip integration.

Plasmonic enhanced Schottky photodetectors operating on the basis of the internal photoemission process are becoming an alternative for the more conventional photodetectors based on interband transitions for light detection in the infrared. This is because such detectors typically consist of silicon and CMOS compatible metals, thus, allowing low cost and large scale fabrication. Most of the reports so far were focused on measuring the responsivity of the device. Here, we provide a detailed analysis for the optimization of internal photoemission based devices in terms of figure of merits such as signal-to-noise ratio (SNR) and noise equivalent power (NEP). Following the analysis, we experimentally demonstrate the operation of pyramidally shaped, silicon-based, internal photoemission detectors in the mid-infrared. The measured devices are capable of photodetection at wavelengths up to ∼2.5 μm. This paves the way for the use of plasmonic enhanced silicon photodetectors for a broad range of applications inclu...

The evolution of non-equilibrium carriers excited in the process of decay of surface plasmon polaritons (SPPs) in metal is described for each step – from the generation of carriers to their extraction from the metal. The relative importance of various carrier-generating mechanisms is discussed. It is shown that both the generation of carriers and their decay are inherently quantum processes as, for realistic illumination conditions, no more than a single SPP per nanoparticle exists at a given time. As a result, the distribution of non-equilibrium carriers cannot be described by a single temperature. It is also shown that the originally excited carriers that have not undergone a single electron-electron scattering event are practically the only ones that contribute to the injection. The role of momentum conservation in carrier extraction is discussed, and it is shown that, if all the momentum conservation rules are relaxed, it is the density of states in the semiconductor/dielectric that determines the ultimate injection efficiency. A set of recommendations aimed at improving the efficiency of plasmonic-assisted photodetection and (to a lesser degree) photocatalysis is made in the end.

In this chapter, we investigate vertical transistors based on hot electron transport—tunneling hot electron transfer amplifier (THETA). As compared to lateral transport devices such as HEMTs, electron transport can be defined by heterojunction growth at a scale shorter than 10 nm, and output conductance can be controlled through doping and epitaxial engineering. Furthermore, the power dissipation in a vertical device occurs over a volume rather than in a 2D sheet; the local temperature rise is not as significant as in the lateral case. THETA had been previously demonstrated in GaAs systems, and current gain in excess of 10 had been achieved with wide bandgap AlSbAs emitter at room temperature. GaN THETA has been reported in recent years, but the current gain in these devices has remained relatively low.

Proteins designed for supramolecular assembly provide a simple means to immobilize and organize enzymes for biotechnology applications. We have genetically fused the thermostable alcohol dehydrogenase D (AdhD) from Pyrococcus furiosus to a computationally designed cage-forming protein (O3-33). The trimeric form of the O3-33-AdhD fusion protein was most active in solution. The immobilization of the fusion protein on bioelectrodes leads to a doubling of the electrochemical operational stability as compared to the unfused control proteins. Thus, the fusion of enzymes to the designed self-assembling domains offers a simple strategy to increase the stability in biocatalytic systems.

Using ultralow loss waveguides and a novel cavity design, we demonstrate fully integrated lasers on silicon with a fundamental linewidth lower than 200 Hz. The lasers also possess an ultrawide wavelength tuning range of 110 nm across three optical communication bands (S+C+L). These are record results for all fully integrated semiconductor lasers that have ever been reported in literature.

Optical waveguides are vital components of data communication system technologies, but their scaling down to the nanoscale has remained challenging despite advances in nano-optics and nanomaterials. Recently, we theoretically predicted that the ultimate limit of visible photon guiding can be achieved in monolayer-thick transition metal dichalcogenides. Here, we present an experimental demonstration of light guiding in an atomically thick tungsten disulfide membrane patterned as a photonic crystal structure. In this scheme, two-dimensional tungsten disulfide excitonic photoluminescence couples into quasi-guided photonic crystal modes known as resonant-type Wood’s anomalies. These modes propagate via total internal reflection with only a small portion of the light diffracted to the far field. Such light guiding at the ultimate limit provides more possibilities to miniaturize optoelectronic devices and to test fundamental physical concepts. A monolayer WS2 membrane patterned as a photonic crystal sustains guided optical modes that propagate via total internal reflection.

Since optical refrigeration has been demonstrated in rare-earth doped media, its most logical application has been development of a radiation balanced laser (RBL). While efficient and versatile rare-earth solid state laser operates only on a few discrete wavelengths. At the same time semiconductor gain medium can be easily engineered to lase over the entire visible and near IR spectrum. But achieving cooling and RBL in semiconductor medium has proven elusive due to both fundamental (hard to simultaneously achieve gain and anti-Stokes luminescence) and practical (background absorption) reasons. Therefore, it would be worthwhile to consider an alternative, tandem structure in which rare earth doped medium would cool the optically pumped semiconductor laser. In this work we provide guidelines for development of such a laser and estimate its characteristics under realistic conditions.

This study aims to demonstrate the fabrication of radio-frequency (RF) metal-insulator-metal (MIM) polyimide capacitors on a flexible Kapton ™ (polyimide film) substrate using a purely additive manufacturing technology. The aerosol jet printing technology can effectively replace the use of bulky lumped components in the RF circuits such as filters, matching networks, oscillators, resonators, and mixers. Two capacitor geometries with areas of 0.25, and 0.5625 mm2have been printed. Optical profilometry of the printed metal capacitor plates and the polyimide (insulation) film show that they have average thicknesses of $\pmb{2.34 \pm 0.22\mu} \mathbf{m}$ and $\pmb{4.05 \pm 0.44\mu} \mathbf{m}$ , respectively. The measured capacitance for the set of capacitors are $\pmb{1.746\pm 0.231}\ \mathbf{pF}$ and $\pmb{2.513\pm 0.133}\mathbf{pF}$ , which is equivalent to a capacitance tolerance of 10% and 5%, respectively. The S-parameters were measured using the vector network analyzer up to frequency of 50 GHz and a lumped circuit model is extracted and presented through the Smith Chart using Advanced Design System TM. Moreover, the results of normalized measured capacitance and conductance as a function of temperature, adhesion, temperature (100°C/ice bath) cycling, and the maximum operating voltage of the capacitor are presented.