This PDF file contains the front matter associated with SPIE Proceedings Volume 11694, including the Title Page, Copyright Information, and Table of Contents.

Recent progress is nanoscale photonics is driven by the physics of Mie resonances of high-index dielectric nanoparticles that provides a novel platform for localization of light in subwavelength photonic structures and opens new horizons for metamaterial-enabled photonics, or metaphotonics. In this talk, I will review the recent advances in Mie-resonant metaphotonics (also called "Mie-tronics") for isolated high-index dielectric nanoparticles and nanoparticle structures such as dielectric metasurfaces, and its applications to nonlinear and topological photonics.

We discuss meta-surfaces for which the transfer function is diagonal in the waveevector space. We show that such meta-surfaces can be used to perform spatial differentiation, squeeze free space, and generate a variety of optical beams with non-trivial properties associated with orbital or spin angular momentum of light.

We demonstrate a simple bias-free self-induced nonreciprocal device of an ultrathin bifacial dielectric metasurface. It is composed of two passive silicon-based metasurfaces exhibiting Fano and Lorentzian resonances, respectively. The narrowband resonant response, as well as the boosted field enhancement, lead to very low required input intensity values to obtain significant nonreciprocal transmission. Cascaded metasurface designs are also presented to further improve the geometric asymmetry and self-induced nonreciprocal performance. This work is expected to have several applications, such as nonreciprocal ultrathin coatings for the protection of sources or other sensitive equipment from external pulsed signals, circulators, and isolators.

Optical phase modulators are essential to large-scale integrated photonic systems at visible wavelengths, promising for many emerging applications. However, current technologies require large device footprints and either high power consumption or high drive voltage, limiting the number of active elements in a visible integrated photonic circuit. Here, we demonstrate visible silicon-nitride thermo-optical phase modulators based on adiabatic micro-ring resonators that offer at least a one-order-of-magnitude reduction in both device footprint and power consumption compared to waveguide phase modulators. Designed to operate in the strongly over-coupled regime, the micro-resonators provide 2 pi phase modulation with minimal amplitude variations, corresponding to less than 1 dB device insertion losses. By delocalizing the resonant mode, the adiabatic micro-rings also exhibit substantially improved robustness against fabrication variations.

Metasurface, 2D counterpart of metamaterials, has been of great interests due to its capability of manipulating light’ properties such as amplitude, phase, polarization, and angular momentum. Individual property of light is quite freely modulated using metasurface; modulation of the several properties in single metasurface has been intensively explored. This multifunctional metasurfacs has a high potential to increase optical information channels of the optical data storage device. In this study, we propose duplex metasurface which contains structurally colored print and vectorial holograms with eight polarization channels. The encoded structural color prints can be observed under white light and the fully polarized holograms can be reconstructed using coherent laser source with combination of output polarizer/retarder. As a proof-of-concept, we devise optical security platform using our multifunction metasurface and propose detection device using liquid crystal (LC) cell.

We present our latest work and investigation of exceptional point in plasmonic nanostructures. We show that the non-Hermitian singularity can be effectively deployed in small scale sensors and pave the path for engineering metamaterials with novel properties.

Hyperpolarizability is a measure of the nonlinear optical characteristics of natural or meta-atoms describing how the atoms become nonlinearly polarized by the induced local-field. However, determining hyperpolarizability in the case of structured plasmonic meta-atoms is not straightforward due to their relatively larger sizes, unique shapes, and the index of refraction of the surrounding dielectric medium. Also, the order-of-magnitude of hyperpolarizability may vary with the frequency of light especially when inter-band transitions in metals become dominant. Here, we experimentally and theoretically estimated the order-of-magnitude of the 1st-order hyperpolarizability of gold meta-atoms that can be used in designing nonlinear metasurfaces.

Recently, it has been suggested that chemical reactions can be facilitated by using mm-scale composites of plasmonic metal nanoparticles on porous oxides. This effect was shown recently to be predominantly associated with the heating induced by illumination. In this study, we study the sensitivity of the temperature rise to various parameters. We show that, the temperature rise in photocatalysts is typically weakly-dependent on the illumination wavelength, pulse duration, particle shape, size and density but is strongly sensitive to the beam size and the host thermal conductivity. Our results indicate that although plasmonic nanoparticles are thought of as nanoscale heat sources, the heat generation from which does not differ so much from macroscopic heat sources. On a more general level, this work is instrumental in uprooting some common misconceptions associated with the role of thermal effects in applications that rely on heat generation from a large number of particles.

Unidirectional wave propagation in nonreciprocal structures enables exciting opportunities to control and enhance light-matter interactions in extreme ways. In this talk, we present our recent efforts on this exciting topic with particular focus on nonreciprocal plasmonic structures. We theoretically demonstrate remarkable levels of field enhancement and confinement when a plasmonic waveguiding structure supporting one-way modes is suitably terminated. We show that this effect leads to a substantial boosting of nonlinear light-matter interactions, exemplified by an improvement of several orders of magnitude in the third-harmonic-generation efficiency. We also discuss our recent work on nonreciprocal nonmagnetic thermal radiation effects in plasmonic systems.

Wavelength conversion using plasmonic nanostructures has been attracting attention as a novel nonlinear optical effect occurred in nano-sized regions. In general, the second order nonlinear polarization does not occur in the isotropic metal, while the breaking symmetry on the metal surface is considered to permit the SHG (second harmonic generation). The radiation control of the SHG signal is essential in order to apply plasmonic nanostructures as wave conversion devices. However, its radiation control has been difficult because the second order nonlinear polarization on the metal surface is sensitive to the surface roughness. In this study, we demonstrated the control of the SHG radiation pattern and phase by the unique idea that the second order nonlinear polarization couples to the dipole plasmon mode.

Over the last few decades, extensive previous studies of the nonlinear response of metal nanoparticles report a wide variation of nonlinear coefficients, thus, revealing a highly confused picture of the underlying physics. Here, we provide a systematic study of the nonlinear response of metal spheres under continuous-wave illumination within a purely thermal model. The improved modeling allows us to demonstrate a much better match to experimental measurements of the scattering from single metal nanoparticles compared to previous attempts. We then use these results to study the thermo-optical nonlinearity of many-nanoparticle composites. We show that the thermo-optical nonlinearity of the composite is strongly sensitive to the host thermal conductivity only. Our results can be used to interpret correctly the differences in chemical reaction enhancements originating from the thermo-optical nonlinearity at different illumination intensities.

We demonstrate wideband flat bright-soliton Kerr-comb in thin-film foundry-compatible SiN platform. This is achieved using multi-segment coupled resonators. Multi-segment coupling with optimized coupling regions allow higher order dispersion engineering, paving the way toward wideband flat Kerr-comb around the pumping frequency. Here, using three coupling regions, we report a design based on thin-film SiN with 3dB spectral coverage of 3.8 THz around the pumping wavelength λ₀ = 1550 nm.

Discovering unconventional optical designs via machine-learning promises to advance on-chip circuitry, imaging, sensing, energy, and quantum information technology. In this talk, photonic design approaches and emerging material platforms will be discussed showcasting machine-learning-assisted topology optimization for thermophotovoltaic metasurface designs and machine-learning-enabled quantum optical measurements.

The systematic realization of the nature of the optical functionalities requires significant knowledge about the influence of nanostructure features on the propagation of electromagnetic waves. Due to the lack of such valuable information, cumbersome numerical calculations are currently the prevalent approach in designing nanostructures. In this talk, we introduce a novel technique based on manifold learning to reduce the complexity of the design problems. The developed algorithms provide valuable insights about the feasibility of a desired optical response and the roles of design parameters in forming the response through low-dimensional visualization. This extracted underlying information can be employed in different settings to accelerate the design of electromagnetic nanostructures for a wide range of applications.

We present a new approach for design of novel loss functions and introduce an optimal similarity-metric design for machine-learning-based design and knowledge discovery in nanophotonics. Machine-learning algorithms estimate the input-output relation in a photonic nanostructure by minimizing a loss function. We show that careful selection (from the available loss functions) or design of novel loss functions that are optimized for specific tasks can considerably improve the performance of machine-learning algorithms for design and knowledge discovery in photonic nanostructures. We also discuss the limitations and inefficacies of conventional loss functions that are currently being used for machine learning algorithms.

Inverse design has opened up the possibility of achieving high photonic device performances over broad spectral ranges. Recently, we have applied this technique to broadband polarization splitting. By sorting an input polarization state of light into four analyzer directions, the projection onto each of which is focused to a different detector element, we design a device that can reconstruct the polarization state. This concept has been shown with metasurfaces, but over a limited bandwidth. We show simulation results for a wide bandwidth device that efficiently sorts along four polarization directions, achieving high transmission and large contrast between the different states.

We present a new approach based on manifold learning for breaking the geometrical complexity of the photonic nanostructures during solving the inverse design problem. By encoding the high-dimensional spectral responses of a class of nanostructures into the latent space, we provide intuitive information about the underlying physics of these structures. We discuss the relations between the non-Euclidean distances in the latent space and changes in the optical responses and relate the movements in the latent space to the modifications of the optical responses for a class of nanostructures. Finally, we provide a new approach to use the insight about the role of design parameters to design nanostructures with minimal design complexity for a given functionality.

We propose a strategy for designing infrared absorbers with predefined spectral response using aluminum gratings as building blocks. We begin by defining 3 target spectra with resonances in the 7 – 15 micron wavelength range. Using FDTD simulations and interpolation, we create a reference library of aluminum gratings to investigate the relationship between their structural parameters and spectral properties. Next, we develop a search algorithm to find gratings from this library corresponding to resonances in the target spectra. Finally, we present an approach for designing hybrid structures from these gratings to generate each of the 3 target spectra.

In this work, while exploiting the latest multiple scattering software that can handle up to a million of particles, we explore the possibility to observe Anderson localization of light in a disordered medium. The proposed method is an excellent tool to manipulate the multipolar response from the spheres such that regimes can be identified where light localization happens. Moreover, by calculating the mean free path in the cluster via simulation data, the localization wavelengths can be now effectively pinpointed. Both features could provide clear guidelines for future optical transmission experiments and for designs utilizing Anderson localization of light.

Semiconductor quantum dots (QDs) feature high values of the two-photon absorption (TPA) cross-sections, enabling their applications in biosensing and nonlinear optoelectronics. However, the efficient QD photoluminescence (PL) intensity caused by TPA requires high-intensity laser excitation which hinders these applications. Placing the QDs in the micro- or nanocavities leads to a change in their PL properties. Particularly, near plasmon nanoparticles (open nanocavities) the local field may be enhanced by the localized plasmons, which will lead to an increase of the TPA efficiency. Alternatively, placing QDs in a photonic crystal may boost an increase of their PL quantum yield due to the Purcell effect and also increase their PL intensity at the photonic mode wavelength due to the redistribution of the density of photonic states. In this study, we have fabricated thin-film hybrid materials based on QDs placed near plasmonic nanoparticles or in the photonic crystal. We have demonstrated a 4.3-fold increase of the radiative recombination rate of QDs in the photonic crystal cavity under the two-photon excitation, resulting in the increase of the PL quantum yield. In turn, the coating of the QDs films with the gold nanorods led to the 12-fold increase in TPA at the maximum of the plasmon spectrum. Our results pave the way to a strong increase of the PL efficiency of the QDs under two-photon excitation for their applications in biosensing and nonlinear optoelectronics.

In this work, we demonstrate a lithography-free, polarization insensitive, angle-invariant trans-reflective color filter, which is composed of cost-effective, at and lossless dielectric ultra-thin films. The films with higher indices behave like a mirror of a Fabry Perot (FP) interferometer enclosing a layer of lower refractive index material between them. The transmission spectrum for the basic additive (red, green, blue (RGB)) and subtractive (cyan, magenta and yellow (CMY)) colors is studied first. The dimensions of the device are obtained with the help of the particle swarm optimization (PSO) algorithm for optimal results. The transmission/reflection efficiency obtained in the proposed device is above 99% with minimum full width at half maximum (FWHM) value of 74 nm at lower wavelengths. Similarly, the change in the cavity thickness sweeps the resonance wavelength across the visible regime. A minimum cross talk between blue and red colors is observed at higher wavelengths. The proposed design involves one deposition run, thus can be implemented for numerous applications.

Transparent electrodes implemented on semiconductors are essential components of optoelectronic devices, however, overcoming Fresnel limit and approaching perfect optical transmission together with high electrical conductivity are still a challenge. In this talk, by numerical simulations, we demonstrate a simple polarization-independent mechanism of infrared light funneling through subwavelength one-dimensional metal grating electrode integrated with monolithic high-contrast grating (MHCG). We show optical transmission of 97% through the electrode implemented at the interface between air and high refractive index semiconductor for radiation from broad infrared spectrum and revealing excellent electrical properties determined by sheet resistance below 1 Ohm/Sq.

Subwavelength one-dimensional gratings (SOGs) enable high quality factor (Q) Fano resonance, which yield significant advantages for integrated photonics applications. They are realized as high refractive index membranes suspended in air, or placed on low refractive index insulators. It was not yet analyzed whether it is possible to obtain high-Q in structures where refractive index contrast between membrane and cladding is smaller than 1. With the aid of numerical simulations we demonstrate high-Q resonance occurring for refractive index contrast between membrane and cladding as small as 0.5, allowing the realization of monolithically integrated semiconductor devices.

We describe recent progress in the development of spectrally tunable micro-engineered notch filters operating in the longwave infrared (LWIR) region from 8 to 12 µm based on using the guided-mode resonance (GMR) effect. The device structure consists of a subwavelength dielectric grating on top of a homogeneous waveguide using high-index dielectric transparent materials, i.e., germanium (Ge) with a refractive index of 4.0 and zinc selenide (ZnSe) with a refractive index of 2.4. We design the filters to reflect the incident broadband light at one (or more) narrow spectral band while fully transmitting the rest of the light. Filters based on one-dimensional (1-D) gratings are polarization-dependent and those based on two-dimensional (2-D) gratings are less polarization-dependent. We designed and characterized both 1-D and 2- D filters. Anti-reflection coatings (ARCs) were applied on the backside of some of the filter substrates to improve transmission over the entire spectral region. We carried out transmission measurements of these filters using two separate experimental setups—an automated tunable room-temperature quantum cascade laser (QCL) system as well as a modified Fourier Transform Infrared (FTIR) spectrometer with normal incidence of light on the sample. We will present filter designs, theoretical simulation, characterization experiments and results.

Deterministic illumination diffractive-diffusers have non-periodic short and medium scale topography. Because of the quasi-randomized locations and vertical sidewalls at phase transition boundaries, over-coating diffractive diffusers with thin film antireflection layers perturbs their function, resulting in illumination performance deviations and nonuniformities. To mitigate these effects, we added anti-reflection random nano-structures (rARSS) on the surface of three different classes of fused-silica multi-phase diffractive diffusers, using reactive-ion plasma etching. The diffusers were measured before and after the random nanostructure addition, using a polarized-laser scatterometer with a dynamic range of nine orders-of-magnitude. The bi-directional scatter distribution function (BSDF) was measured over the entire equatorial plane of incidence, to analyze the directionality of scattered light, and the impact of the rARSS on the optical performance of the diffusers. An overall Fresnel reflectivity suppression was measured in the directional illumination patterns, as well as, across the entire 180° angle-sweep. The designed deterministic illumination distribution patterns and contrast were unaffected by the presence of the rARSS.

Hyperbolic lattices tessellate the hyperbolic space, which affords the opportunity for an infinite number of regular tessellations. Thus, hyperbolic lattices significantly extend the design space typically associated with lattices in Euclidean space, and potentially provide access to unexplored wave phenomena. We here investigate the dynamic behavior of hyperbolic tessellations governed by interactions whose strength depends upon the distance of neighboring nodes. The exploration of their spectral characteristics illustrates a rich dynamic behavior, which is characterized by eigenstates that are primarily localized either at the center, or towards the boundary of the Poincare circle. The variation of the spectrum resulting from a hyperbolic translation of the lattice is evaluated in the context of phason dynamics. Specifically, the translation is considered as a phason of the hyperbolic lattice, which leads to a family of tessellations whose spectra lead to variations in eigenstates. Such variations identify modes that are strongly localized either at the center or at the boundary. The variation of these modes in terms of the translation identify an adiabatic transformation which is associated with the edge-to-edge pumping of selected eigenmodes.

Bound states in the continuum (BICs) represent topological singular points in the momentum space of photonic periodic media, such as photonic crystals. Although at-gamma BICs at k=0 have been known for long, off-gamma BICs with finite k vectors were discovered recently and gather special attention. Off-gamma BICs were formed at accidental condition, and there were no systematic ways to form them. In this talk, we propose and demonstrate a novel way to systematically form off-gamma BICs. We show that off-gamma BICs can be formed by spatial symmetry breaking of photonic crystals having at-gamma BICs at k=0. In addition, we show a large variety of generation and annihilation processes of BICs and circularly-polarized points enabled by manipulating the spatial symmetry, and two types of topological invariants govern the whole processes.

In this talk, we discuss our recent theoretical and experimental efforts in the context of non-Hermitian phenomena and parity-time symmetry, as well as in the exploration of exceptional points. In particular, we discuss our work in enabling parity-time symmetry, phase transitions and asymmetric transmission resonances based on temporal modulations, virtual excitations in the complex frequency domain and using evanescent fields. In addition, I will discuss our experimental work in observing these phenomena in a table-top fiber optics experiment using Brillouin scattering. Our results show that it is possible to observe the unusual scattering features associated with parity-time symmetry without the need for carefully controlled material gain distributions.

We apply the supersymmetric Darboux transformation to the optical Helmoltz wave equation to generate analytically complex-valued PT-symmetric potentials (physically a graded refractive index dielectric). PT-symmetry is then spontaneously broken controlling the amplitude of the imaginary part of the refractive index distribution. Consequently a resonance is detectable which is related to a singularity of the S matrix, responsible for extraordinary high transmission and reflection peaks in the scattering spectra. We demonstrate how controlling the resonance we can achieve different amplification rates up to four orders of magnitude at the exact singular point. Total transmission and very high reflection can be also obtained. All the visible portion of the spectrum can be spanned by enlarging the spatial width of the potential. All these potentials can be unified in a single device with the capability to dynamically control the imaginary part of the refractive index, thus defining a tunable dynamical optical filter behaving as a perfect amplifier, a transparent barrier or a high efficiency mirror with the main dimension of few hundreds of nanometers.

Recently, we introduced an optical cavity in the infrared fingerprint spectral region for enhanced sensing of chiral molecules within the cavity (Phys. Rev. Lett. 124, 033201 (2020)). Here, we discuss a simplified version of this cavity in which one of the formerly two silicon disk arrays is replaced by a homogenous, unstructured thin silicon film. We show that CD enhancement factors exceeding 100 are still possible, while the line shape of the resonances changes. Furthermore, we investigate the reduction of the CD enhancement versus molecule density due to non-helicity preserving interaction of light with the molecules in the cavity.

We present an original preliminary study dedicated to innovative pollutant plasmonic sensors exploiting the interaction properties between light and original nanostructured carbon based materials, in order to bring a real breakthrough in performance in terms of detection limit, quantification and sensitivity. The detection of our pesticide is based on the variation of the optical properties of the materials used in the presence of the molecule to be detected. We propose two ways of investigation that are i) the Surface Plasmon Resonance detection (SPR) in Kretschmann configuration and ii) the use of an original functionalized nano structured organization based on the use of functionalized gold nanoparticles with carbon materials.

Aluminum-Graphene based plasmonic sensor has been proposed for bio-sensing applications and analyzed for the resonant angle interrogation in the communication band. The addition of the graphene layer above a thin Aluminum metal layer, separated by a high index dielectric Silicon layer is considered. The performance parameters such as sensitivity, reflectivity-amplitude, and figure of merit are analyzed and compared with the conventional plasmonic sensors for the wavelength of 1550 nm. The combination of graphene and silicon layer leads to stronger interactions with biomolecules along with improved sensitivity. The simulated results show that the increase in the number of graphene layers helps to further increase the sensitivity of the biosensor. The maximum sensitivity observed for the plasmonic device was found to be 131°/RIU at the wavelength of 1550 nm.

The coupling between spin, charge, and lattice degrees of freedom plays an important role in a wide range of fundamental phenomena. Monolayer semiconductor is an emerging platform for studying these coupling effects due to unique spin-valley locking physics for hosting rich excitonic species and reduced screening for strong Coulomb interaction. In this talk, I will present the observation of both symmetry-allowed and -forbidden valley phonons, i.e. phonons with momentum vectors pointing to the corners of Brillouin zone, in a monolayer semiconductor WSe2. We unravel a series of photoluminescence peaks as valley phonon replicas of neutral and charged dark excitons, as well as intrinsic donor bound excitonic states with anomalously long population lifetime (> 5 µs).Our work shows monolayer WSe2 is a prime candidate for studying interactions between spin, pseudospin, and zone-edge phonons.

This Conference Presentation, “Programmable hyperbolic polaritons in van der Waals semiconductors,” was recorded for the Photonics West 2021 Digital Forum.

At the core of most quantum technologies, including quantum networks, quantum computers and quantum simulators, is the development of homogeneous, long lived qubits with excellent optical interfaces, and the development of high efficiency and robust optical interconnects for such qubits. To achieve this goal, we have been studying color centers in diamond (SiV, SnV) and silicon carbide (VSi in 4H SiC), in combination with novel fabrication techniques, and relying on the powerful and fast photonics inverse design approach that we have developed. We illustrate this with a number of demonstrated devices, including efficient photon interfaces for color centers in diamond and in SiC, and spectrally reconfigurable quantum emitters.

Quantum memories are a key tool for optical quantum information processing. Several physical implementations have been suggested. Photonic nano- and microstructures can significantly improve light matter interaction and in this way facilitate efficient photon storage. In this presentation we will introduce a photonics light cage as an engineered photonic structure to improve the performance of quantum memories based on warm atomic (Cs) vapor. Based on first results we derive the improved storage parameters of such a device and discuss prospect for integration into quantum networks.

Nearly all existing applications of quantum photonics require strings of single indistinguishable photons produced at high rates. Plasmonic nanostructures allow a targeted and strong enhancement of light-matter interaction in a broad wavelength range, boosting single-photon emission rates from solid-state quantum defects beyond both the rate of dipole dephasing and that of plasmon absorption in metals. We establish simple and intuitive fundamental enhancement limits for plasmonic systems coupled to quantum emitters and present practical methods for achieving these advantageous regimes. We also discuss methods for the on-chip integration of such single-photon sources and related opportunities for the readout of solid-state spins.

Photoluminescence (PL) properties of semiconductor quantum dots (QDs) may be significantly improved by forming hybrid structures with plasmonic nanoparticles (PNPs). In general, three main effects can be observed when QDs are placed near PNPs – a local enhancement of excitation, acceleration of radiative recombination rate (Purcell effect), and acceleration of nonradiative relaxation rate due to the metal-induced energy transfer. All these effects lead to an increase in PL quantum yield (QY), excitonic (EX) and biexcitonic (BX) states and to the strong reduction of PL lifetime. In this study, we investigated the EX and BX PL parameters of single QDs in the vicinity of PNPs at different overlapping between the excitation wavelength, QDs PL, and PNPs extinction spectra. Here, we have fabricated thin films of QDs separated from the environment by the polymer spacer, and placed PNPs atop of these structures under the continuous observation of optical parameter of the same single QD. We have found that the excitation may be strongly increased in the case of a strong spectral overlap between excitation band and PNPs extinction. Nevertheless, the EX QY is strongly reduced by the energy transfer. In the case of strong spectral overlap between QDs PL and PNPs extinction, the radiative rate is increased, which leads to an increase of both EX and BX QYs and to a near-unity BX-to-EX QY ratio. Finally, we managed to combine these two effects in one material with a synergistically increased PL intensity, ultrashort PL lifetime, and levelling of EX and BX QY.

Precise positioning of single quantum dots (QDs) in photonics crystal (PhC) cavities with nanometer-scale accuracy offers great promise for on-chip integrated quantum photonic circuit. In such coupled QD-cavity system, the decoherence fundamentally affects the coherent control for quantum communication and information processing. However, accessing to the strong-coupling regime and the impact of pure dephasing in such system have been rarely reported yet. Here, relying on our unique site-controlled pyramidal InGaAs/GaAs QDs – high-Q-PhC cavities platform, we investigate the cavity quantum electrodynamics towards strong-coupling regime mediated by pure dephasing. We demonstrate the anti-crossing and mutual linewidth narrowing of the single excitonic emission strongly coupled to cavity mode near resonance. We further present the signatures of Rabi-like oscillation and quantum beating between upper and lower branch of polariton.

It has been a long-time dream of mankind to design materials with tailored properties. In recent years, the focus of our work has been the design of phase change materials. In today’s talk, it will be shown that only a well-defined group of materials utilizes a unique bonding mechanism (metavalent bonding), which can explain many of the characteristic features of crystalline phase change materials. In particular, we will present a novel map, which separates the known strong bonding mechanisms of metallic, ionic and covalent bonding, which provides further evidence that metavalent bonding is a novel and fundamental bonding mechanism. This insight is subsequently employed to design phase change materials for photonic applications. We will demonstrate how the optical contrast can be tuned in different regions of the spectral range, including the realization of plasmonic phase change materials.

The demonstration of a photo-induced insulator-to-metal transition in vanadium dioxide (VO₂) on a picosecond time scale in the mid-1990s foreeshadowed application of this photo-induced phase transition in silicon photonics devices. The talk introduces our current understanding of the phase-transition physics, but focuses on our recent demonstrations of sub-picosecond switching of cw and ultrafast signal pulses in silicon and silicon nitride waveguides. Direct in-line modulation of signal pulses achieves only modest contrast ratios. However, similar switching strategies deploying VO₂ on resonant structures promise substantially higher contrast with smaller switching energies in silicon photonic structures with micron-scale form factors.

We present a dynamic metasurface platform by incorporating the phase-change alloy Ge2Sb2Te5 (GST) into metal-dielectric meta-atoms for active and non-volatile tuning of the optical response. We systematically design a unit cell, which selectively controls the fundamental plasmonic-photonic resonances of the metasurface via the dynamic change of the GST crystalline state. As a proof-of-concept, we experimentally demonstrate miniaturized tunable metasurfaces that globally manipulate amplitude and phase of incident light necessary for near-perfect absorption and anomalous/specular beam deflection, respectively. Our findings further substantiate reconfigurable hybrid metasurfaces as promising candidates for the development of miniaturized energy harvesting and optical signal processing devices.

We demonstrate a new platform for reconfigurable third-order nonlinear photonic devices formed by silicon dioxide (SiO2)-Sb2S3(Sb2Se3)-SiO2 subwavelength Fabry-Perot cavities on a gold (Au) reflector, which exhibit giant third-harmonic generation (THG) modulations with enhanced efficiency. The use of the phase-change dichalcogenides (Sb2S3 or Sb2Se3) enables a wide tuning range of the THG response. The devices work at dispersion-engineered THG resonances at the crystalline phase (c-phase) of the PCC, which numerically exhibit c-phase THG flows a few 100 times more than those at the amorphous phase (a-phase) of the PCC at near-infrared excitation wavelengths.

Traditional metal nanostructures and thin-films are the fundamental building blocks for photonic devices, yet they are intrinsically limited by the pre-defined dielectric function, i.e. permittivity. Alternatively, the permittivity of alloyed structures can be engineered by tuning their chemical compositions, which allows for customization of the optical responses. Here we present several alloy-based systems (including Ag-Au, Al-Cu, Pd-Au, among others) and demonstrate how their optical properties are tailored with varying chemical compositions. Examples of their applications in super-absorbing, hydrogen sensing and hot carrier devices are also introduced.

We propose a Fabry-Pérot type optical cavity based on an array of double dielectric nano-cylinder arrays. Fabry-Pérot cavity at double cylinder array are formed by two dielectric cylinder arrays. Double dielectric nano-cylinder arrays with a period of 660 nm shows high quality factor than 10^6. Also, the Fabry-Pérot resonant wavelengths and quality factors can be tuned by controlling the gap between double dielectric cylinders. Specifically, the quality factor and Fabry-Pérot resonant wavelengths, which are not much affected by the horizontal alignment of double cylinders. Our structure has simplicity and high efficiency. Which can be used in combination with laser and filter.

We investigate hybrid dielectric-metallic transmission color filters for cost-effective, narrow linewidth filters that are fully CMOS compatible. Through the interference of the resonance phenomena in a metallic hole array with a magnetic dipole resonance in a dielectric nanopillar, a narrow linewidth transmission window is opened. An additional metal cover on top of the pillar further suppresses transmission at longer wavelengths due to a localized surface plasmon polariton. FDTD simulations predict a transmission of over 50% and a linewidth of down to 25 nm for the green filter. The out-of-band suppression is lower compared to previously reported metal-insulator-metal filters.

We propose an interconnect model for multi-chip modules based on integration of a silicon photonic chip with single-mode polymer waveguides fabricated on the low-cost glass interposer technology. We present a detailed power-budget analysis of the on-chip photonic interconnect capable of 1 Tb/s chip-to-chip interconnection bandwidth. For this analysis, we consider state-of-the art photonics foundry modulators and detectors. We also discuss efficient-coupling strategies between the interconnect waveguides and the silicon photonic chip. Our analysis identifies key design parameters impacting the overall performance of the proposed interconnection approach in terms of energy-consumption, distance, and bandwidth and compare its performance with alternative approaches.

We demonstrate high quality factor (high-Q) air-clad optical microresonator in a thinfilm LPCVD-SiN, with loaded quality factor of 1.55 M at the near visible wavelength, suitable for interaction with Rb atoms for single atom detection. This record is achieved with no chemical mechanical polishing or high-temperature post-processing, enabling future fully integrated devices with optoelectronic circuitry.