A5000177760- Photonic and Optical Devices
- Silicon Nanostructures and Photoluminescence
- Photonic Crystals and Applications
- Nanowire Synthesis and Applications
- Advanced biosensing and bioanalysis techniques
- Plasmonic and Surface Plasmon Research
- Semiconductor materials and devices
- Optical Coatings and Gratings
- Analytical Chemistry and Sensors
- Quantum Dots Synthesis And Properties
- Transition Metal Oxide Nanomaterials
- Anodic Oxide Films and Nanostructures
- Advanced Fiber Optic Sensors
- Advanced Fiber Laser Technologies
- Integrated Circuits and Semiconductor Failure Analysis
- Semiconductor Lasers and Optical Devices
- Mechanical and Optical Resonators
- Chalcogenide Semiconductor Thin Films
- Neural Networks and Reservoir Computing
- Nanofabrication and Lithography Techniques
- Optical Network Technologies
- Magneto-Optical Properties and Applications
- Biosensors and Analytical Detection
- Radiation Effects in Electronics
- Advanced Photonic Communication Systems
Vanderbilt University
2016-2025
Nashville Oncology Associates
2019
Center for Nanoscale Science and Technology
2013
Technion – Israel Institute of Technology
1986-2007
University of Rochester
2000-2006
Institute of Electrical and Electronics Engineers
2006
Instituto de Óptica "Daza de Valdés"
2005
Collegio Carlo Alberto
1999
University of Groningen
1999
University Medical Center Groningen
1999
We demonstrate a hybrid silicon–vanadium dioxide (Si-VO2) electro-optic modulator that enables direct probing of both the electrically triggered semiconductor-to-metal phase transition in VO2 and reverse from metal to semiconductor. By using two-terminal in-plane electrical switch atop single-mode silicon waveguide, change can be initiated probed optically, separating excitation measurement processes simplifying analysis metal-to-semiconductor dynamics. record switch-on time for high-speed...
The fields of photonic crystals and plasmonics have taken two different approaches to increasing light–matter interaction. Photonic crystal cavities increase temporal confinement light in a material, as represented by their high quality factor, while plasmonic structures spatial confinement, low mode volume. However, the inability simultaneously attain extreme remains barrier realizing ultimate control material maximum performance devices. Here, engineering unit cell incorporate deep...
Abstract Silicon materials remain unused for supercapacitors due to extreme reactivity of silicon with electrolytes. However, doped boast a low mass density, excellent conductivity, controllably etched nanoporous structure and combined earth abundance technological presence appealing diverse energy storage frameworks. Here, we demonstrate universal route transform porous (P-Si) into stable electrodes electrochemical devices through growth an ultra-thin, conformal graphene coating on the P-Si...
We report white light-emitting diodes fabricated with ultrasmall CdSe nanocrystals, which demonstrate electroluminescence from a size of nanocrystals (<2 nm) previously thought to be unattainable. These LEDs have excellent color characteristics, defined by their pure CIE coordinates (0.333, 0.333), correlated temperatures 5461−6007 K, and rendering indexes as high 96.6. The effect voltage on the trap states responsible for emission is also described.
The ability to highly localize light with strong electric field enhancement is critical for enabling higher-efficiency solar cells, sources, and modulators. While deep-subwavelength modes can be realized plasmonic resonators, large losses in these metal structures preclude most practical applications. We developed an alternative approach achieving subwavelength localization of the displacement fields that not accompanied by inhibitive losses. experimentally demonstrate a dielectric bowtie...
Optical phase change materials (O-PCMs) are being explored for a variety of photonic applications due to the extraordinarily large changes in optical properties that occur during electronic and/or structural transitions. Here, recent work integrating O-PCMs integrated silicon devices is presented. Conceptually proposed and experimentally realized thermo-optic, electro-optic, all-optical Si/O-PCM described perspectives on potential electro-optic modulators outlined.
Vanadium dioxide (VO(2)) is a promising reconfigurable optical material and has long been focus of condensed matter research owing to its distinctive semiconductor-to-metal phase transition (SMT), feature that stimulated recent development thermally photonic, plasmonic, metamaterial structures. Here, we integrate VO(2) onto silicon photonic devices demonstrate all-optical switching reconfiguration ultra-compact broadband Si-VO(2) absorption modulators (L < 1 μm) ring-resonators (R ~ λ(0))....
We investigate the wavelength- and polarization-dependence of photocurrent signals generated at few-layer MoS2-metal junctions through spatially resolved measurements. When incident photon energy is above direct bandgap MoS2, maximum response occurs for light polarization direction parallel to metal electrode edge, which can be attributed photovoltaic effects. In contrast, if below maximized when polarized in perpendicular indicating different generation mechanisms. Further studies show that...
A label-free optical biosensor based on a one-dimensional photonic crystal microring resonator with enhanced light-matter interaction is demonstrated. More than 2-fold improvement in volumetric and surface sensing sensitivity achieved compared to conventional sensors. The experimental bulk detection ~248nm/RIU of DNA proteins reported at the nanomolar scale. With minimum feature size greater 100nm, can be fabricated same standard lithographic techniques used mass fabricate resonators.
A ring resonator is patterned on a porous silicon slab waveguide to produce compact, high quality factor biosensor with large internal surface area available for enhanced recognition of biological and chemical molecules. The nature the allows molecules directly interact guided mode. Quality factors near 10,000 were measured resonators radius 25 μm. bulk detection sensitivity 380 nm/RIU was upon exposure salt water solutions. Specific nucleic acid demonstrated 4 pm/nM.
Phase-change materials (PCMs) have emerged as promising active elements in silicon (Si) photonic systems. In this work, we design, fabricate, and characterize a hybrid Si-PCM optical modulator. By integrating vanadium dioxide (a PCM) within Si waveguide, non-resonant geometry, demonstrate ~ 10 dB broadband modulation with PCM length of 500 nm.
Porous silicon waveguide biosensors that utilize grating couplers etched directly into porous are demonstrated for improved molecular detection capabilities. Molecules infiltrated through the where they can interact with a guided mode. Hybridization of nucleic acids inside is shown to significantly perturb wave vector mode and detected angle-resolved reflectance measurements. A sensitivity 7.3°/mM selectivity better than 6:1 compared mismatched sequences. Experimental results in good...
White-light emitting ultra-small CdSe nanocrystals present exciting possibilities in the area of solid-state lighting technology. In this work, thirteen dissimilar polymers were examined as potential encapsulants for these single-sized nanocrystals. Films encased characterized terms nanocrystal aggregation and changes to nanocrystals' natural emission. The Hildebrand Hansen solubility parameters each encapsulant found be correlated quality encapsulation achieved. Encapsulants with...
In this work, we demonstrate improved molecular detection sensitivity for silicon slab photonic crystal cavities by introducing multiple-hole defects (MHDs), which increase the surface area available label-free without degrading quality factor. Compared to crystals with L3 defects, adding MHDs into enabled a 44% in towards small refractive index perturbations due monolayer attachment of aminosilane molecule. Also, exhibited 18% higher bulk changes.
We report a label-free porous silicon membrane waveguide biosensor based on 1μm thick freestanding film with 100nm diameter pores. The sensor operates in the Kretschmann configuration. A formvar polymer provides robust adhesion of to rutile prism and enables confinement guided modes membrane. Attenuated total reflectance measurements are performed, along theoretical calculations, fully characterize waveguide. sensitivity is investigated through DNA hybridization detection limit 42nM was...
We demonstrate photothermally induced optical switching of ultra-compact hybrid Si-VO₂ ring resonators. The devices consist a sub-micron length ~70 nm thick patch phase-changing VO₂ integrated onto silicon resonators as small 1.5 μm in radius. semiconductor-to-metal transition (SMT) is triggered using 532 pump laser, while transmission probed tunable cw laser near 1550 nm. observe modulation greater than 10dB from modest quality-factor (~10³) resonances, well large -1.26 change resonant...
We demonstrate large area two-dimensional arrays of patterned nanoporous gold for use as easy-to-fabricate, cost-effective, and stable surface enhanced Raman scattering (SERS) templates. Using a simple one-step direct imprinting process, subwavelength (NPG) gratings are defined by densifying appropriate regions NPG film. Both the densified grating pattern shown to contribute SERS enhancement. The resulting substrates exhibit uniform enhancement factors at least 107 monolayer adsorbed...
A flow-through sensing platform based on open-ended porous silicon (PSi) microcavity membranes that are compatible with integration in on-chip sensor arrays is demonstrated. Because of the high aspect ratio PSi nanopores, performance closed-ended sensors limited by infiltration challenges and slow responses when detecting large molecules such as proteins nucleic acids. In order to improve molecule transport efficiency reduce response time, nanopore were used a scheme, allowing analyte...
We present a computational design for an integrated electro-optic modulator based on near-field plasmonic coupling between gold nanodisks and thin film of vanadium dioxide silicon substrate. Active modulation is achieved by applying time-varying electric field to initiate large changes in the refractive index dioxide. Significant decrease device footprint (200 nm x 560 nm) increase extinction ratio per unit length (9 dB/µm) compared state-of-the-art photonic modulators are predicted.
The design, fabrication, and characterization of a label-free Mach-Zehnder interferometer (MZI) optical biosensor that incorporates highly dispersive one-dimensional (1D) photonic crystal in one arm are presented. sensitivity this slow light MZI-based sensor scales with the length region. numerically simulated MZI 16 μm long region is 115,000 rad/RIU-cm, which sevenfold higher than traditional biosensors millimeter-length sensing regions. An experimental bulk refractive index detection...
Electrical and thermal modulation of porous silicon microcavities is demonstrated based on a change in the refractive index liquid crystals infiltrated matrix. Positive negative anisotropy are investigated, leading to controllable tuning both longer shorter wavelengths. Extinction ratios greater than 10 dB have been demonstrated. Larger attenuation can be achieved by increasing Q-factor microcavities.