A5013839011- Advancements in Photolithography Techniques
- Laser Material Processing Techniques
- Phase-change materials and chalcogenides
- Surface Roughness and Optical Measurements
- Photonic and Optical Devices
- Optical Coatings and Gratings
- Chalcogenide Semiconductor Thin Films
- Metamaterials and Metasurfaces Applications
- Gold and Silver Nanoparticles Synthesis and Applications
- Plasmonic and Surface Plasmon Research
- Near-Field Optical Microscopy
- Nonlinear Optical Materials Studies
- Electron and X-Ray Spectroscopy Techniques
- Semiconductor Quantum Structures and Devices
- Nanofabrication and Lithography Techniques
- Photonic Crystals and Applications
- Advanced Chemical Physics Studies
- Liquid Crystal Research Advancements
- Integrated Circuits and Semiconductor Failure Analysis
- Solid State Laser Technologies
- Laser-induced spectroscopy and plasma
- Advanced Semiconductor Detectors and Materials
- Advanced Antenna and Metasurface Technologies
- Laser Design and Applications
- Advanced Surface Polishing Techniques
MIT Lincoln Laboratory
2014-2024
Massachusetts Institute of Technology
2014-2024
University of Central Florida
2017
LG Chem (South Korea)
2015
Nanosc (Sweden)
2015
K Lab (United States)
2000-2014
Lawrence Livermore National Laboratory
1996-2002
University of Arizona
1999
Institute of Physics
1997
Institute of Semiconductor Physics
1994-1997
Optical phase change materials (O-PCMs), a unique group of featuring drastic optical property contrast upon solid-state transition, have found widespread adoption in photonic switches and routers, reconfigurable meta-optics, reflective display, neuromorphic computers. Current materials, such as Ge-Sb-Te (GST), exhibit large both refractive index (delta n) loss k), simultaneously. The coupling properties fundamentally limits the function performance many potential applications. In this...
Active metasurfaces, whose optical properties can be modulated post-fabrication, have emerged as an intensively explored field in recent years. The efforts to date, however, still face major performance limitations tuning range, quality, and efficiency especially for non mechanical actuation mechanisms. In this paper, we introduce active metasurface platform combining phase covering the full 2$\pi$ range diffraction-limited using all-dielectric, low-loss architecture based on change...
Microsphere-assisted imaging emerged as a surprisingly simple way of achieving optical super-resolution imaging. In this work, we use movable PDMS thin films with embedded high-index barium titanate glass microspheres sample scanning capability was developed, thus removing the main limitation technology based on its small field-of-view.
Reconfigurable photonic systems featuring minimal power consumption are crucial for integrated optical devices in real‐world technology. Current active available foundries, however, use volatile methods to modulate light, requiring a constant supply of and significant form factors. Essential aspects overcome these issues the development nonvolatile reconfiguration techniques which compatible with on‐chip integration different platforms do not disrupt their performances. Herein, solution is...
Programmable and reconfigurable optics hold significant potential for transforming a broad spectrum of applications, spanning space explorations to biomedical imaging, gas sensing, optical cloaking. The ability adjust the properties components like filters, lenses, beam steering devices could result in dramatic reductions size, weight, power consumption future optoelectronic devices. Among candidates optics, chalcogenide-based phase change materials (PCMs) offer great promise due their...
A highly scalable approach for producing surface-enhanced Raman spectroscopy substrates is introduced. The novel method involves assembling individual nanoparticles in pre-defined templates, one particle per template, forming a high denisity of nanogaps over large areas, while decoupling nanostructure synthesis from placement. Detailed facts importance to specialist readers are published as "Supporting Information". Such documents peer-reviewed, but not copy-edited or typeset. They made...
Metal-dielectric nanolaminates represent a class of hyperbolic metamaterials with uniaxial permittivity tensor. In this study, we critically compare extraction nanolaminate samples using two techniques: polarized reflectometry vs. spectroscopic anisotropic ellipsometry. Both Au/MgF2 and Ag/MgF2 metal-dielectric stacks are examined. We demonstrate the applicability treatment multilayered material as medium derived optical parameters to those expected from effective approximation. also...
This work demonstrates a novel broadband optical switch, based on dynamic-scattering effect in liquid crystals (LCs). Dynamic-scattering-mode technology was developed for display applications over four decades ago, but displaced favor of the twisted-nematic LCs. However, with recent development more stable LCs, dynamic scattering provides advantages other technologies switching. We demonstrate polarization-insensitive attenuation light directly passing thought cell by 4 to 5 orders magnitude...
We report a technique to measure the mid-infrared photothermal response induced by tunable quantum cascade laser in neat liquid crystal 4-octyl-4′-cyanobiphenyl (8CB), without any intercalated dye. Heterodyne detection using Ti:sapphire of solid, smectic, nematic and isotropic phases allows direct weak normal mode absorption an inexpensive photodetector. At high pump power phase, we observe interesting peak splitting response. Tunable lasers that can access still stronger modes will...
We have established a method to quantify and optimize the plasmonic behavior of aluminum thin films by coupling spectroscopic ellipsometry into surface plasmon polaritons using liquid prism cell in modified Otto configuration. This procedure was applied Al deposited four different methods, as well single crystal substrates, determine broadband optical constants calculate figures merit. The best performance achieved with that been sputter-deposited at high temperatures 350°C, followed...
We report a new group of optical phase change materials Ge-Sb-Se-Te (GSST) with low loss from telecom bands to LWIR. further demonstrated GSST-integrated SiN photonics significantly improved switching performance over conventional GST alloys.
Wafer-level testing is crucial for process monitoring, post-fabrication trimming, and understanding system dynamics in photonic integrated circuits (PICs). Waveguide tap couplers are usually used to provide access the PIC components. These however incur permanent parasitic losses, imposing a trade-off between performance demands. Here we demonstrate transient coupler design based on optical phase change materials (O-PCMs). In their as-fabricated "on" state, enable broadband interrogation of...
Single-pulse irradiation of Au and Ag suspensions nanospheres nanodisks with 532-nm 4-ns pulses has identified complex optical nonlinearities while minimizing material damage. For all materials tested, we observe competition between saturable absorption (SA) reverse SA (RSA), RSA behavior dominating for intensities above ∼50 MW/cm2. Due to reduced laser damage in single-pulse experiments, the observed intrinsic nonlinear coefficients are highest reported date nanoparticles. We find size...
Ferroelectric domain inversion has been demonstrated in BaMgF(4) . Transparency measured to <140nm, and no change transmission was under 157-nm irradiation for >1.1x10(9) shots at 2mJ/cm(2) per pulse. First-order quasi-phase-matched generation of 157 nm is predicted by use grating periods as long 1.5mum. This material should permit shorter-wavelength chi((2)) frequency-mixing processes than with any other crystalline material.
This paper outlines the critical issues facing implementation of 157-nm lithography as a sub-100-nm technology. The status present technology for mask materials, pellicles, optical coatings, and resists is presented.
We present an approach for rational design and optimization of plasmonic arrays ultrasensitive surface enhanced infrared absorption (SEIRA) spectroscopy specific protein analytes. Motivated by our previous work that demonstrated sub-attomole detection surface-bound silk fibroin [Proc. Natl. Acad. Sci. U.S.A. 106, 19227 (2009)], we introduce here a general framework allows the numerical metamaterial sensor designs in order to maximize absorbance signal. A critical feature method is explicit...
Vanadium dioxide (VO2) is known to have a semiconductor-to-metal phase transition at ∼68 °C. Therefore, it can be used as tunable component of an active metamaterial. The lamellar metamaterial studied in this work composed subwavelength VO2 and Au layers designed undergo temperature controlled from the optical hyperbolic metallic phase. films VO2/Au stacks been fabricated electrical conductivity (transmission reflection) experiments. observed temperature-dependent changes reflection...
Abstract Active metasurfaces, whose optical properties can be modulated post-fabrication, have emerged as an intensively explored field in recent years. The efforts to date, however, still face major performance limitations tuning range, quality, and efficiency especially for non mechanical actuation mechanisms. In this paper, we introduce active metasurface platform combining phase covering the full 2π range diffraction-limited using all-dielectric, low-loss architecture based on change...
Photolithography using 157 nm pulsed fluorine lasers has emerged as the leading candidate technology for post-193-nm generation. Preliminary data have indicated that at there are optical materials transparent enough to enable fabrication of refractive elements, both in projection and illumination part train. However, a number critical issues still remain. Optical must show no appreciable degradation with laser irradiation. The availability photomask substrates be ascertained. coatings...
Our recent work has showed that diffractively coupled nanoplasmonic arrays for Fourier transform infrared (FTIR) microspectroscopy can enhance the Amide I protein vibrational stretch by up to 10(5) times as compared plain substrates. In this we consider computationally impact of a microscope objective illumination cone on array performance. We derive an approach computing angular- and spatially-averaged reflectance various numerical aperture (NA) objectives. then use show are perfectly...
Lithography at 157 nm is rapidly emerging as the industry-preferred technology for post-193 era. Its target application 100 to 70 generations, and it therefore widely viewed a “bridge” before next-generation lithographies are ready insertion into manufacturing. attractiveness stems from overlap in many areas with current practice shared infrastructure developed longer wavelengths. This article will review present status of lithography, emphasizing technological challenges various subsystems:...
We have studied the UV photon-induced interaction of molecular chlorine with a well-defined GaAs(110) surface under ultrahigh vacuum (UHV) conditions. Without illumination, was found to adsorb both molecularly and dissociatively at 85 K. Illumination chlorine-covered K 193, 248, 351 nm radiation led desorption Cl atoms formation AsCl3. suggest that reaction, is responsible for AsCl3 formation, initiated by dissociation. While direct absorption an individual Cl2 molecule may be cause...