Caterina Netti - Academia.edu (original) (raw)

Papers by Caterina Netti

Research paper thumbnail of Visualization of optical continuum evolution along a nonlinear waveguide

2006 Conference on Lasers and Electro-Optics and 2006 Quantum Electronics and Laser Science Conference, 2006

Research paper thumbnail of Engineering energy dispersion in photonic crystal waveguides: band gaps and optical trirefringence

Technical Digest. Summaries of papers presented at the Quantum Electronics and Laser Science Conference. Postconference Technical Digest (IEEE Cat. No.01CH37172)

ABSTRACT

Research paper thumbnail of Applications of Reproducible SERS Substrates for Trace Level Detection

Research paper thumbnail of 12-FOLD Symmetric Quasicrystals

VOL 404 13 APRIL 2000 www.nature.comEngineering Center and Office of Naval Research at Maryland, b... more VOL 404 13 APRIL 2000 www.nature.comEngineering Center and Office of Naval Research at Maryland, by the state of Texasthrough the Texas Center for Superconductivity at the University of Houston, and theDepartment of Energy at Argonne.Correspondence and requests for materials should be addressed to T. V.(e-mail: venky@squid.umd.edu).

Research paper thumbnail of Optical spectroscopy of neodymium-doped tantalum pentoxide slab waveguides

CLEO/Pacific Rim 2003. The 5th Pacific Rim Conference on Lasers and Electro-Optics (IEEE Cat. No.03TH8671)

Research paper thumbnail of Tuning surface-enhanced raman scattering with resonant localised plasmons

2006 Conference on Lasers and Electro-Optics and 2006 Quantum Electronics and Laser Science Conference, 2006

We demonstrate how the enhancement of SERS is correlated to the matching of localized plasmons at... more We demonstrate how the enhancement of SERS is correlated to the matching of localized plasmons at the pump laser wavelength, by designing and measuring a variety of nanostructured gold surfaces, showing both tuning and reproducibility.

Research paper thumbnail of Waveguide Group Velocity Determination by Spectral Interference Measurements in Near-Field Optical Scanning Microscopy

Measurement of spectral interference with a near-field scanning optical microscope is used to det... more Measurement of spectral interference with a near-field scanning optical microscope is used to determine directly the variation of group velocity between modes of a planar slab waveguide as the modes propagate along the guide.

Research paper thumbnail of Low-noise self-phase modulation continuum generation in high index tapered planar waveguide at 1040 nm

SPIE Proceedings, 2005

Continuum Generation (CG) in optical waveguides has been recently attracting widespread interest ... more Continuum Generation (CG) in optical waveguides has been recently attracting widespread interest in fields requiring large spectral bandwidth such as metrology and Optical Coherence Tomography (OCT). Real time and in-vivo tissue imaging with cell resolution (Deltaz<1mum) is rapidly becoming the ultimate frontier of several OCT medical applications. CG wavelength and bandwidth are the pertinent criteria to obtain ultra high imaging

Research paper thumbnail of Probing molecules by surface-enhanced Raman spectroscopy

SPIE Proceedings, 2006

ABSTRACT A new class of Surface-Enhanced Raman Scattering (SERS) substrates have been engineered ... more ABSTRACT A new class of Surface-Enhanced Raman Scattering (SERS) substrates have been engineered by exploiting both Photonic Crystal (PC) and semiconductor technologies. Gold coated inverted pyramids nanotextured substrates allow reproducibility <10% and enhancement factors > 106 over large areas. Modelling and optical characterization of the engineered structures is demonstrated. Examples of applications to amino acids and illicit drug detection are given. Concentrations as low as ppm-ppb (mg/mL to ng/mL) have been measured depending on the adsorbed analytes. Information on structure and conformation of the molecule is inferred due to the richer nature of SERS spectra.

Research paper thumbnail of Broadband angular measurement of rectangular photonic crystal superprisms

Photonic Crystal Materials and Devices III, 2005

We demonstrate the fabrication, characterization and simulation of visible wavelength superprism ... more We demonstrate the fabrication, characterization and simulation of visible wavelength superprism devices in photonic crystal waveguides. We studied the super refraction dependence on lattice symmetry orientation and for propagation angles close to the main symmetry orientation. A variety of rectangular lattices devices with various pitches and hole diameters as well as number of rows have been fabricated. We used our

Research paper thumbnail of <title>Octave-wide continuum generation in high-index planar waveguide by 1.5-μm femtosecond pump</title>

Commercial and Biomedical Applications of Ultrafast Lasers V, 2005

Ultra-high bandwidth continuum generation has been attracting enormous interest for applications ... more Ultra-high bandwidth continuum generation has been attracting enormous interest for applications in optical frequency metrology, low-coherence tomography, laser spectroscopy, dispersion measurements, sensor techniques and others. The acceptance of this new technology would greatly benefit from the availability of compact and user-friendly sources. High index planar devices provide a versatile and unique approach to continuum generation. The dispersion can be carefully

Research paper thumbnail of White light continuum generation in planar waveguides

Advanced Solid-State Photonics, 2004

Abstract A Low-noise white-light continuum with bandwidths up to an octave is demonstrated by pro... more Abstract A Low-noise white-light continuum with bandwidths up to an octave is demonstrated by propagating nanojoule femtosecond pulses in planar waveguides operating in the normal dispersion region at wavelengths far from the zero dispersion ...

Research paper thumbnail of Tuning Localized Plasmons in Nanostructured Metamaterials for Surface-Enhanced Raman Scattering Applications

Photonic Metamaterials: From Random to Periodic, 2006

ABSTRACT Reflectivity measurements of gold nanostructures graded in pitch and aperture size allow... more ABSTRACT Reflectivity measurements of gold nanostructures graded in pitch and aperture size allow investigation of localized plasmons. A simple model confirmed by simulations explains the plasmon resonances. Such arrays demonstrate highly unusual and enhanced Raman scattering.

Research paper thumbnail of Separation of photonic crystal modes using femtosecond time-of-flight in waveguides

Summaries of Papers Presented at the Quantum Electronics and Laser Science Conference

ABSTRACT

Research paper thumbnail of Mode propagation and radiative coupling in photonic crystal waveguides

Nonlinear Optics: Materials, Fundamentals and Applications, 2000

We demonstrate a new spectroscopic tool to measure mode propagation and radiative coupling in pho... more We demonstrate a new spectroscopic tool to measure mode propagation and radiative coupling in photonic crystal waveguides. Tuning and extinction of the symmetry-engineered photonic gaps, and dispersion of the leaky modes are obtained.

Research paper thumbnail of Confined Plasmons in Metallic Nanocavities

Physical Review Letters, 2001

Research paper thumbnail of Tuning localized plasmons in nanostructured substrates for surface-enhanced Raman scattering

Optics Express, 2006

Comprehensive reflectivity mapping of the angular dispersion of nanostructured arrays comprising ... more Comprehensive reflectivity mapping of the angular dispersion of nanostructured arrays comprising of inverted pyramidal pits is demonstrated. By comparing equivalently structured dielectric and metallic arrays, diffraction and plasmonic features are readily distinguished. While the diffraction features match expected theory, localised plasmons are also observed with severely flattened energy dispersions. Using pit arrays with identical pitch, but graded pit dimensions, energy scaling of the localised plasmon is observed. These localised plasmons are found to match a simple model which confines surface plasmons onto the pit sidewalls thus allowing an intuitive picture of the plasmons to be developed. This model agrees well with a 2D finite-difference time-domain simulation which shows the same dependence on pit dimensions. We believe these tuneable plasmons are responsible for the surface-enhancement of the Raman scattering (SERS) of an attached layer of benzenethiol molecules. Such SERS substrates have a wide range of applications both in security, chemical identification, environmental monitoring and healthcare.

Research paper thumbnail of Realisation of ultra-low loss photonic crystal slab waveguide devices

Microelectronics Journal, 2005

In this paper we demonstrate low loss transmission both above and below the primary band-gap for ... more In this paper we demonstrate low loss transmission both above and below the primary band-gap for a photonic crystal (PC) super-prism device consisting of 600 lattice periods. By modifying the refractive index of the holes, we reduce overall insertion loss to just 4.5 dB across the entire visible spectrum. We show that the remaining loss is predominantly due to impedance mismatch at the boundaries between patterned and unpatterned slab waveguide regions. Experimental loss measurements compare well with finite difference time domain simulations.

Research paper thumbnail of Experimental investigation of photonic crystal waveguide devices and line-defect waveguide bends

Materials Science and Engineering: B, 2000

Photonic crystal waveguide devices incorporating line-defect waveguide bends have been fabricated... more Photonic crystal waveguide devices incorporating line-defect waveguide bends have been fabricated. In this paper we present preliminary experimental analysis of these structures. Although evidence of photonic band-gap effects are observed in the spectra, transmission efficiency was found to be extremely low due to significant up-scattering losses from the holes. In order to quantify this loss mechanism, a detailed experimental and theoretical analysis of scattering effects in regular photonic crystal waveguide devices with band gaps at visible wavelength is presented. Field profiles in line defect structures are analysed using a FDTD (finite difference time domain) method.

Research paper thumbnail of Highly Ordered Macroporous Gold and Platinum Films Formed by Electrochemical Deposition through Templates Assembled from Submicron Diameter Monodisperse Polystyrene Spheres

Chemistry of Materials, 2002

Here we report a simple and versatile technique for the preparation of novel macroporous three-di... more Here we report a simple and versatile technique for the preparation of novel macroporous three-dimensional gold and platinum films with regular submicron spherical holes arranged in a close-packed structure. Gold and platinum films were prepared by electrochemical reduction of gold or platinum complex ions dissolved in aqueous solution within the interstitial spaces between polystyrene latex spheres (500 or 750 nm in diameter) assembled on gold surfaces. The latex sphere templates were subsequently removed by dissolving in toluene to leave the structured metal films. Scanning electron microscopy of the gold and platinum films shows a well-formed regular three-dimensional, porous structure consisting of spherical voids arranged in a highly ordered face-centered cubic (fcc) structure. The spherical voids have the same diameter as the latex spheres used to form the template. Within the metal film the spherical voids are interconnected through a series of smaller pores. The metallic framework is dense, self-supporting, and free from defects. X-ray studies show the metal to be polycrystalline with a grain size smaller than 100 nm. The optical reflectivity of the macroporous gold and platinum films shows strong diffractive optical properties, which are potentially useful in many existing and emerging applications.

Research paper thumbnail of Visualization of optical continuum evolution along a nonlinear waveguide

2006 Conference on Lasers and Electro-Optics and 2006 Quantum Electronics and Laser Science Conference, 2006

Research paper thumbnail of Engineering energy dispersion in photonic crystal waveguides: band gaps and optical trirefringence

Technical Digest. Summaries of papers presented at the Quantum Electronics and Laser Science Conference. Postconference Technical Digest (IEEE Cat. No.01CH37172)

ABSTRACT

Research paper thumbnail of Applications of Reproducible SERS Substrates for Trace Level Detection

Research paper thumbnail of 12-FOLD Symmetric Quasicrystals

VOL 404 13 APRIL 2000 www.nature.comEngineering Center and Office of Naval Research at Maryland, b... more VOL 404 13 APRIL 2000 www.nature.comEngineering Center and Office of Naval Research at Maryland, by the state of Texasthrough the Texas Center for Superconductivity at the University of Houston, and theDepartment of Energy at Argonne.Correspondence and requests for materials should be addressed to T. V.(e-mail: venky@squid.umd.edu).

Research paper thumbnail of Optical spectroscopy of neodymium-doped tantalum pentoxide slab waveguides

CLEO/Pacific Rim 2003. The 5th Pacific Rim Conference on Lasers and Electro-Optics (IEEE Cat. No.03TH8671)

Research paper thumbnail of Tuning surface-enhanced raman scattering with resonant localised plasmons

2006 Conference on Lasers and Electro-Optics and 2006 Quantum Electronics and Laser Science Conference, 2006

We demonstrate how the enhancement of SERS is correlated to the matching of localized plasmons at... more We demonstrate how the enhancement of SERS is correlated to the matching of localized plasmons at the pump laser wavelength, by designing and measuring a variety of nanostructured gold surfaces, showing both tuning and reproducibility.

Research paper thumbnail of Waveguide Group Velocity Determination by Spectral Interference Measurements in Near-Field Optical Scanning Microscopy

Measurement of spectral interference with a near-field scanning optical microscope is used to det... more Measurement of spectral interference with a near-field scanning optical microscope is used to determine directly the variation of group velocity between modes of a planar slab waveguide as the modes propagate along the guide.

Research paper thumbnail of Low-noise self-phase modulation continuum generation in high index tapered planar waveguide at 1040 nm

SPIE Proceedings, 2005

Continuum Generation (CG) in optical waveguides has been recently attracting widespread interest ... more Continuum Generation (CG) in optical waveguides has been recently attracting widespread interest in fields requiring large spectral bandwidth such as metrology and Optical Coherence Tomography (OCT). Real time and in-vivo tissue imaging with cell resolution (Deltaz&amp;amp;amp;amp;amp;amp;lt;1mum) is rapidly becoming the ultimate frontier of several OCT medical applications. CG wavelength and bandwidth are the pertinent criteria to obtain ultra high imaging

Research paper thumbnail of Probing molecules by surface-enhanced Raman spectroscopy

SPIE Proceedings, 2006

ABSTRACT A new class of Surface-Enhanced Raman Scattering (SERS) substrates have been engineered ... more ABSTRACT A new class of Surface-Enhanced Raman Scattering (SERS) substrates have been engineered by exploiting both Photonic Crystal (PC) and semiconductor technologies. Gold coated inverted pyramids nanotextured substrates allow reproducibility &lt;10% and enhancement factors &gt; 106 over large areas. Modelling and optical characterization of the engineered structures is demonstrated. Examples of applications to amino acids and illicit drug detection are given. Concentrations as low as ppm-ppb (mg/mL to ng/mL) have been measured depending on the adsorbed analytes. Information on structure and conformation of the molecule is inferred due to the richer nature of SERS spectra.

Research paper thumbnail of Broadband angular measurement of rectangular photonic crystal superprisms

Photonic Crystal Materials and Devices III, 2005

We demonstrate the fabrication, characterization and simulation of visible wavelength superprism ... more We demonstrate the fabrication, characterization and simulation of visible wavelength superprism devices in photonic crystal waveguides. We studied the super refraction dependence on lattice symmetry orientation and for propagation angles close to the main symmetry orientation. A variety of rectangular lattices devices with various pitches and hole diameters as well as number of rows have been fabricated. We used our

Research paper thumbnail of <title>Octave-wide continuum generation in high-index planar waveguide by 1.5-μm femtosecond pump</title>

Commercial and Biomedical Applications of Ultrafast Lasers V, 2005

Ultra-high bandwidth continuum generation has been attracting enormous interest for applications ... more Ultra-high bandwidth continuum generation has been attracting enormous interest for applications in optical frequency metrology, low-coherence tomography, laser spectroscopy, dispersion measurements, sensor techniques and others. The acceptance of this new technology would greatly benefit from the availability of compact and user-friendly sources. High index planar devices provide a versatile and unique approach to continuum generation. The dispersion can be carefully

Research paper thumbnail of White light continuum generation in planar waveguides

Advanced Solid-State Photonics, 2004

Abstract A Low-noise white-light continuum with bandwidths up to an octave is demonstrated by pro... more Abstract A Low-noise white-light continuum with bandwidths up to an octave is demonstrated by propagating nanojoule femtosecond pulses in planar waveguides operating in the normal dispersion region at wavelengths far from the zero dispersion ...

Research paper thumbnail of Tuning Localized Plasmons in Nanostructured Metamaterials for Surface-Enhanced Raman Scattering Applications

Photonic Metamaterials: From Random to Periodic, 2006

ABSTRACT Reflectivity measurements of gold nanostructures graded in pitch and aperture size allow... more ABSTRACT Reflectivity measurements of gold nanostructures graded in pitch and aperture size allow investigation of localized plasmons. A simple model confirmed by simulations explains the plasmon resonances. Such arrays demonstrate highly unusual and enhanced Raman scattering.

Research paper thumbnail of Separation of photonic crystal modes using femtosecond time-of-flight in waveguides

Summaries of Papers Presented at the Quantum Electronics and Laser Science Conference

ABSTRACT

Research paper thumbnail of Mode propagation and radiative coupling in photonic crystal waveguides

Nonlinear Optics: Materials, Fundamentals and Applications, 2000

We demonstrate a new spectroscopic tool to measure mode propagation and radiative coupling in pho... more We demonstrate a new spectroscopic tool to measure mode propagation and radiative coupling in photonic crystal waveguides. Tuning and extinction of the symmetry-engineered photonic gaps, and dispersion of the leaky modes are obtained.

Research paper thumbnail of Confined Plasmons in Metallic Nanocavities

Physical Review Letters, 2001

Research paper thumbnail of Tuning localized plasmons in nanostructured substrates for surface-enhanced Raman scattering

Optics Express, 2006

Comprehensive reflectivity mapping of the angular dispersion of nanostructured arrays comprising ... more Comprehensive reflectivity mapping of the angular dispersion of nanostructured arrays comprising of inverted pyramidal pits is demonstrated. By comparing equivalently structured dielectric and metallic arrays, diffraction and plasmonic features are readily distinguished. While the diffraction features match expected theory, localised plasmons are also observed with severely flattened energy dispersions. Using pit arrays with identical pitch, but graded pit dimensions, energy scaling of the localised plasmon is observed. These localised plasmons are found to match a simple model which confines surface plasmons onto the pit sidewalls thus allowing an intuitive picture of the plasmons to be developed. This model agrees well with a 2D finite-difference time-domain simulation which shows the same dependence on pit dimensions. We believe these tuneable plasmons are responsible for the surface-enhancement of the Raman scattering (SERS) of an attached layer of benzenethiol molecules. Such SERS substrates have a wide range of applications both in security, chemical identification, environmental monitoring and healthcare.

Research paper thumbnail of Realisation of ultra-low loss photonic crystal slab waveguide devices

Microelectronics Journal, 2005

In this paper we demonstrate low loss transmission both above and below the primary band-gap for ... more In this paper we demonstrate low loss transmission both above and below the primary band-gap for a photonic crystal (PC) super-prism device consisting of 600 lattice periods. By modifying the refractive index of the holes, we reduce overall insertion loss to just 4.5 dB across the entire visible spectrum. We show that the remaining loss is predominantly due to impedance mismatch at the boundaries between patterned and unpatterned slab waveguide regions. Experimental loss measurements compare well with finite difference time domain simulations.

Research paper thumbnail of Experimental investigation of photonic crystal waveguide devices and line-defect waveguide bends

Materials Science and Engineering: B, 2000

Photonic crystal waveguide devices incorporating line-defect waveguide bends have been fabricated... more Photonic crystal waveguide devices incorporating line-defect waveguide bends have been fabricated. In this paper we present preliminary experimental analysis of these structures. Although evidence of photonic band-gap effects are observed in the spectra, transmission efficiency was found to be extremely low due to significant up-scattering losses from the holes. In order to quantify this loss mechanism, a detailed experimental and theoretical analysis of scattering effects in regular photonic crystal waveguide devices with band gaps at visible wavelength is presented. Field profiles in line defect structures are analysed using a FDTD (finite difference time domain) method.

Research paper thumbnail of Highly Ordered Macroporous Gold and Platinum Films Formed by Electrochemical Deposition through Templates Assembled from Submicron Diameter Monodisperse Polystyrene Spheres

Chemistry of Materials, 2002

Here we report a simple and versatile technique for the preparation of novel macroporous three-di... more Here we report a simple and versatile technique for the preparation of novel macroporous three-dimensional gold and platinum films with regular submicron spherical holes arranged in a close-packed structure. Gold and platinum films were prepared by electrochemical reduction of gold or platinum complex ions dissolved in aqueous solution within the interstitial spaces between polystyrene latex spheres (500 or 750 nm in diameter) assembled on gold surfaces. The latex sphere templates were subsequently removed by dissolving in toluene to leave the structured metal films. Scanning electron microscopy of the gold and platinum films shows a well-formed regular three-dimensional, porous structure consisting of spherical voids arranged in a highly ordered face-centered cubic (fcc) structure. The spherical voids have the same diameter as the latex spheres used to form the template. Within the metal film the spherical voids are interconnected through a series of smaller pores. The metallic framework is dense, self-supporting, and free from defects. X-ray studies show the metal to be polycrystalline with a grain size smaller than 100 nm. The optical reflectivity of the macroporous gold and platinum films shows strong diffractive optical properties, which are potentially useful in many existing and emerging applications.