arXiv subjects

G. Gay

Publications and source records attributed to G. Gay.

5 recordsLinked to original sources

arXiv2006

Surface-wave interferometry on single subwavelength slit-groove structures fabricated on gold films

We apply the technique of far-field interferometry to measure the properties of surface waves generated by two-dimensional (2D) single subwavelength slit-groove structures on gold films. The effective surface index of refraction measured for the surface wave propagating over a distance of more than 12 microns is determined to be 1.016 with a measurement uncertainty of 0.004, to within experimental uncertainty of the expected bound surface plasmon-polariton (SPP) value for a Au/Air interface of 1.018. We compare these measurements to finite-difference-time-domain (FDTD) numerical simulations of the optical field transmission through these devices. We find excellent agreement between the measurements and the simulations for the surface index of refraction. The measurements also show that the surface wave propagation parameter exhibits transient behavior close to the slit, evolving smoothly from greater values asymptotically toward the value expected for the SPP over the first 2-3 microns of slit-groove distance. This behavior is confirmed by the FDTD simulations.

physics.optics↗

arXiv2006

Analysis of surface waves generated on subwavelength-structured silver films

Using transmission electron microscopy (TEM) to analyse the physical-chemical surface properties of subwavlength structured silver films and finite-difference time-domain (FDTD) numerical simulations of the optical response of these structures to plane-wave excitation, we report on the origin and nature of the persistent surface waves generated by a single slit-groove motif and recently measured by far-field optical interferometry. The surface analysis shows that the silver films are free of detectable oxide or sulfide contaminants, and the numerical simulations show very good agreement with the results previously reported.

physics.optics↗

arXiv2006

Surface wave generation and propagation on metallic subwavelength structures measured by far-field interferometry

Transmission spectra of metallic films or membranes perforated by arrays of subwavelength slits or holes have been widely interpreted as resonance absorption by surface plasmon polaritons (SPPs). Alternative interpretations involving evanescent waves diffracted on the surface have also been proposed. These two approaches lead to divergent predictions for some surface wave properties. Using far-field interferometry, we have carried out a series of measurements on elementary one-dimensional (1-D) subwavelength structures with the aim of testing key properties of the surface waves and comparing them to predictions of these two points of view.

physics.optics↗

arXiv2006

Optical Response of Nanostructured Surfaces: Experimental Investigation of the Composite Diffracted Evanescent Wave Model

Investigations of the optical response of subwavelength structure arrays milled into thin metal films has revealed surprising phenomena including reports of unexpectedly high transmission of light. Many studies have interpreted the optical coupling to the surface in terms of the resonant excitation of surface plasmon polaritons (SPPs), but other approaches involving composite diffraction of surface evanescent waves (CDEW) have also been proposed. We present here a series of measurements on very simple one-dimensional (1-D) subwavelength structures with the aim of testing key properties of the surface waves and comparing them to the CDEW and SPP models.

physics.optics↗

arXiv2002

2mm Wavelength VLBI of SiO Masers and AGN

In April 2002 an array of antennas operating at 129GHz successfully detected VLBI fringes on both continuum AGN and SiO maser sources. The 129GHz fringes on maser sources represent the highest frequency spectral line VLBI detections to date. The AGN 3C279 was detected on long baselines at both 129GHz (and at 147GHz, see Krichbaum et al in these proceedings) yielding fringe spacings of 50-56 micro arc seconds, an angular resolution record. The array consisted of the University of Arizona Kittpeak 12m antenna, the Heinrich Hertz 10m Telescope (HHT), and the IRAM 30m dish on Pico Veleta. At 129GHz, a number of evolved stars and several young stellar objects exhibit strong SiO maser emission in the v=1 J=3-2 transition. Preliminary cross power spectra of SiO masers around the red hypergiant VYCMa on the HHT-KittPeak baseline ~190km are consistent with multiple spatially separate maser spots associated with the star. Future observations will include continuum observations of the radio source at the Galactic Center, SgrA*, and higher frequency maser lines including HCN and methanol.

astro-ph↗