Mid-infrared photonic sensors based on metamaterial structures

In this work three different metallic metamaterials (MMs) structures such as asymmetric split ring resonators (A-SRRs), dipole and split H-shaped (ASHs) structures that support plasmonic resonances have been developed. The aim of the work involves the optimization of photonic sensor based on plasmonic resonances and surface enhanced infrared absorption (SEIRA) from the MM structures. The MMs structures were designed to tune their plasmonic resonance peaks in the mid-infrared region. The plasmonic resonance peaks produced are highly dependent on the structural dimension and polarisation of the electromagnetic (EM) source. The ASH structure particularly has the ability to produce the plasmonic resonance peak with dual polarisation of the EM source. The double resonance peaks produced due to the asymmetric nature of the structures were optimized by varying the fundamental parameters of the design. These peaks occur due to hybridization of the individual elements of the MMs structure. The presence of a dip known as a trapped mode in between the double plasmonic peaks helps to narrow the resonances. A periodicity greater than twice the length and diameter of the metallic structure was applied to produce narrow resonances for the designed MMs. A nanoscale gap in each structure that broadens the trapped mode to narrow the plasmonic resonances was also used. A thickness of 100 nm gold was used to experimentally produce a high quality factor of 18 in the mid-infrared region. The optimised plasmonic resonance peaks was used for detection of an analyte, 17β-estradiol. 17β-estradiol is mostly responsible for the development of human sex organs and can be found naturally in the environment through human excreta. SEIRA was the method applied to the analysis of the analyte. The work is important in the monitoring of human biology and in water treatment. Applying this method to the developed nano-engineered structures, enhancement factors of 10^5 and a sensitivity of 2791 nm/RIU was obtained. With this high sensitivity a figure of merit (FOM) of 9 was also achieved from the sensors. The experiments were verified using numerical simulations where the vibrational resonances of the C-H stretch from 17β-estradiol were modelled. Lastly, A-SRRs and ASH on waveguides were also designed and evaluated. These patterns are to be use as basis for future work

Dual polarization operation of nanostructure arrays in the MIR region

In this paper, we report on arrays of asymmetric split H-shape nanostructures tuned to produce two distinct resonances at wavelengths that range from 3 μm to 7 μm. The electric-field of the incident wave has been both polarized parallel to the vertical asymmetric dipole arms and polarized across the 50 nm gap in the asymmetric horizontal bar. We have produced resonance quality factors as large as 26 in the mid-infrared region

Array metasurfaces for biomedical sensing at infra-red wavelengths

Detection and identification of biomedically significant molecules is an important application in infra-red (IR) spectroscopy. This presentation will consider some of the significant features of the different alternative building-block elements that can be used in array metasurfaces for enhanced detection sensitivity. The presentation will also address techniques and issues associated with the deposition and localisation of biological and organic chemical molecular material for detection and measurement using IR spectroscopy

Index of development plans in Berkshire

SIGLEAvailable from British Library Document Supply Centre-DSC:q97/16356 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Approximating data and statistical procedures. I. Approximating data

SIGLEAvailable from TIB Hannover: RR 8460(2003,7) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Gold asymmetric split ring resonators (A-SRRs) for nano sensing of estradiol

Recent advances have seen asymmetric split ring resonators (A-SRRs) developed as sensing elements to record a shift in their peaks when there is a corresponding change in the surrounding environment. These studies have led to the investigation of Fano resonances associated with the coupling of the resonances of the A-SRRs with the molecular resonances of the analyte. The hormone estradiol (E2) was dissolved in ethanol and evaporated, leaving thickness of a few hundreds of nanometres on top of gold A-SRRs on a silica substrate. The reflectance was measured and a red shift is recorded from the resonators plasmonic peaks. The geometric sizes of the ASRRs are calculated to tune the plasmonic resonances near the molecular resonance of the C-H stretch at nominally 3.33 microns. Corresponding Lumerical modelling of the experimental data is performed using only the intensity and wavelength to match the Fano resonance at modified wavelengths of 3.42 and 3.49 microns

BRS-Transformationen und Slavnov-Taylor-Identitaeten in einem endlichdimensionalen Modell

Available from TIB Hannover: RN 6068(25)+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Progress in metamaterial fishnet formed by nanoimprint lithography and asymmetric split ring resonators (A-SRRs) for sensing

Metamaterial structures fabricated using nanoimprint lithography, allow large areas to be patterned quickly through multiple use of a nanoimprint stamp. The fabrication process produces fishnet structures of various dimensions on a polymer layer with metal-dielectric-metal compressed rectangular pillars. Simulations show negative refractive index and good figures of merit. However both of these figures could be increased by removal from the underlying polymer structure. We also report on the use of asymmetric spilt ring resonators used to detect small quantities of hormone estradiol by tuning the plasmonic resonances near the molecular resonance of the C-H stretch at nominally 3.31 microns