Frequency-Spectra-Based High Coding Capacity Chipless RFID Using an UWB-IR Approach

A novel methodology is proposed to reliably predict the resonant characteristics of a multipatch backscatter-based radio frequency identification (RFID) chipless tag. An ultra-wideband impulsion radio (UWB-IR)-based reader interrogates the chipless tag with a UWB pulse, and analyzes the obtained backscatter in the time domain. The RFID system consists of a radar cross-section (RCS)-based chipless tag containing a square microstrip patch antenna array in which the chipless tag is interrogated with a UWB pulse by an UWB-IR-based reader. The main components of the backscattered signal, the structural mode, and the antenna mode were identified and their spectral quality was evaluated. The study revealed that the antenna-mode backscatter includes signal carrying information, while the structural mode backscatter does not include any tag information. The simulation findings were confirmed by experimental measurements obtained in an anechoic chamber environment using a 6-bit multipatch chipless RFID tag. Finally, the novel technique does not use calibration tags and can freely orient tags with respect to the reader.

Ultrastrong coupling in single plexcitonic nanocubes

Light-matter strong coupling is defined when the coupling strength exceeds the losses in the system, whereas ultrastrong coupling is not simply strong coupling with even larger coupling strength. Instead, ultrastrong coupling regime arises when the coupling strength is comparable to the transition frequency in the system. At present, ultrastrong light-matter interactions have been achieved in superconducting circuits, semiconductor polaritons, and organic molecules, where these systems are typically at the micrometer scale. In this work, we investigated ultrastrong coupling in a nanoparticle plexcitonic system, i.e. a single gold nanocube coated with quantum emitters and positioned on a gold film. We observed a normalized coupling rate η ~ 0.12 to the antenna mode in such coated nanocube-on-mirror (c-NCoM) configuration at the multilayer emitter level. In contrast to the gap mode that squeezes all the optical fields into the gap region, the antenna mode in c-NCoM provides multiple exterior hot spots at the upper corners of the nanocube, which can be exploited for qubit entanglement within a single nanocube. The concurrence between adjacent emitters is estimated up to 0.6. This theoretical study establishes a promising route toward building a scalable quantum network using single plexcitonic nanocubes as quantum nodes.

Effect of Film Thickness on the Far- and Near-Field Optical Response of Nanoparticle-on-Film Systems

<p>We study the near-field and far-field optical response of nanoparticle-on-film systems using single-nanoparticle spectroscopy and numerical simulations. We find that the optical spectra contain three dominant modes - a transverse dipole and quadrupole mode, and a dominant vertical antenna mode. We vary the thickness of the metal film from 10 – 45 nm, and find that the vertical antenna mode wavelength is nearly independent of the film thickness. In contrast, we find that the associated near-field enhancement in the gap between the particle and the film strongly depends on the film thickness. This trend is also observed in the far-field where the vertical antenna mode strongly increases in amplitude for increasing film-thicknesses up to the skin depth of gold. These findings are in good agreement with a numerical model and pave the way to study field-mediated processes such as fluorescence, SERS, and localized chemistry at the same resonance wavelength but at varying degrees of field enhancement.</p>

Effect of Film Thickness on the Far- and Near-Field Optical Response of Nanoparticle-on-Film Systems

<p>We study the near-field and far-field optical response of nanoparticle-on-film systems using single-nanoparticle spectroscopy and numerical simulations. We find that the optical spectra contain three dominant modes - a transverse dipole and quadrupole mode, and a dominant vertical antenna mode. We vary the thickness of the metal film from 10 – 45 nm, and find that the vertical antenna mode wavelength is nearly independent of the film thickness. In contrast, we find that the associated near-field enhancement in the gap between the particle and the film strongly depends on the film thickness. This trend is also observed in the far-field where the vertical antenna mode strongly increases in amplitude for increasing film-thicknesses up to the skin depth of gold. These findings are in good agreement with a numerical model and pave the way to study field-mediated processes such as fluorescence, SERS, and localized chemistry at the same resonance wavelength but at varying degrees of field enhancement.</p>