Search results for "Hertz"

Devices based on semiconductor nanowires

2009

Recently, nanoelectromechanical systems (NEMS) have attracted much attention due to their unique properties and possible applications that differ greatly from those of microelectromechanical systems. NEMS operating frequencies may achieve giga- and terahertz levels and their power consumption and heat capacity is extremely low. Moreover, integration levels may reach 1012 devices per cm−2. In this review, we present techniques for integrating semiconductor materials in NEMS. In particular, we examine fabrication, structure, properties and potential applications of two main classes of NEMS, namely, resonators and switches.

Versatile metal-wire waveguides for broadband terahertz signal processing and multiplexing.

2022

AbstractWaveguides play a pivotal role in the full deployment of terahertz communication systems. Besides signal transporting, innovative terahertz waveguides are required to provide versatile signal-processing functionalities. Despite fundamental components, such as Bragg gratings, have been recently realized, they typically rely on complex hybridization, in turn making it extremely challenging to go beyond the most elementary functions. Here, we propose a universal approach, in which multiscale-structured Bragg gratings can be directly etched on metal-wires. Such an approach, in combination with diverse waveguide designs, allows for the realization of a unique platform with remarkable str…

Photoswitchable Micro-Supercapacitor Based on a Diarylethene-Graphene Composite Film

2017

Stimuli-responsive micro-supercapacitors (MSCs) controlled by external stimuli can enable a wide range of applications for future on-chip energy storage. Here, we report on a photoswitchable MSC based on a diarylethene-graphene composite film. The microdevice delivers an outstanding and reversible capacitance modulation of up to 20%, demonstrating a prototype photoswitchable MSC. Terahertz spectroscopy indicates that the photoswitching of the capacitance is enabled by the reversible tuning of interfacial charge injection into diarylethene molecular orbitals, as a consequence of charge transfer at the diarylethene-graphene interface upon light modulation.

Near-Field Enhancement Optimization by Tapering Terahertz Gold Nanoantennas

We will present the simulation, fabrication and characterization of gold tapered nanoantennas, whose structure is optimized for terahertz near-field enhancement.

Gamma Vel cluster membership and IMF

2016

Understanding the properties of young open clusters, such as the Initial Mass Function (IMF), star formation history and dynamic evolution, is crucial to obtain reliable theoretical predictions of the mechanisms involved in the star formation process. We want to obtain a list, as complete as possible, of confirmed members of the young open cluster Gamma Velorum, with the aim of deriving general cluster properties such as the IMF. We used all available spectroscopic membership indicators within the Gaia-ESO public archive together with literature photometry and X-ray data and, for each method, we derived the most complete list of candidate cluster members. Then, we considered photometry, gra…

Generation and characterization of 06-THz polarization domain-wall trains in an ultralow-birefringence spun fiber

2007

Polarization domain-wall (PDW) trains have been generated at a repetition rate of 0.6 THz in an ultralow-birefringence spun optical fiber and measured by use of an adapted frequency-resolved optical gating technique. Characterization of the intensity and the phase of the PDW train shows complete switching between adjacent domains of counterrotating circular polarizations and directly confirms predictions based on numerical simulations of the incoherently coupled nonlinear Schrödinger equations.

University of Palermo: Exploiting the Optical Quadratic Nonlinearity of Zinc-Blende Semiconductors for Guided-Wave Terahertz Generation: A Material C…

2012

Content synopsis of the following paper: Matteo Cherchi, Alberto Taormina, Alessandro C. Busacca, Roberto L. Oliveri, Saverio Bivona, Alfonso C. Cino, Salvatore Stivala, Stefano Riva Sanseverino, and Claudio Leone, "Exploiting the Optical Quadratic Nonlinearity of Zinc-Blende Semiconductors for Guided-Wave Terahertz Generation: A Material Comparison", IEEE Journal of Quantum Electronics, Vol. 46, N. 3, March 2010

Art Painting Testing with Terahertz Pulse and Frequency Modulated Continuous Wave

2017

Paintings of individuals or collections undergo aging over time. The work of art restorers consists of repairing these defects using techniques that respect the history of the work. Ultraviolet, infrared and visible light and X-rays are well known techniques for analyzing these defects, but Terahertz is also increasingly used. Several works have shown that it is possible to detect hidden layers and various defects via terahertz pulses. In a previous work, we have shown that it is possible to use terahertz radiation to detect defects in the context of a restoration of a painting with a speed increase compared to time domain imaging.

Imprinting the complex dielectric permittivity of liquids into the spintronic terahertz emission

2021

We report an approach in time-domain terahertz (THz) spectroscopy for measuring the dielectric response of liquids based on inherent properties of spintronic THz emitters (STEs). The THz electric field radiated from the STE is inversely proportional to the sum of the complex refractive indices of the media surrounding the thin metallic stack of the STE and the stack's conductivity. We demonstrate that by bringing a liquid in contact with the emitter, its complex refractive index and accordingly its dielectric response are imprinted into the radiated electromagnetic field from the emitter. We use water as the test liquid and ascertain its dielectric loss and permittivity in the range of ∼0.…

Schallreaktionen bei Nachtfaltern

1949

Numerous Noctuides and Geometrides show quite mistakable reactions upon sound stimulations ranging from 10,000 to 20,0000 vib/sec (Hertz). The lowest limit range of perception seems to lie at 40,000 up to 80,000 vib/sec. The reactions of sitting or walking animals are instant movements of flight or catalepsy. Flying animals try evasion or stop their flight at once. Sleeping animals can not be roused by sound stimulation. There are no sound reactions if both tympani are pierced. The Noctuides and Geometrides seem to perceive the supersonic echolocation cries of bats by aid of their tympanal organs.