Search results for "THZ"
showing 9 items of 19 documents
Counter-propagating frequency mixing with Terahertz waves in diamond
2013
Frequency conversion by means of Kerr nonlinearity is one of the most common and exploited nonlinear optical processes in the UV, visible, IR, and mid-IR spectral regions. Here we show that wave mixing of an optical field and a terahertz wave can be achieved in diamond, resulting in the frequency conversion of the terahertz radiation either by sum- or difference-frequency generation. In the latter case, we show that this process is phase matched and most efficient in a counterpropagating geometry.
THz spectroscopy studies on proteins: exploring collective modes of amyloid fibrils
2013
ULTRA-BROADBAND COHERENT DETECTION OF TERAHERTZ PULSES VIA CMOS-COMPATIBLE SOLID-STATE DEVICES
Il presente lavoro di tesi presenta e dimostra una tecnica innovativa e completamente integrata dedita alla rilevazione coerente di radiazioni a frequenze Terahertz (THz), cioè di onde elettromagnetiche il cui contenuto frequenziale cade convenzionalmente nella finestra spettrale compresa tra 0.1-10x1012 Hz. Tale tecnica è stata battezzata col nome di solid-state-biased coherent detection (SSBCD), dal momento che essa sfrutta le proprietà di un mezzo a stato solido e consente di ricostruire simultaneamente l’informazione sulla fase e sull’ampiezza degli impulsi THz, anche nel caso in cui quest’ultimi siano dotati di spettri a banda cosiddetta “ultra larga” (> 10 THz). Tale metodo di rivelaz…
Dependence of Terahertz Emission and Detection in Photoconductive Antennas on Laser Parameters
In this study, we employ a standard Terahertz time-domain spectroscopy (THz-TDS) setup based on two photoconductive antennas (PCAs) for THz radiation generation and detection. The characterization of the emission and detection performance as a function of the input pulse wavelength and bandwidth is performed.
THz spectroscopy study of amyloid fibrils
2013
In suitable conditions proteins can modify their native conformation and associate to form aggregates with different morphologies in dependence on the external physico-chemical conditions. This phenomenon, one of the most challenging in life sciences, is associated with widely diffused pathologies such as Alzheimer’s, Parkinson’s and Creutzfeldt-Jacob’s diseases. Of particular relevance are ordered elongated aggregates with highly organized patterns of hydrogen-bonds, known as amyloid fibrils. While much biological and structural information are available about amyloids, and in spite of the fundamental paradigm of structure-dynamics-function relation in proteins, much less is known about th…
Numerical Model of THz sources and detectors based on Optical Rectification and Electro-Optic Sampling
2013
A model describing a laser based set-up for wideband THz generation and detection is presented. Particular attention is focused on the main broadband phenomena, which occur when THz radiations have to be handled.
Exact Reconstruction of Sub-wavelength THz Source Profile via Combination of Knife-edge Technique and Time-domain Spectroscopy
2013
Strongly Coupled Coherent Phonons in Single-Layer MoS 2
2019
We present a transient absorption setup combining broadband detection over the visible-UV range with high temporal resolution ($\sim$20fs) which is ideally suited to trigger and detect vibrational coherences in different classes of materials. We generate and detect coherent phonons (CPs) in single layer (1L) MoS$_2$, as a representative semiconducting 1L-transition metal dichalcogenide (TMD), where the confined dynamical interaction between excitons and phonons is unexplored. The coherent oscillatory motion of the out-of-plane $A'_{1}$ phonons, triggered by the ultrashort laser pulses, dynamically modulates the excitonic resonances on a timescale of few tens fs. We observe an enhancement by…