Direct shaping of picosecond high energy deep ultraviolet pulses

We demonstrate temporally shaped pulses in the deep ultraviolet spectral range (270nm) with energies up to 37μJ using an efficient prism stretcher and an acousto-optic programmable dispersive filter (AOPDF) applied directly in the UV. The scheme allows for arbitrary phase and amplitude shaping of picosecond UV pulses at high energy in a simple and efficient wa

Field-driven femtosecond magnetization dynamics induced by ultrastrong coupling to THz transients

Controlling ultrafast magnetization dynamics by a femtosecond laser is attracting interest both in fundamental science and industry because of the potential to achieve magnetic domain switching at ever advanced speed. Here we report experiments illustrating the ultrastrong and fully coherent light-matter coupling of a high-field single-cycle THz transient to the magnetization vector in a ferromagnetic thin film. We could visualize magnetization dynamics which occur on a timescale of the THz laser cycle and two orders of magnitude faster than the natural precession response of electrons to an external magnetic field, given by the Larmor frequency. We show that for one particular scattering geometry the strong coherent optical coupling can be described within the framework of a renormalized Landau Lifshitz equation. In addition to fundamentally new insights to ultrafast magnetization dynamics the coherent interaction allows for retrieving the complex time-frequency magnetic properties and points out new opportunities in data storage technology towards significantly higher storage speed.Comment: 25 page

Can Energetic Terahertz Pulses Initiate Surface Catalytic Reactions on the Picosecond Time Scale?

In preparation for picosecond pump-probe experiments at the SwissFELX-ray laser facility, the feasibility of collectively initiating surface chemical reactions using energetic pulses of terahertz radiation is being tested

NOTAS E RESENHAS

COBERTURA VEGETAL, POLUIÇÃO AÉREA E DESLIZAMENTOS NA SERRA DO MAR – Helmut TROPPMAIR e Maria Eugênia M. C. FERREIRA. A ECONOMIA POLÍTICA DO COMPLEXO AGROINDUSTRIAL BRASILEIRO (Notas Básicas para Elaboração de um Programa de Pesquisa) - Geraldo MULLER SISTEMAS DA SUPERFÍCIE TERRESTRE - Antonio CHRISTOFOLETTI GEOMORFOLOGIA DINÂMICA, AMBIENTAL E PALEOECOLOGIA - Antonio CHRISTOFOLETTI ANÁLISE, MONITORIAMENTO E PREVISÃO EM HIDROLOGIA - Antonio CHRISTOFOLETTI ENSINO DA GEOGRAFIA - Antonio CHRISTOFOLETTI ATLAS NACIONAL DO BRASIL - REGIÃO NORDESTE - Miguel Cezar SANCHEZ INTRODUÇÃO À BIODETERIORAZÃO - Myrian Cecilia ROLIM PROCHNOW REFLORESTAMENTO E IMPACTOS AMBIENTAIS - Maria Juraci ZANI DOS SANTOS FORMA URBANA E A NOVA TECNOLOGIA - Pompeu FIGUEIREDO DE CARVALHO O CAPITAL FINANCEIRO E O MERCADO IMOBILIÁRIO DE ESCRITÓRIOS - Pompeu FIGUEIREDO DE CARVALHO O PODER DA BUROCRACIA – R. BATLEY DIALÉTICA DO CONCRETO - Aldomar Arnaldo RUCHERT INTELIGÊNCIA ARTIFICIAL - João Francisco DE ABREU SISTEMAS DE INFORMAÇÃO PARA PLANEJAMENTO REGIONAL - João Francisco DE ABREU ANÁLISE DOS FLUXOS DE MIGRAÇÃO - João Francisco DE ABREU MODELOS PROJETIVOS DA POPULAÇÃO REGIONAL - João Francisco DE ABREU REPRESENTAÇÃO GRÀFICA DAS INFORMAÇÕES QUANTITATIVAS - João Francisco DE ABREU A CULTURA DO ARROZ - Ana Tereza CACERES CORTEZ MORAES O OCEANO MIOCÊNICO - Reinaldo José BERTINI PROGRESS IN PHYSICAL AND IN HUMAN GEOGRAPHY 1985-1986 - Antonio CHRISTOFOLETTI CONCEITOS E TÉCNICAS EM GEOGRAFIA - Antonio CHRISTOFOLETTI GEOGRAFIA ECONÔMICA DA HÚNGRIA - Antonio CHRISTOFOLETTI PRAGAS E VENENOS: AGROTÓXICOS NO BRASIL E NO TERCEIRO MUNDO - Lígia Celoria POLTRONIÉRI O ESCÂNDALO DAS SEMENTES: O DOMÍNIO NA PRODUÇÃO DE ALIMENTOS - Lígia Celoria POLTRONIÉR

High field broadband THz generation in organic materials

Organic salt crystals, e.g. DAST, OH1, and DSTMS, pumped by ultra-short infrared laser are efficient THz emitters. We review our latest results on the generation in organic crystals of THz single-cycle transients with field strength of 1.5 MV/cm. The energy conversion reaches 2% with photon conversion efficiency up to 200%. THz radiation produced in such crystals offers excellent beam propagation properties and can be focused down to diffraction limited spot size in order to realize the highest field. This source covers the full spectral range between 0.1 and 10 THz. Further, we discuss the possibility to control the absolute phase and the polarity of the THz field

Intense THz radiation produced in organic salt crystals for high-field applications

Organic stilbazolium salt crystals pumped by intense, ultrashort mid-infrared laser have been investigated for efficient THz generation by optical rectification. In this paper we present our latest results in view of the generation of single-cycle and high-field THz transient in the THz gap (0.1-10 THz). The organic rectifiers like DAST, OH1 and DSTMS combine extremely large optical susceptibility with excellent velocity matching between the infrared pump and the THz radiation. Our simple collinear conversion scheme provides THz beams with excellent focusing properties and single cycle electric field larger than 1.5 MV/cm and magnetic field strength beyond 0.5 Tesla. The source can potentially cover the full THz gap at field strength which is barely provided by other THz sources. The THz pulse is carrier-envelope phase stable and the polarity of the field can be easily inverted. © 2013 Copyright SPIE

Multi-octave MV/cm pulses filling the THz gap

Single-cycle THz pulses with electric field strength of MV/cm are required for wide range of applications from physics to biology and medicine [1]. Presently, high fields are still challenging to produce in the THz gap (0.1-10 THz) where important condensed matter resonances are expected (i.e. magnons, phonons, electromagnons). We present our latest results on the generation of 1.5 MV/cm electric field in this frequency range. Broadband THz pulse are achieved by optical rectification (OR) in large organic crystals such as DAST, OH1 and DSTMS [2-4]. These materials present an OR susceptibility one order of magnitude larger than the room-temperature inorganic nonlinear crystals. The THz radiation is phase-matched with IR pump allowing for photon conversion larger than 200% and pulse energy of tens of μJ. The beam can be focused to nearly diffraction-limit for the realization of the highest field. For 0.5 mm thick DSTMS, electric field larger than 1.5 MV/cm is achieved in 350 μm FWHM spot. The electro-optical sampling trace, the corresponding 5-octave spectrum (0.15-5 THz) and the THz focus are shown in Fig. 1. Fields of the 1 MV/cm are obtained also in DAST and OH1. We show that proper dispersive materials can be used to control absolute phase of the THz transient without significant losses. © 2013 IEEE