Volume Bragg Grating assisted broadband tunability and spectral narrowing of Ti:Sapphire oscillators

A widely tunable, narrow band Ti:Sapphire oscillator is reported. Tunability and spectral narrowing were achieved by use of a volume Bragg grating in the cavity. Tunability was observed from 785 nm to 852 nm while maintaining a spectral linewidth less than 10 pm with essentially no spectral jitter. Oscillation on only 2 longitudinal modes is also reported at 852 nm with the grating at normal incidence providing similar to 200 mW output power

Strong-field physics with mid-IR fields

Strong-field physics is currently experiencing a shift towards the use of mid-IR driving wavelengths. This is because they permit conducting experiments unambiguously in the quasi-static regime and enable exploiting the effects related to ponderomotive scaling of electron recollisions. Initial measurements taken in the mid-IR immediately led to a deeper understanding of photo-ionization and allowed a discrimination amongst different theoretical models. Ponderomotive scaling of rescattering has enabled new avenues towards time resolved probing of molecular structure. Essential for this paradigm shift was the convergence of two experimental tools: 1) intense mid-IR sources that can create high energy photons and electrons while operating within the quasi-static regime, and 2) detection systems that can detect the generated high energy particles and image the entire momentum space of the interaction in full coincidence. Here we present a unique combination of these two essential ingredients, namely a 160\~kHz mid-IR source and a reaction microscope detection system, to present an experimental methodology that provides an unprecedented three-dimensional view of strong-field interactions. The system is capable of generating and detecting electron energies that span a six order of magnitude dynamic range. We demonstrate the versatility of the system by investigating electron recollisions, the core process that drives strong-field phenomena, at both low (meV) and high (hundreds of eV) energies. The low energy region is used to investigate recently discovered low-energy structures, while the high energy electrons are used to probe atomic structure via laser-induced electron diffraction. Moreover we present, for the first time, the correlated momentum distribution of electrons from non-sequential double-ionization driven by mid-IR pulses.Comment: 17 pages, 11 figure

Imaging an aligned polyatomic molecule with laser-induced electron diffraction

Laser-induced electron diffraction is an evolving tabletop method, which aims to image ultrafast structural changes in gas-phase polyatomic molecules with sub-{\AA}ngstr\"om spatial and femtosecond temporal resolution. Here, we provide the general foundation for the retrieval of multiple bond lengths from a polyatomic molecule by simultaneously measuring the C-C and C-H bond lengths in aligned acetylene. Our approach takes the method beyond the hitherto achieved imaging of simple diatomic molecules and is based upon the combination of a 160 kHz mid-IR few-cycle laser source with full three-dimensional electron-ion coincidence detection. Our technique provides an accessible and robust route towards imaging ultrafast processes in complex gas phase molecules with atto- to femto-second temporal resolution.Comment: 16 pages, 4 figure

[Book Review] OMURA, Yutaka. 2008. The fundamental study regarding the history of prehistoric archaeology in Japan:The study of Sugao Yamanouchi and those around him Rokuichisyobo, pp.1-215.

大村 裕著『日本先史考古学史の基礎研究-山内清男の学問とその周辺の人々-』A5判 215頁,六一書房,2008年5月刊,本体価格2,500円+税本稿は大村裕氏『日本先史考古学史の基礎研究-山内清男の学問とその周辺の人々-』の書評である。著者はまず日本先史考古学の基盤を築いた山内清男を基軸として、その周囲に展開した研究者の活動を対象としつつ、わが国の先史考古学研究史の再検討を試みる。その中でとくに山内の先人として、その学問形成に直接的な影響を与えたと想定される研究者についてやや予察的な検討を行っている。これは、隣接する学問分野(人類学・歴史学・民俗学・社会学など)の方法論を採り入れたものであり、今後とも斯学に新たな視点を提供していくものと思われる。また、著者は研究史的な検証と併行して、山内の学問的体系とは如何なるものなのかということについても考究した。様々な資料を駆使して、山内が残した論文を詳細に読み解いていく手法は堅実で説得力がある。とくに従来、余りにも素朴に考えられてきた「繩紋」という用語について、原典の丹念な読解によって、その理解に一入の深化を与えたと言える。また文様帯系統論についても、その発想の根源にある生物学的な知見に注目し、難解と言われてきた理論の理解を援ける視点を提供した。さらに、これらを総合し、著者自身が直面する学問的課題に対処するための方法を実際の資料に即して展開したことは、山内の学問に真摯に学んだ研究者のものとして、後学にも資するところ大であると思われる

High Performances In Continuous-Wave And Q-Switch Operation Of A Narrow Linewidth Nd: Yvo4 Oscillator Using A Volume Bragg Grating

A quasi-single-longitudinal mode Nd:YVO4 oscillator providing up to 11 W CW is presented. In Q-switched regime, up to 1.2 mJ output energy with spectral linewidth narrower than 20 pm at 1kHz repetition rate were obtained. © 2010 Optical Society of America

Current Status Of The Heracles, A Millijoule Level, Multi Khz, Few-Cycle, And Cep Stabilized Opcpa System

A cryogenic-cooling free, few-cycle, carrier-envelope-phase stabilized OPCPA designed to operate at repetition rates as high as 25 kHz with millijoule level energy is presented. Motivation, design issues and current state of the system are reported. © 2010 Optical Society of America

A compact quasi-single-cycle, phase stabilized laser system

A table-top OPCPA laser system designed to produce energy beyond 1.5 mJ at repetition rates up to 10 kHz with pulse duration shorter than 10 fs and featuring carrier-envelope phase stabilization is reported. ©2010 IEEE

Current Status Of The Heracles, A Millijoule Level, Multi Khz, Few-Cycle, And Cep Stabilized Opcpa System

A cryogenic-cooling free, few-cycle, carrier-envelope-phase stabilized OPCPA designed to operate at repetition rates as high as 25 kHz with millijoule level energy is presented. Motivation, design issues and current state of the system are reported. © 2010 Optical Society of America

A Compact Quasi-Single-Cycle, Phase Stabilized Laser System

A table-top OPCPA laser system designed to produce energy beyond 1.5 mJ at repetition rates up to 10 kHz with pulse duration shorter than 10 fs and featuring carrier-envelope phase stabilization is reported. ©2010 IEEE

A Joule-Class, Tem00 Spatial Profile, Narrow-Linewidth Laser System

A Joule-class, narrow-linewidth amplifier line delivering 20 ns pulses with a TEM00 spatial profile is presented. A Qswitched Nd:YAG oscillator with an intra-cavity volume Bragg grating (VBG) is used to seed the amplifier line. A series of flashlamp-pumped Nd:YAG amplifiers consisting of a double-pass and two single-pass amplifiers boost the energy of the 21 ns pulses to 480 mJ. The presented amplifier line will be used for fundamental studies including remote Raman spectroscopy and ns filamentation. © 2011 SPIE