Split-aperture laser pulse compressor design tolerant to alignment and line-density differences

This paper was published in Optics Letters and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://dx.doi.org/10.1364/OL.33.001902 Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law

VISUAL-CC system uncovers the role of GSK3 as an orchestrator of vascular cell type ratio in plants

The phloem transports photosynthetic assimilates and signalling molecules. It mainly consists of sieve elements (SEs), which act as "highways" for transport, and companion cells (CCs), which serve as "gates" to load/unload cargos. Though SEs and CCs function together, it remains unknown what determines the ratio of SE/CC in the phloem. Here we develop a new culture system for CC differentiation in Arabidopsis named VISUAL-CC, which almost mimics the process of the SE-CC complex formation. Comparative expression analysis in VISUAL-CC reveals that SE and CC differentiation tends to show negative correlation, while total phloem differentiation is unchanged. This varying SE/CC ratio is largely dependent on GSK3 kinase activity. Indeed, gsk3 hextuple mutants possess many more SEs and fewer CCs, whereas gsk3 gain-of-function mutants partially increase the CC number. Taken together, GSK3 activity appears to function as a cell-fate switch in the phloem, thereby balancing the SE/CC ratio. Tamaki et al. develop VISUAL-CC to study SE-CC (sieve elements-companion cells) complex formation. They show that the balance in the SE/CC ratio is dependent on GSK3 activity using different genetic backgrounds. Their work provides insights on the role of GSK3 as a cell-fate switch in the phloem.Peer reviewe

Pulse compression and beam focusing with segmented diffraction gratings in a high-power chirped-pulse amplification glass laser system

This paper was published in Optics Letters and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://dx.doi.org/10.1364/OL.35.001783 Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law

X-ray harmonic comb from relativistic electron spikes

X-ray devices are far superior to optical ones for providing nanometre spatial and attosecond temporal resolutions. Such resolution is indispensable in biology, medicine, physics, material sciences, and their applications. A bright ultrafast coherent X-ray source is highly desirable, for example, for the diffractive imaging of individual large molecules, viruses, or cells. Here we demonstrate experimentally a new compact X-ray source involving high-order harmonics produced by a relativistic-irradiance femtosecond laser in a gas target. In our first implementation using a 9 Terawatt laser, coherent soft X-rays are emitted with a comb-like spectrum reaching the 'water window' range. The generation mechanism is robust being based on phenomena inherent in relativistic laser plasmas: self-focusing, nonlinear wave generation accompanied by electron density singularities, and collective radiation by a compact electric charge. The formation of singularities (electron density spikes) is described by the elegant mathematical catastrophe theory, which explains sudden changes in various complex systems, from physics to social sciences. The new X-ray source has advantageous scalings, as the maximum harmonic order is proportional to the cube of the laser amplitude enhanced by relativistic self-focusing in plasma. This allows straightforward extension of the coherent X-ray generation to the keV and tens of keV spectral regions. The implemented X-ray source is remarkably easily accessible: the requirements for the laser can be met in a university-scale laboratory, the gas jet is a replenishable debris-free target, and the harmonics emanate directly from the gas jet without additional devices. Our results open the way to a compact coherent ultrashort brilliant X-ray source with single shot and high-repetition rate capabilities, suitable for numerous applications and diagnostics in many research fields

High Power Laser Facilities at the Kansai Photon Science Institute

At the Kansai Photon Science Institute (KPSI, Kyoto, Japan), there are three unique high-power laser facilities. Here, we introduce the features of each facility and some experimental studies, which will be useful to users as a reference

Simple synchronization technique of a mode-locked laser for Laser-Compton scattering Gamma-ray source

We propose a simple and effective synchronization technique between a reference electrical oscillator and a mode-locked laser for a narrowband picosecond Laser-Compton scattering Gamma-ray source by using a commercial-based 1-chip frequency synthesizer, which is widely used in radio communication. The mode-locked laser has been successfully synchronized in time with a jitter of 180 fs RMS for 10 Hz - 100 kHz bandwidth. A good stability of 640 uHz at 80 MHz repetition rate for 10 hours operation has also been confirmed. We discuss in detail the design and performance of this technique (in terms of timing jitter, stability, and validity)

High Power Laser Facilities at the Kansai Photon Science Institute

At the Kansai Photon Science Institute (KPSI, Kyoto, Japan), there are three unique high-power laser facilities. Here, we introduce the features of each facility and some experimental studies, which will be useful to users as a reference