Matthew Rever

Femtosecond Yb-fiber chirped-pulse-amplification system based on chirped-volume Bragg gratings

A 100 W amplified (75 W compressed) femtosecond (650 fs) Yb-fiber chirped-pulse-amplification system is demonstrated using broadband chirped-volume Bragg gratings (CVBGs) for the stretcher and compressor. With a 75% compression efficiency, the CVBG-based compressor exhibits an excellent average power handling capability and indicates the potential for further power scaling with this compact and robust technology.

Mechanism and Control of High-Intensity- Laser-Driven Proton Acceleration

We discuss the optimization and control of laser‐driven proton beams. Specifically, we report on the dependence of high‐intensity laser accelerated proton beams on the material properties of various thin‐film targets. Evidence of star‐like filaments and beam hollowing (predicted from the electrothermal instability theory) is observed on Radiochromic Film (RCF) and CR‐39 nuclear track detectors. The proton beam spatial profile is found to depend on initial target conductivity and target thickness. For resistive target materials, these structured profiles are explained by the inhibition of current, due to the lack of a return current. The conductors, however, can support large propagating currents due to the substantial cold return current which is composed of free charge carriers in the conduction band to neutralize the plasma from the interaction. The empirical plot shows relationship between the maximum proton energy and the target thickness also supports the return current and target normal sheath accel...

32 W femtosecond Yb-fiber CPA system based on chirped-volume-Bragg-gratings

Femtosecond (~670 fs) fiber-CPA at 1.063 mum is demonstrated using broadband chirped-volume-Bragg-gratings for pulse stretching and compression. 32 W recompressed pulses are achieved corresponding to a 75% compression efficiency.

Generation of hard X-rays using an ultrafast fiber laser system

We report the first hard X-ray source driven by a femtosecond fiber laser. The high energy fiber CPA system incorporated a 65mum LMA fiber amplifying stage which provided 300-fs recompressed pulses and diffraction limited beam quality with M(2) < 1.07. A deformable mirror was used to optimize the wavefront and the spot size was focused down to 2.3 mum with an f/1.2 paraboloidal mirror. 50muJ was deposited on the nickel target with 2x10(15)-W/cm(2) focal intensity and a distinctive Ni K(alpha)-line (7.48 keV) emission was measured with 5x10(-8) energy conversion efficiency.

200 fs, 50 W fiber-CPA system based on chirped-volume-Bragg-gratings

Record-short pulses of 200fs have been obtained from a power-scalable-Yb-fiber-CPA system that uses chirped-volume-Bragg-gratings for the stretcher and compressor. The power was scaled up to 50W with a corresponding 33W of compressed power.

100 W Femtosecond Yb-Fiber CPA System based on Chirped-Volume-Bragg-Gratings

100 W amplified (75 W compressed) femtosecond (∼700 fs) Yb-fiber CPA system is demonstrated using broadband chirped-volume-Bragg-gratings (CVBG) as the stretcher and compressor. With 75% compression efficiency, the CVBG based compressor exhibits an excellent average power handling capability and indicates potential for further power scaling with this compact compressor technology.

200W, 350fs fiber CPA system enabled by chirped-volume-Bragg-gratings and chirally-coupled-core fiber technology (Withdrawal Notice)

This paper was presented at the SPIE conference indicated above and has been withdrawn from publication at the request of the authors.

Femtosecond Yb-Fiber CPA System Based on Chirped-Volume-Bragg-Gratings

Femtosecond (~670 fs) fiber-CPA at 1.063 mum is demonstrated using broadband chirped-volume-Bragg-gratings for pulse stretching and compression. 32 W recompressed pulses are achieved corresponding to a 75% compression efficiency.

Observation of Relativistic Cross-Phase Modulation in High Intensity Laser-Plasma Interactions

We report a novel nonlinear optical phenomena, relativistic cross-phase modulation between Raman light and a high intensity laser pulse in an underdense plasma. The experimental spectra compared well with calculations from a proposed theoretical model

Evidence of Ionization Blue Shift Seeding of Forward Raman Scattering

We report on the results of spectroscopic experiments that were conducted by focusing an intense ultra‐short laser pulse onto a helium gas target. The scattered light from the interaction region was measured spectrally and spatially from various directions as a function of laser intensity and plasma density. The experimental data showed that forward Stimulated Raman Scattering (SRS) was sensitive to the focus position of laser relative to the nozzle. Together with the plasma channel that was imaged by a CCD camera, the measurements indicate that SRS is seeded by the ionization blue‐shifted light. The cross‐phase modulation between the SRS and laser beam was also observed in the experiment.