S. Coe

X‐ray spectroscopy of hot solid density plasmas produced by subpicosecond high contrast laser pulses at 1018–1019 W/cm2

Analysis is presented of K‐shell spectra obtained from solid density plasmas produced by a high contrast (1010:1) subpicosecond laser pulse (0.5 μm) at 1018–1019 W/cm2. Stark broadening measurements of He‐like and Li‐like lines are used to infer the mean electron density at which emission takes place. The measurements indicate that there is an optimum condition to produce x‐ray emission at solid density for a given isoelectronic sequence, and that the window of optimum conditions to obtain simultaneously the shortest and the brightest x‐ray pulse at a given wavelength is relatively narrow. Lower intensity produces a short x‐ray pulse but low brightness. The x‐ray yield (and also the energy fraction in hot electrons) increases with the laser intensity, but above some laser intensity (1018 W/cm2 for Al) the plasma is overdriven: during the expansion, the plasma is still hot enough to emit, so that emission occurs at lower density and lasts much longer. Energy transport measurements indicate that approximate...

Amplification of 1 ps pulses at 1.053 μm in a Ti:Al2O3 regenerative amplifier

Abstract We demonstrate the operation of a Ti:Al2O3 regenerative amplifier tunable around 1 μm. Gains up to 108 at 1.053 μm without any spectral narrowing are obtained. This amplifier is designed for use in terawatt picosecond lasers.

Time-resolved kiloelectron-volt spectroscopy of ultrashort plasmas.

We describe a technique for spectrally and temporally resolving the kilo-electron-volt emission fromultrashort plasmas produced from solid targets with a tabletop terawatt 400-fs laser. The firsttime-resolved Al spectra (near 8 Å) obtained with a 2-ps time resolution are presented. The results clearly demonstrate that the resonance emission width decreases as the plasma density increases. The ultrafast K(α) emission component is also measured in our experimental conditions.

Characteristics of an actively mode-locked 2-psec Ti:sapphire laser operating in the 1-μm wavelength regime

We examine the performance of an actively mode-locked Ti:sapphire laser operating in the 1-microm wavelength regime. Pulse durations of 1.7 psec are produced with an average output power of 400 mW. With the use of external dispersion compensation this pulse width has been further reduced to 850 fsec.

An alexandrite pumped Nd:glass regenerative amplifier for chirped pulse amplification

Abstract An alexandrite pumped, Nd:glass regenerative amplifier is demonstrated. This amplifier has been used with chirped pulse amplification to produce millijoule, picosecond pulses. Using this technique the overall gain bandwidth of glass systems can be conveniently extended, as demonstrated here. This method is also applicable to other broadband materials such as Cr:LiSrAlF 6 .

Ultrafast x-ray emission from ultrashort plasmas

We present recent results of our effort to develop an efficient, user-friendly, table-top ultrafast X-ray source. The factors affecting the duration and the intensity of the X-ray emission in the keV range are studied. Time-dependent calculation of the atomic physics coupled to a Fokker- Planck code is used for a quantitative analysis of the experimental results.

Long-range, high-resolution laser radar

Abstract A high energy, chirped pulse laser was used to demonstrate long range, high resolution radar. A broadband nanosecond chirped pulse propagated to a target, and upon compression sub-millimeter surface resolution was obtained. This technique avoided the nonlinear effects in air that were seen when a picosecond pulse propagated to the target.

Spectroscopic analysis of short-pulse laser-produced plasmas

Experimental spectra of hot dense plasmas of aluminium produced by the interaction of a subpicosecond laser with solid targets at 10 16 and 5 × 10 17 W/cm 2 are analyzed and discussed. A detailed analysis of the K -shell spectra is given through time-dependent calculations of atomic physics postprocessed to Fokker-Planck calculations of the laser-matter interaction. The non-Maxwellian character of the electron distribution function is shown. An evaluation of the electronic density and of the ion temperature 7 i will be presented through Stark line broadening calculations. An X-ray spectrum from a Tantalum target also will be presented along with a preliminary interpretation.

High-efficiency frequency doubling of ultra-intense Nd:glass laser pulses

Efficient second harmonic conversion (70 - 80%) using Type II and Type I crystals is demonstrated with 400-fs, 1.053-micrometers laser pulses at intensities up to several hundreds of GW/cm2. The experimental results generally agree with the predictions of the code MIXER. For the Type II predelay scheme, evidence is obtained of pulse shortening down to approximately 100 fs.

Laser plasma interactions at electron-relativistic laser intensities

A review is given (intended for the non-expert) of the field of ultrashort laser pulses at ultra high intensities and their interactions with plasmas. The review covers progress and basic concepts for theory, modelling and experiments, with emphasis on the background aspects, the basic experimental considerations and some possible applications.