Dear Colleagues,

In the past few decades, the remarkable progress in the generation of intense electromagnetic fields up to the PW range was driven by the chirped pulse amplification (CPA) technique using IR solid state (Ti:sapphire) lasers. Short-pulse UV excimer lasers can produce high-intensity fields even at a moderate power level.

Previously, the performance of large-scale laser systems was mainly characterized by their maximum power or brightness. Recently, increased interest has been dedicated to the intensity contrast of such systems. A great amount of experimentation confirmed that pre-pulses of 10⁷-10⁸ W/cm² intensity can change laser–matter interactions considerably. Considering the 10²⁰-10²³ W/cm² focused intensity of present laser systems, the necessary intensity contrast is in the 10¹²-10¹⁶ regime.

Several techniques have been developed, providing 10¹⁰ and 10¹² temporal contrast on the ns scale. However, an inherent shortcoming of CPA based systems is that a coherent pedestal in the ps temporal vicinity of the main pulse still remains.

In contrast to solid-state CPA systems, short-pulse UV lasers use direct amplification; therefore, the only source of the temporal background is the ASE, which, however, grows very rapidly.

In both systems, contrast improvement techniques are needed to be applied in the end (or preferably after) the amplifier chain. This necessitates the use of energy-scalable pulse cleaning methods, such as the plasma mirror technique, or the recently introduced nonlinear Fourier filtering (NFF).

Implementation/further improvement of these techniques – including experimental testing of their wavelength and energy-scalability – could open new perspectives on the achievable temporal contrast of high-power laser systems.

Applied Sciences invites papers for a Special Issue on “The Temporal Contrast Issue of High Power/High-Brightness Lasers”, including the measurement, the theoretical and experimental study of the temporal noise of large-scale laser systems.

Papers are welcome dealing with different aspects of the design of high-power laser systems and pulse cleaning arrangements, with particular emphasis on the achievable temporal contrast and on the relevant feasibility.

Dr. Sándor Szatmári
Guest Editor

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• Spatial and temporal intensity contrast
• High-power (high-brightness) laser systems
• CPA systems
• Double CPA arrangement
• Coherent temporal pedestal
• Plasma mirror technique
• Cross-polarized wave generation (XPW) technique
• Short pulse excimer systems
• Frequency conversion
• Active spatial filtering
• Nonlinear Fourier filtering (NFF)
• Energy-scalability.