Contrast Improvement of Relativistic Few-Cycle Light Pulses

Surface-reflection-initiated pulse-contrast degradation in an optical parametric chirped-pulse amplifier

“…Pulse-contrast of high-peak-power laser pulses has been a major concern in applications such as high field physics [1]. Undesired laser light in the form of pedestal or pre-pulses could trigger an early ionization of the target before the main pulse arrives and alter the interaction properties detrimentally.…”

“…Multi-petawatt laser systems in the future will have even more demanding expectations for pulse-contrast (e.g., up to 10 12 -10 14 ), although pulse-contrast usually degrades with the increase of operating power. Nowadays, contrast of 10 9 -10 10 within tens of picoseconds before the main pulse is almost the highest achievable level in high-power laser systems either based on chirped-pulse amplification (CPA) or optical parametric chirped-pulse amplification (OPCPA) techniques [1][2][3][4][5][6][7][8]. The mechanisms for pulse-contrast degradation have been widely studied.…”

“…The mechanisms for pulse-contrast degradation have been widely studied. Except the background noises such as amplified spontaneous emission (ASE) [1] or optical parametric fluorescence (OPF) [9,10], which are always present in optical amplifiers, almost all of other proven contrast degradation mechanisms are directly or indirectly associated with modulations of the spectral amplitude or spectral phase. Spectral clipping from the acceptance of stretcher [2], pump-noise transfer [11][12][13] and the presence of weak post-pulses [14,15] are typical sources of spectral amplitude modulations.…”

“…Beyond that, further cleaning of the amplified high-power pulse based on certain peak-switching effect intrinsic to intense laser interacting with matter has also been proposed. Such techniques include plasma mirror (PM) [1] and second-harmonic generation of high-intensity lasers [25].…”

Ultrarövid, ultraibolya lézerimpulzusok és magas harmonikusok diagnosztikája

“…Az elmúlt évtizedek során ehhez különböző időbeli kontrasztnövelő eljárásokat fejlesztettek ki, mint például a telítődő abszorber alkalmazása, a mag-impulzus energiájának növelése vagy a kereszt-polarizált hullám keltése [43]. A nagy intenzitású lézerimpulzusok esetén a leggyakoribb kontrasztnövelő eljárás a plazmatükör technika.…”