Generation of High-energy Few-cycle Pulses by Filament Compression

Abstract

Recent developments in intense few-cycle laser pulse generation have triggered many breakthrough experiments in high-field science and have paved the way toward time-resolved spectroscopy on the attosecond (10−18 s) timescale []–[]. In particular, it was shown that intense driving pulses with only two to three reproducible field oscillations are a prerequisite for controlling the generation of isolated attosecond pulses by high-order harmonic generation in rare gases []. Until recently, intense few-cycle pulses could only be obtained through spectral broadening of amplified femtosecond laser pulses in a gas-filled, hollow-core fiber, followed by chirped mirror compression [],[]. Although successful, the hollow-fiber compression technique limits the pulse energy available for experiments to a few hundred microjoules. However, exploring laser-matter interactions in the relativistic intensity (> 1018 W · cm−2) regime requires significantly higher focused pulse energies []. When confined in space and time to a volume of a few λ3, femtosecond laser pulses can reach relativistic intensities with pulse energies close to 1 mJ []. This leads to strong nonlinear laser-plasma interactions such as relativistic reflection, deflection, and compression of a few-cycle femtosecond pulse down to the attosecond regime with an efficiency up to 10% []. One major requirement for this generation technique is the availability of carrier-envelope phase (CEP) stabilized few-cycle pulses with microjoule energy. We therefore explored a novel scheme for high-energy, CEP-stable few-cycle pulse generation, which is easy to handle and which overcomes the energy barrier of the hollow fiber approach.