Carrier-envelope phase dependent high-order harmonic generation with a high-repetition rate OPCPA-system

Abstract

Abstract. We study high-order harmonic generation with a high-repetition rate (200 kHz), few-cycle, driving laser, based on optical parametric chirped pulse amplification. The system delivers carrier-envelope phase stable, 8 fs, 10 μJ pulses at a central wavelength of 890 nm. High-order harmonics, generated in a high-pressure Ar gas jet, exhibit a strong CEP-dependence over a large spectral range owing to excellent stability of the driving laser pulses. This range can be divided into three spectral regions with distinct CEP influence. The observed spectral interference structures are explained by an analytical model based upon multiple pulse interferences.

Compact 200 kHz HHG source driven by a few-cycle OPCPA

“…Different laser technologies for driving HHG at high-repetition rate systems were demonstrated so far, e.g. based on intra cavity HHG [5], Yb-doped fibre amplifiers [6], thin-disk oscillators [7], few-cycle Ti:Sa lasers [8], or few-cycle optical parametric chirped pulse amplifier (OPCPA) systems [9,10]. While there is no fundamental reason for the HHG conversion efficiency to drop with decreasing laser pulse energy and tighter focusing [11], efficient HHG with a pulse repetition rate of >100kHz and driving pulse energy in the µJ range still is experimentally challenging.…”

Extreme-ultraviolet high-order harmonic generation from few-cycle annular beams

“…Another possibility to suppress the residual IR radiation for low-average laser power is filtering by thin metallic foils, which are transparent to the XUV radiation [9,10,17], or using a micro-channel plate detector [18]. With the recent development in laser sources, high power, highrepetition laser sources are now available from optical parametric chirped pulse amplification [19,20], fiber [21,22], and thin-disk lasers [23]. These systems are capable of delivering pulse energies of several 100 μJ at several 10-100 kHz repetition rate.…”

Phase and polarization changes of pulsed Gaussian beams during focusing and propagation

“…This is also the area where the importance of the exact temporal variation of the electric field in the electromagnetic pulses showed up. The influencing effect of the phase (or the CEP -this is how often it is referred to) has already showed up in high-harmonic generation [56][57][58], in the phasesensitive nature of photoemission [59][60][61], in surface-plasmon electron acceleration [62], or during the generation of photocurrents [63].…”

“…On the contrary to the fact that its importance has been recognized for two decades now [108], and that the survey to find its effects on different phenomena is heavily researched [56][57][58][59][60][61][62][63], it varies from study to study what is exactly understood as the expression "carrier-envelope phase". This ambiguity originates from terminology that spread in topics of laser oscillators and pulse trains, facing with the nomenclature of studies dealing with single short pulses.…”

“…As several nonlinear optical phenomena depend on the CEP [17,[56][57][58][59][60][61][62][63], it is important to know its changes during the focusing of the pulse. While in the laser oscillator the difference between these two velocities is caused by the dispersion of the materials inside, in the free space it is a result of the wavelength dependence of diffraction, acting as a kind of dispersion [164].…”