Numerical simulations for performance optimization of a few-cycle terawatt NOPCPA system

Abstract

We present a systematic numerical design and performance study of an ultra-broadband noncollinear optical parametric chirped pulse amplification (NOPCPA) system. Using a split-step Fourier approach, we model a three-stage amplifier system which is designed for the generation of 7 fs pulses with multi-terawatt peak intensity. The numerical results are compared with recent experimental data. Several important aspects and design parameters specific to NOPCPA are identified, and the values of these parameters required to achieve optimal working conditions are investigated. We identify and analyze wavelength-dependent gain saturation effects, which are specific to NOPCPA and have a strong influence on the parametric amplification process. Noncollinear optical parametric chirped pulse amplification (NOPCPA) has attracted a lot of attention recently because of its potential as a source of few-cycle laser pulses with peak intensities exceeding a terawatt [1]. Such highintensity ultrashort pulses have many applications in the field of strong-field physics [2], e.g., as a driver source for the generation of single attosecond pulses at extreme-ultraviolet wavelengths [3], or for relativistic optics in the few-cycle pulse regime [4]. In addition, laser-based particle accelerators using few-cycle pulses have recently become the subject of investigation [5].Therefore, it is not surprising that research on NOPCPA has been expanding rapidly in the last few years, with many demonstrations of new NOPCPA implementations at various wavelengths, repetition rates and intensities. This progress has led, for example, to the first demonstration of sub-10-fs pulses with a peak intensity exceeding one terawatt [6] and to the development of a table-top laser system delivering 45 fs pulses with 200 TW peak intensity [7]. Carrier-envelope phase-stable NOPCPA systems have already been constructed for lower peak intensities [8,9]. Recently, we have demonu E-mail: kse.eikema@few.vu.nl strated an NOPCPA system which produces near-Fourierlimited 7.6 fs pulses with a peak intensity of 2 TW running at a 30 Hz repetition rate [10]. This system also proved that NOPCPA can be used to amplify pulses with very low levels of parametric fluorescence (less than 0.2% of the total integrated energy), and a pre-pulse contrast of 10 −8 was achieved. Besides producing the shortest terawatt-intensity pulses ever achieved with the NOPCPA technique (only 2.7 optical cycles), this system approaches the theoretical limits that can be expected from such a 532 nm pumped BBO-based NOPCPA system [1,11].The theoretical basis for NOPCPA has its origin in the well-known process of optical parametric amplification and is therefore well established [1,[11][12][13]. However, the theoretical research and numerical simulations specific to NOPCPA that have been published all seem to focus almost exclusively on the achievable power and gain bandwidth by exploring different types of phase-matching geometries [14][15][16]. Although this has led to designs for ultrashort pul...

XUV frequency-comb metrology on the ground state of helium

“…Because parametric amplification influences the phase of the amplified light [61,62], a method is needed to detect a differential phase shift between the pulses. This shift is recorded for each laser shot by using spectral interferometry with the original comb pulses as a reference in a Mach-Zehnder configuration (Fig.…”

Multi-kHz, multi-mJ, phase stabilized, OPCPA amplifier system

“…2. Amplification in a BBO-based non-collinear optical parametric amplifier (NOPA) yields gain bandwidth as wide as 300 nm ranging from 700 to 1000 nm, enabling the amplification of few-cycle pulses [13]. Nevertheless, stretching and compressing pulses spanning over 300 nm of bandwidth requires compensating dispersion up to the fourth order.…”

Design considerations for a high power, ultrabroadband optical parametric chirped-pulse amplifier

“…Existing analytical solutions of the non-collinear optical parametric amplifier (NOPA) processes provide an accurate estimate of the gain bandwidth, but generally neglect dispersion and walk-off effects [18][19][20]. Numerical methods provide good estimates for the pulse energetics and closely reflect experimentally chosen parameters, such as, pulse energy, pulse duration, spectrum and phase [18,21]. Here, a 2D-model was developed with the z-axis along the signal propagation axis and one transverse direction (x-axis) formed in the plane between the signal and pump axes.…”