Gonçalo Figueira

Self-referencing spectral phase interferometry for direct electric-field reconstruction with chirped pulses

We analyze the characterization of strongly chirped pulses by spectral phase interferometry for direct electric-field reconstruction (SPIDER). We show how to extend the working range of this technique for these relevant cases and derive correction factors for typical operating parameters. The results are straightforward to implement in the calculation algorithms. We demonstrate the validity of this technique by characterizing numerically and experimentally pulses with a known spectral phase profile.

Bandwidth increase by controlled angular dispersion of signal beam in optical parametric amplification

Angular dispersion of the signal beam inside the nonlinear media is introduced to improve the non-collinear phase-matching range. Simulations run for BBO crystals predict that bandwidth increase is possible for most of the application spectral range and that it can surpass one order of magnitude in some particular configurations.

Single adjuster deformable mirror with four contact points for simultaneous correction of astigmatism and defocus.

We show that a deformable mirror with four point actuators is suitable for the simultaneous correction of astigmatism and defocus in a given optical system by adequately choosing the relative position of the actuators. An analytical model is developed that describes adequately the mirror deformation as a function of actuator position, showing that it is possible to continuously tune the weight of each aberration. Experimental measurements with a single adjuster deformable mirror assembly confirm the validity of the model.

Mirrorless single-shot tilted-pulse-front autocorrelator

Ultrashort pulses exhibiting angular dispersion have their pulse front tilted relative to the phase front. This leads to a serious degradation in the focused peak power, making the use of adequate diagnostics indispensable. Here we present an upgrade to a previously demonstrated uniaxial single-shot autocorrelator for ultrashort laser pulse-width measurements that extends its versatility, by making it suitable for detecting and correcting tilted pulse fronts. We have used this diagnostic to optimize the alignment of our chirped-pulse-amplification grating compressor.

Increased bandwidth optical parametric amplification of supercontinuum pulses with angular dispersion

The use of a controlled, removable angular dispersion applied to the signal beam in a plane orthogonal to that containing the noncollinear angle is experimentally demonstrated as a technique to broaden the gain bandwidth in optical parametric chirped-pulse amplification. With a pump beam centered at 526 nm the supercontinuum signal is amplified in the 900 to 1220 nm range in a beta-barium borate crystal with a gain >1000. This represents a bandwidth improvement greater than 30% relative to conventional designs.

Performance and characterization of a 2.8-TW Ti:sapphire-Nd:glass chirped pulse amplification laser system

The Laboratory for Intense Lasers (L2I) facility is equipped with a multi-Terawatt Ti:sapphire-Nd:glass chirped pulse amplification laser system delivering 2.8 TW pulses at 1053 nm. Here we present the laser configuration and characterize its current performance, and describe the diagnostics and methods used for this characterization.

Dispersion compensation by two-stage stretching in a sub-400 fs, 1.2 mJ Yb:CaF 2 amplifier

We generate 1.24 mJ, 390 fs pulses at 1035 nm in a CPA laser system featuring a 2.8 mJ Yb:CaF(2) regenerative amplifier, stretcher/compressor based on a single chirped volume Bragg grating and a compact, low-dispersion grating compressor. The auxiliary compressor is used to effectively pre-compensate the intra-cavity dispersion of the amplifier.

Numerical evaluation of ultrabroadband parametric amplification in YCOB

The technique of optical parametric chirped pulse amplification has the potential to generate high-energy few-cycle pulses at high repetition rates, thanks to its high fidelity and ultrabroadband capability. The biaxial nonlinear crystal yttrium calcium oxyborate (YCOB) exhibits a favorable set of optical and thermal properties for these purposes. We evaluate numerically the performance of this crystal as the nonlinear medium in a parametric amplifier for a wide range of phase-matching parameters. We explore optimized ultrabroadband noncollinear optical parametric amplification by operating at phase-matching angles outside the principal planes.

Hybrid diode-pumped Yb:CaF2/YAG laser system delivers 20 mJ pulses at 1050 nm for Nd:glass amplifier seeding

We report a 20 mJ diode-pumped pulsed laser system operating at 1050 nm, featuring a hybrid CPA laser system composed by a 2.5 mJ Yb:CaF2 regenerative amplifier and a 20 mJ, eight passes Yb:YAG amplifier.

Numerical simulations for OPCPA crystals: YCOB performance and use in different regimes

In this work we perform a simulation study for yttrium calcium oxyborate (YCOB) as the nonlinear medium for optical parametric amplification. These results will be used to design a new large bandwidth, 10 Hz, OPCPA stage at the Laboratory for Intense Lasers at IST, pumped by an ytterbium-based amplifier and seeded by a white light continuum. Different regimes are tested to assess the scalability of the material