Hugo Pires

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.

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.

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

Generation of ultrabroadband energetic laser pulses by noncollinear optical parametric chirped pulse amplification

Optical parametric chirped pulse amplification (OPCPA) is currently one of the leading techniques for the generation of ultra-powerful laser pulses, from the multi-terawatt to the petawatt range, with extremely high peak intensities. A properly designed OPCPA setup is able to provide gain over bandwidths extending hundreds of nanometers in the visible and near-infrared, allowing the generation of high-quality, energetic, few-cycle pulses. In this paper we describe the design and performance of a compact laser amplifier that makes use of noncollinear, ultrabroadband amplification in the nonlinear crystal yttrium-calcium oxyborate (YCOB). The pump and the supercontinuum seed pulses are generated from a common diode-pumped amplifier, ensuring their optical synchronization. This laser will be used as a source of ultrashort (~20 fs), energetic (~20 mJ), tunable pulses in the near infrared.

High dynamic range measurement of the pulse contrast in a Ti:sapphire/Nd:glass multiterawatt laser

We describe the design and implementation study of a high dynamic range, third order contrast-ratio measurement diagnostic for a high power laser chain. The device, known as Optical Parametric Amplification Correlator (OPAC) is based on degenerate three-wave mixing in a nonlinear crystal, it is self-referencing and compact. By measuring the idler pulse with a slow detector and a set of calibrated filters, a dynamic range of up to 1010 is achievable. The pulse contrast is to be characterized at the mJ-level, 10 Hz, Ti:sapphire pre-amplifier stage, in a time window of 100 ps.