Performance of MgO:PPLN, KTA, and KNbO3 for mid-wave infrared broadband parametric amplification at high average power

The performance of KNbO3, MgO:PPLN and KTA were experimentally compared for broadband mid-wave infrared parametric amplification at high repetition rate. The seed pulses with an energy of 6.5 μJ were amplified using 410 μJ of pump at 1064 nm to a maximum pulse energy of 28.9 μJ at 3 μm wavelength and at 160 kHz repetition rate in MgO:PPLN while supporting a transform limited duration of 73 fs. The high average powers of the interacting beams used in this study, revealed average power induced processes which limit the scaling of optical parametric amplification: in MgO:PPLN the pump peak intensity was limited to 3.8 GW/cm2 due to non-permanent beam reshaping while in KNbO3 an absorptioninduced temperature gradient in the crystal led to permanent internal distortions in the crystal structure when operated above a pump peak intensity of 14.4 GW/cm2Peer ReviewedPostprint (author's final draft

Comparing axiomatizations of free pseudospaces

Independently and pursuing different aims, Hrushovski and Srour (On stable non-equational theories. Unpublished manuscript, 1989) and Baudisch and Pillay (J Symb Log 65(1):443–460, 2000) have introduced two free pseudospaces that generalize the well know concept of Lachlan’s free pseudoplane. In this paper we investigate the relationship between these free pseudospaces, proving in particular, that the pseudospace of Baudisch and Pillay is a reduct of the pseudospace of Hrushovski and Srour

Ultrashort pulse generation in the mid-IR

Recent developments in laser sources operating in the mid-IR (3–8μm) have been motivated by the numerous possibilities for both fundamental and applied research. One example is the ability to unambiguously detect pollutants and carcinogens due to the much larger oscillator strengths of their absorption features in the mid-IR spectral region compared with the visible. Broadband sources are of particular interest for spectroscopic applications since they remove the need for arduous scanning or several lasers and allow simultaneous use of multiple absorption features thus increasing the confidence level of detection. In addition, sources capable of producing ultrashort and intense mid-IR radiation are gaining relevance in attoscience and strong-field physics due to wavelength scaling of re-collision based processes. In this paper we review the state-of-the-art in sources of coherent, pulsed mid-IR radiation. First we discuss semi-conductor based sources which are compact and turnkey, but typically do not yield short pulse duration. Mid-IR laser gain material based approaches will be discussed, either for direct broadband mid-IR lasers or as narrowband pump lasers for parametric amplification in nonlinear crystals. The main part will focus on mid-IR generation and amplification based on parametric frequency conversion, enabling highest mid-IR peak power pulses. Lastly we close with an overview of nonlinear post-compression techniques, for decreasing pulse duration to the sub-2-optical-cycle regime.Peer ReviewedPostprint (author's final draft

High power multi-color OPCPA source with simultaneous femtosecond deep-UV to mid-IR outputs

Many experimental investigations demand synchronized pulses at various wavelengths, ideally with very short pulse duration and high repetition rate. Here we describe a femtosecond multi-color optical parametric chirped pulse amplifier (OPCPA) with simultaneous outputs from the deep-UV to the mid-IR with optical synchronization. The high repetition rate of 160 kHz is well suited to compensate for low interaction probability or low cross section in strong-field interactions. Our source features high peak powers in the tens to hundreds of MW regime with pulse durations below 110 fs, which is ideal for pump-probe experiments of nonlinear and strong-field physics. We demonstrate its utility by strong-field ionization experiments of xenon in the near- to mid-IR.Peer ReviewedPostprint (published version

Talaria: Continuous Drag & Drop on a Wall Display

International audienceWe present an interaction technique combining tactile actions and Midair pointing to access out-of-reach content on large displays without the need to walk across the display. Users can start through a Touch gesture on the display surface and finish Midair by pointing to push content away or inversely to retrieve a content. The technique takes advantage of wellknown semantics of pointing in human-to-human interaction.These, coupled with the semantics of proximal relations and deictic proxemics make the proposed technique very powerful as it leverages on well-understood human-human interaction modalities. Experimental results show this technique to outperform direct tactile interaction on dragging tasks. From our experience we derive four guidelines for interaction with large-scale displays

Broadband mid-IR frequency comb with CSP and AGS from a Er,Tm:Ho fiber laser

We report on the generation of a 2500 nm bandwidth frequency comb at 6.5 μm central wavelength based on critically phase-matched parametric down-conversion in the nonlinear crystal CdSiP 2 CdSiP2 (CSP), driven by a compact Er,Tm:Ho fiber laser. The generated ultra-broadband pulses show a transform-limited duration of 2.3 optical cycles and carry up to 150 pJ of energy at a 100 MHz pulse repetition rate. For comparison, the spectrum generated in AgGaS 2 AgGaS2 (AGS) spans from 6.2 to 7.4 μm at full-width at half-maximum (FWHM) with a pulse energy of 3 pJ. A full 3D nonlinear wave propagation code is used for optimization of the noncollinear angle, propagation direction, and crystal thickness.Peer ReviewedPostprint (author's final draft

Coevolution of relative brain size and life expectancy in parrots

Previous studies have demonstrated a correlation between longevity and brain size in a variety of taxa. Little research has been devoted to understanding this link in parrots; yet parrots are well-known for both their exceptionally long lives and cognitive complexity. We employed a large-scale comparative analysis that investigated the influence of brain size and life-history variables on longevity in parrots. Specifically, we addressed two hypotheses for evolutionary drivers of longevity: the cognitive buffer hypothesis, which proposes that increased cognitive abilities enable longer lifespans, and the expensive brain hypothesis, which holds that increases in lifespan are caused by prolonged developmental time of, and increased parental investment in, large-brained offspring. We estimated life expectancy from detailed zoo records for 133 818 individuals across 244 parrot species. Using a principled Bayesian approach that addresses data uncertainty and imputation of missing values, we found a consistent correlation between relative brain size and life expectancy in parrots. This correlation was best explained by a direct effect of relative brain size. Notably, we found no effects of developmental time, clutch size or age at first reproduction. Our results suggest that selection for enhanced cognitive abilities in parrots has in turn promoted longer lifespans