BEGIN:VCALENDAR VERSION:2.0 PRODID:Icfo X-PUBLISHED-TTL:P1W BEGIN:VEVENT UID:69d8d1fda27b0 DTSTART:20220503T080000Z SEQUENCE:0 TRANSP:OPAQUE LOCATION:ICFO Auditorium SUMMARY:ICFO | UGAITZ ELU ETXANO CLASS:PUBLIC DESCRIPTION:In the last decades\, intense carrier-envelope-phase-stable (CE P-stable) and near-single-cycle\, coherent mid-infrared sources have becom e charming for a variety of applications in physics\, chemistry and biolog y. In particular\, those mid-infrared sources are of tremendous interest f or broadband spectroscopic applications\, solid-state light-matter studies \, strong-field physics research\, and attosecond science. On the one hand \, broadband coherent mid-infrared sources are capable of replacing time-c onsuming scanning techniques to classify organic structures or detect haza rdous chemical compounds. On the other hand\, high-energy\, CEP-stable\, n ear single-cycle mid-infrared sources are key in strong-field physics and attoscience due to the wavelength scaling nature of strong-field electron re-collision-based processes.\nNevertheless\, implementing such mid-infrar ed sources remains challenging due to the lack of user-friendly temporal\, spectral and spatial characterisation instruments\, efficient and afforda ble reflection/transmission coatings\, and commercially accessible low-los s dispersion compensation optics. Moreover\, the absence of suitable laser gain materials reinforces nonlinear down conversion and amplification met hods. One approach to overcoming the current limitations and developing in tense ultrafast mid-infrared systems is to use a commercially available hi gh-power near-infrared laser combined with second-order nonlinear processe s such as the optical parametric amplification (OPA) process or the optica l parametric chirped-pulse amplification (OPCPA) process. OPCPA can be ess ential to avoid damage to the nonlinear crystals or tailor the amplified s pectrum. OPCPAs are also used when femtosecond pulses are required to be a mplified using picosecond pump lasers. As a result\, OPCPA systems offer n ovel opportunities for producing high-intensity\, broadband mid-infrared f emtosecond pulses.\nHere the 160 kHz high-power mid-infrared OPCPA system is developed to overcome the existing limitations in the high-repetition-r ate mid-infrared regime. This thesis demonstrates the generation of unique 3.2 &mu\;m pulses with a single-cycle duration and delivering up to 3.9 G W of peak power. The combination of the CEP stability with the single-cycl e duration and the high energies demonstrated makes this system suitable t o produce ultrafast radiation in the kilo-electron-volt X-ray regime.\nA n ewly developed mid-infrared nonlinear crystal named BGGSe is proposed for efficient broadband infrared radiation generation. The ultra-broadband sou rce is produced using the BGGSe crystal combined with a unique anti-resona nt-reflection photonic crystal fibre (ARR-PCF) that enables tailoring the compression of our 3.2 &mu\;m pulses at 160 kHz. Using the BGGSe crystal a nd the ARR-PCF\, we demonstrate the generation of coherent light expanding up to seven octaves\, from UV to the THz regime.\nThe second mid-infrared system presented in this thesis is the high-energy 7 &mu\;m OPCPA operate d at a 100 Hz repetition rate and developed to generate hard X-rays in the multi-kilo-electron-volt regime. The development of this second OPCPA cen tred at 7 &mu\;m overcomes the considerable challenges in the mid-infrared regime. This thesis demonstrates the amplification of those mid-infrared pulses to 750 &mu\;J and the efficient back-compression to 188 fs.\nMoreov er\, high harmonic generation in solids driven by 7 &mu\;m pulses at 100 H z and 3.2 &mu\;m pulses at 160 kHz has been exploited for solid-state stud ies using the developed OPCPA systems. This thesis highlights the results achieved in the high-temperature YBCO superconductor\, where exponential e nhancement of harmonics is demonstrated below the critical temperature.\nA ll these demonstrations make those systems a key-enabling technology for t he next generation of studies in solid-state physics\, extreme nonlinear p hotonics\, strong-field physics and coherent X-ray science.\n \;\nThes is Director: Prof Dr. Jens Biegert DTSTAMP:20260410T103333Z END:VEVENT END:VCALENDAR