Joana Alves successfully defends Ph.D. thesis

My student Joana Alves successfully defended her PhD thesis entitled “Ultrafast mid-infrared unable sources” on September 19, 2023. Her work was supervised by Gonçalo Figueira, Hugo Pires (both at IPFN/IST) and Jens Biegert (ICFO, Spain).

During her Ph.D. in the scope of the APPLAuSE programme, Joana specialised in the study of ultrafast mid-infrared (3-8 µm) laser technology, in particular nonlinear amplification of ultrashort pulses through OPCPA and their compression.

She evaluated strategies for achieving few-cycle, millijoule-level pulses in this wavelength region, working with three different laser systems, at the Laboratory for Intense Lasers, IST and at the Attosecond and Ultrafast Optics group at ICFO. One of the main results is the implementation study of a new ultrafast (5-optical-cycles), high energy (5 mJ), 3 μm laser system and an analysis of the main challenges for compressing pulses at this wavelength range.

The PhD jury, consisting of Greg Greetham (STFC, UK), Olivier Chalus (Thales, France), Ana G. Silva (FCT-UNL, Portugal), Gareth Williams (IPFN/IST), Gonçalo Figueira and Luís L. Alves (both Phys. Dept. IST), unanimously highlighted the significant amount of effort, the quality and the high impact of her achievements.

Congratulations, Joana!

New paper in Optics Express

Our most recent work on spectral broadening in multipass cells was now published in Optics Express, with my former PhD student (now Dr.) Victor Hariton as the first author and main driving force behind this idea, together with collaborators K. Fritsch, K. Schwarz, N. Kovalenko, G. Arisholm and O. Pronin.

In this work, we introduce a novel multi-pass convex-concave arrangement, which exhibits crucial properties such as large mode size and compactness. In a proof-of-principle experiment, 260 fs, 15 µJ and 200 µJ pulses are broadened and subsequently compressed to approximately 50 fs with 90% efficiency and excellent spatio-spectral homogeneity across the beam profile. We simulate the proposed concept for spectral broadening of 40 mJ and 1.3 ps input pulses and discuss the possibility of further scaling.

To know more:

Victor Hariton, Kilian Fritsch, Kevin Schwarz, Nazar Kovalenko, Gonçalo Figueira, Gunnar Arisholm, and Oleg Pronin, “Spectral broadening in convex-concave multipass cells,” Opt. Express 31, 19554-19568 (2023)

Farewell to Victor

My student Victor Hariton has left the team and moved to star a postdoc position at the Laser Science and Technology team of DESY, in Germany,

During his stay in our team, Victor gave contributions in different fields, from femtosecond ablation with shaped pulses (for which he was awarded the Gulbenkian Stimulus to Scientific Research prize in 2017) to studies in thermal lensing in Yb-doped media, amplifier development and more recently to nonlinear spectral broadening and pulse compression in multipass cells, in collaboration with Oleg Pronin‘s team at HSU.

Best wishes to Victor!

Invited talk at USTS2022

This Friday I will be delivering an invited talk at the 2022 Ultrafast Science & Technology Spain conference, which takes place from Nov. 16th to 18th, Málaga.

I will talk about the status and perspectives of ultrafast laser research and applications in Portugal, highlighting the work of teams at IST, Coimbra and Porto.

Paper accepted in Optics Letters

Victor Hariton has just published another paper covering an important part of his PhD research, resulting from the successful collaboration with Oleg Pronin‘s team at HSU.

In this work, multipass spectral broadening and compression around 515 nm are experimentally demonstrated. A nonlinear multipass cell with a bulk medium is used to compress 250-fs pulses down to 38 fs. The same input pulses create a sufficient bandwidth for sub-20-fs pulse generation in a multipass cell with gaseous media. In both cases, the efficiency exceeds 85%. Dispersion management by reduction of the cell size and the thickness of the nonlinear medium allows an efficient generation of ultrashort pulses in the visible range and establishes a pathway for ultraviolet spectral broadening by means of multipass cells.

V. Hariton, A. Bin Wahid, G. Figueira, K. Fritsch, and O. Pronin, Multipass spectral broadening and compression in the green spectral range. Optics Letters 47, 1246-1249 (2022)