1.2 Ultrafast Laser Physics and Nonlinear Optics
Project coordinator(s): G. Steinmeyer, M. Schnürer, T. Nagy

Project Goals

Project 1.2 deals with methods for generation and characterization of ultrashort pulses as well as with their application in nonlinear optics. To this end, we develop laser sources exhibiting parameters that are out of reach of commercial laser systems.

Our research on ultrafast nonlinear optics comprises fundamental studies on optical nonlinearities as well as nonlinear optical methods for the generation or characterization of ultrashort light pulses. Many fundamental nonlinear optical effects have already been described back in the 1960’s, however, there is still a lot of uncharted territory, e.g., when it comes to high-order effects, such as the higher-order Kerr effect, or to the response time of quasi-instantaneous optical nonlinearities. Other interesting areas of research include the appearance of extreme-value events (aka optical rogue waves) or optical filamentation. A second branch of research is dedicated to measurement methods for ultrashort laser pulses, in particular when their envelope only encompasses a few oscillations of the electric field. One highly versatile method is interferometric frequency-resolved optical gating, which has also proven its usefulness as a spectroscopic tool for nonlinearities with few-cycle response times. We are further developing methods to push the limits towards accurate measurements of single-cycle pulses and to investigate the dynamics of unstable pulse trains. These studies go hand in hand with our research on novel pulse generation and compression schemes.

A further major objective of project 1.2 is the development of advanced ultrashort pulse laser sources that operate in the near-IR and mid-IR spectral range. In support of this development, new laser geometries and pump schemes, special modes of operation, e.g., burst-mode lasers, as well as suitable pulse-shaping techniques are also investigated. Applying new adaptive optical systems with few-cycle capability, the techniques for shaping and diagnosing ultrashort pulses can be substantially expanded. This adaptability paves the way for the study of new phenomena, as they are met in ultrafast singular optics or plasmonics. A major part of the results generated in this project is directly applied for implementing new laser systems for MBI.

Furthermore, we develop novel ultrabroadband OPCPA systems, which operate in the near-IR or mid-IR and exploit some of the advanced pump sources currently under development. One motivation for this development is the fact that longer wavelengths in the mid-IR enable shorter cut-off wavelengths in high-harmonic generation and are also favorable for driving hard x-ray plasma sources. Amplified picosecond pulses from Yb-based systems are considered ideal for pumping OPCPA schemes seeded by 2-µm lasers while parametric generation of yet longer wavelengths in the mid-IR requires amplified picosecond or nanosecond pulses in the 2-µm spectral range. Additionally, new schemes and specifically designed materials for broadband parametric amplification in the mid-IR are also investigated.

Our development activities in high-energy thin-disk laser systems have resulted in continuous improvement within the last decade. Nowadays, our Yb:YAG thin-disk laser systems deliver more than 1 J pulse energy and are simultaneously used for pumping a high-power OPCPA system at 800 nm to produce few-cycle pulses (project 4.1) as well as for exciting a plasma X-ray source (project 3.3). Recently, our thin-disk laser activity was expanded to Ti:sapphire crystals as active medium, successfully exploiting this new development for a power amplifier in a high-field Ti:sapphire laser. Further activities at the high-field Ti:sapphire laser are primarily focused on further improvement of pulse parameters, in particular the temporal contrast, as well as on development of diagnostics for their characterization.


Measured IFROG trace in log scale for a ZnO nanorod sample (laser source: 750 nm, 8 fs, 4nJ). The trace has been divided into SHG and UV-PL parts at 391 nm (white dashed line), emission peaks of which reside respectively at 410 nm and 381 nm. Top and bottom traces show interferometric autocorrelations obtained via spectral integration of the two parts of the central trace reveal peak-to-background ratios of 7.3:1 for SHG and 84:1 for UV-PL. The SHG fringes tilt with increasing delay (green dash-dotted lines) while the UV-PL fringes remain parallel to the wavelength axis (green dotted lines)



Key Publications:

BBD15 S. Birkholz, C. Brée, A. Demircan, and G. Steinmeyer
Predictability of rogue events
Physical review letters 114 213901 (2015)
URL, DOI or PDF-File
HHB15 Michael Hofmann, Janne Hyyti, Simon Birkholz, Martin Bock, Susanta K. Das, Rüdiger Grunwald, Mathias Hoffmann, Tamas Nagy, Ayhan Demircan, Marco Jupé, Detlev Ristau, Uwe Morgner, Carsten Brée, Michael Woerner, Thomas Elsaesser, and Günter Steinmeyer
Noninstantaneous polarization dynamics in dielectric media
Optica 2 151-157 (2015)
URL, DOI or PDF-File
CCN16 V. Chvykov, H. Cao, R.S. Nagymihaly, M. Kalashnikov, N. Khodakovskiy, R. Glassock, L. Ehrentraut, M.Schnuerer, and K. Osvay
High peak and average power Ti:sapphire thin disk amplifier with extraction during pumping
Optics Letters 41,13, 3017-3020 (2016)
URL, DOI or PDF-File
TNA16 P. Trabs, F. Noack, A. S. Aleksandrovsky, A. I. Zaitsev, and V. Petrov
Generation of coherent radiation in the vacuum ultraviolet using randomly quasi-phase-matched strontium tetraborate
Optics Letters 41 618-621 (2016)
URL, DOI or PDF-File
GBU16 L. von Grafenstein, M. Bock, D. Ueberschaer, U. Griebner, and T. Elsaesser
Ho:YLF chirped pulse amplification at kilohertz repetition rates - 4.3 ps pulses at 2 µm with GW peak power
Optics Letters 41 (2016)in press
URL, DOI or PDF-File

Link to all project related publications