Project Outline

Overall objectives, approach, methodology and research training

Optical laser-based technologies are a modern key technology, aiming at scientific advancements as well as a multitude of commercial applications. Already in the last decade, European institutions considered the 21st century as the “century of the photon”. Laser-based photonic technologies are upon the most dynamic industry sectors on a global scale, with an impressive growth rate of 21 % per year (according to the SMART study, prepared for the EU commission in 2011).

Extending the range of laser applications requires a constant expansion of the accessible regimes of laser operation, e.g. with regard to available intensities, temporal resolution or accessible wavelengths. Concepts from nonlinear optics (e.g. frequency conversion, synthesis of ultra-short light pulses, or applications of multi-photon processes) provide the means to achieve this goal. Nonlinear optics is at the heart of any modern laser-based research. This holds in particular true for nonlinear optics, driven with ultra-fast lasers. The latter provide high peak intensities, hence enabling high-order nonlinearities. As prominent examples we note the generation of extreme-ultraviolet (XUV) radiation or sub-femtosecond (attosecond) light pulses. XUV radiation is required for high-resolution laser lithography in microchip production. Attosecond pulses are the fastest available device on earth to monitor even super-fast processes in real time, e.g. taking snapshots of molecules during chemical reactions or motion of charges in electronic microchips.

With regard to commercial applications of high-intensity nonlinear optics, we note the large fields of nonlinear microscopy, imaging and spectroscopy. Such techniques find a tremendous multi-disciplinary wealth of applications, e.g. in medicine, bio-technology, or engineering. Today every medical laboratory, and every pharmaceutical company use commercial nonlinear optical multi-photon microscopes. Every automobile or aerospace company applies nonlinear laser spectroscopy, e.g. to monitor and optimize combustion processes in engines.

However, nonlinear optical processes typically suffer from efficiencies well below unity. This holds in particular true, when high-order processes are involved (e.g. high-harmonic generation) or when the driving laser intensities must be limited below damage thresholds (e.g. in nonlinear microscopy of living cells). In these cases the conversion efficiencies rarely exceed 10-6...10-4. Therefore we require methods to enhance nonlinear optical processes and properties. The field of “coherent control” provides techniques to manipulate laser-matter interactions. The basic idea is to use appropriately designed light-matter interactions to steer quantum systems towards a desired outcome. Examples of possible control parameters are, e.g. the modulation of the temporal laser intensity and frequency profiles, pulse delays in sequences of laser pulses, or central carrier frequencies.

HICONO connects concepts of coherent control with high-intensity nonlinear-optical interactions. Particular scientific aims are to enhance the efficiency of nonlinear optical processes, extend the range of high-intensity laser applications, and develop novel devices based on ultra-fast high-intensity lasers. In terms of training, HICONO aims at the development of young researchers with appropriate skills to exploit the concepts of high intensity laser technologies and laser-based control, pushing it towards applications. This provides the dynamic research community with training capacities on a broad scientific and technological basis and contributes to a broad European knowledge base for laser technologies.

HICONO combines fundamental scientific investigations and technological applications of high-intensity laser-matter interactions. HICONO applies a broad methodology at a pronounced multi-disciplinary character. The projects connect physics, physical chemistry, and optical engineering, aiming at applications in laser physics (e.g. towards novel devices to measure and control ultra-fast laser pulses), physical chemistry (e.g. towards ultra-fast observation of chemical reactions), biology, medicine and engineering (e.g. towards novel devices for nonlinear optical microscopy and imaging). Academic and industry teams will closely cooperate in HICONO, to overcome technological challenges and exploit research results towards new devices.

Summaries of Work packages:

Work package 1: Coherent control of high-intensity frequency conversion
Objectives: The aim of the project is to develop and experimentally implement strong coherent-adiabatic interactions (e.g. quantum interferences, coherent superpositions of quantum states, or adiabatic passage processes), driven by ultra-fast high-intensity laser pulses in dense, atomic media. The particular aim is to apply coherent-adiabatic interactions to substantially enhance conversion efficiencies towards ultra-fast, extreme-ultraviolet (XUV) radiation pulses.

Work package 2: High-intensity nonlinear spectroscopy and microscopy
Objectives: The project deals with novel applications of ultra-fast laser pulses for high-resolution imaging. This enables imaging even of otherwise fully transparent samples, which are not accessible by conventional (linear) microscopy. We focus in particular on novel variants of nonlinear harmonic microscopy by tuning the lasers to molecular resonances in the mid-infrared regime.

Work package 3: Ultra-short pulse measurement and characterization
Objectives:  The goal of the project is to identify, study and compare various pulse characterization techniques (frequency-resolved optical gating, upconversion, chirp-scan, self referenced spectral interferometry, also involving cross-polarized wavelength generation...) compatible with ultra-fast, few-cycle optical pulses in the mid-infrared spectral regime. Particular aim is to identify the most appropriate techniques for mid-infrared pulse characterization, and exploit the findings in a demonstration device with commercial potential.

General objectives : HICONO aims at novel methods for coherent control, applied to support high-intensity ultra-fast nonlinear optics. This will establish novel and efficient types of light sources, e.g. to generate extreme-ultraviolet radiation, ultra-broad spectra or intense attosecond laser pulses. With regard to applications, HICONO will introduce novel concepts for ultra-fast spectroscopy and microscopy, as well as stimulate novel developments in laser technology, e.g. to provide novel ultra-fast light sources or new devices to characterize ultra-fast light pulses. Thus, the network is expected to yield significant contributions to high-intensity laser-matter interactions and ultra-short laser pulses, which are highly relevant for a large number of applications.

Figure 1: Schematic overview of research subjects in HICONO and definition of work packages (WPs).

General methodology : HICONO combines coherent control, nonlinear optics and high intensity laser-matter interactions. The research programme naturally involves strong contributions from laser physics and laser technology. The above figure schematically depicts the interaction between the contributing research subjects. HICONO is based on close cooperation between participants from academic and industry environment. All tasks will be conducted as joint experimental work, supported by theoretical analysis and simulations. The connections of the research programme to industry are obvious from the significant contributions of applied laser and nonlinear optical technologies. This enables us to proceed also towards commercially relevant developments. We define scientific work packages : WP1 deals with novel coherent control schemes to enhance high-intensity frequency conversion processes. WP2 aims at novel applications of high-intensity nonlinear optical processes in spectroscopy, microscopy and imaging. WP3 deals with developments of novel technologies to measure and characterize complex, ultra-short laser pulses (WP3).

Summaries of individual research projects:

X. Laforgue: Coherent-adiabatically-enhanced frequency conversion by ultra-fast lasers

Objectives: The aim of the project is to develop and experimentally implement strong coherent-adiabatic interactions (e.g. quantum interferences, coherent superpositions of quantum states, or adiabatic passage processes), driven by ultra-fast high-intensity laser pulses in dense, atomic media. The particular aim is to apply coherent-adiabatic interactions to substantially enhance conversion efficiencies towards ultra-fast, extreme-ultraviolet (XUV) radiation pulses.

K. Zlatanov: Nonlinear harmonic microscopy, driven by mid-infrared ultra-fast lasers

Objectives: The project deals with novel applications of ultra-fast laser pulses for high-resolution imaging. This enables imaging even of otherwise fully transparent samples, which are not accessible by conventional (linear) microscopy. We focus in particular on novel variants of nonlinear harmonic microscopy by tuning the lasers to molecular resonances in the mid-infrared regime.

S. Jarosch: Extension of multi-colour strong field control in atoms, molecules & clusters

Objectives: The project deals with development of coherent control strategies to steer high harmonic radiation (e.g. duration, temporal structure, efficiency, photon energy). In particular, we seek the coherent enhancement of harmonic generation to provide bright XUV attosecond sources. We will use atomic ions (where resonant enhancements are expected in the XUV), molecular systems where harmonic generation can also be controlled via alignment, and clusters where large efficiencies are anticipated due to the large nonlinear polarizability.

A. Sanchez: Kinematically complete mapping of ionization by ultra-fast laser pulses

Objectives: The project deals with attosecond electron dynamics during ionization, acceleration and recollision. We will apply a unique combination of mid-infrared, few-cycle sources and our three-dimensional reaction microscope to visualize the processes at unprecedented energy resolution and in the strong field limit, e.g. to extract information on molecular structures.

S. Bruschetta: Generation of XUV pulses from structured targets or relativistic plasmas

Objectives: This project targets the production of intense bursts of XUV radiation. Such intense pulses can be achieved by using high energy ultra-fast lasers with power of many 100 TW to drive harmonic generation towards the XUV, and by developing structured targets suitable for achieving quasi-phase matching. These techniques can ultimately be extended to single attosecond pulses. The project will provide intense sources suitable for XUV pump/XUV probe experiments.

F. Wiegandt: Multiple-pulse techniques for reconstructing complex optical wave fields

Objectives: The project aims at designing new reconstruction techniques of complex electric fields based on multiple-shearing of multiple pulses. Building upon recent results for temporal characterisation, we will extend these novel methods to the spatial domain, and for complete spatio-temporal reconstruction. We will investigate both infrared ultrashort pulses and high harmonics.

S. Sharma: High-precision, interferometric multi-wavelength distance sensor

Objectives: The goal of the project is to develop and implement new concepts to significantly improve the speed and accuracy of high-precision, interferometric distance measurement devices, and investigate the potential for ultra-fast nonlinear microscopy.

V. di Pietro: Pulse characterization techniques for ultra-short pulses in the mid-infrared

Objectives: The goal of the project is to identify, study and compare various pulse characterization techniques (frequency-resolved optical gating, upconversion, chirp-scan, self referenced spectral interferometry, also involving cross-polarized wavelength generation...) compatible with ultra-fast, few-cycle optical pulses in the mid-infrared spectral regime. Particular aim is to identify the most appropriate techniques for mid-infrared pulse characterization, and exploit the findings in a demonstration device with commercial potential.

T. Singh: Resolving electronic wave functions via high harmonic generation

Objectives: The project deals with novel applications of ultra-fast laser pulses for high-resolution imaging. This enables imaging even of otherwise fully transparent samples, which are not accessible by conventional (linear) microscopy. We focus in particular on novel variants of nonlinear harmonic microscopy by tuning the lasers to molecular resonances in the mid-infrared regime.

Contact

Prof. Dr. Thomas Halfmann

Nichtlineare Optik/Quantenoptik
Institut für Angewandte Physik
Fachbereich 05 - Physik
Technische Universität Darmstadt
Hochschulstr. 6
D-64289 Darmstadt

+49 6151 16-20740

+49 6151 16-20741 (Sekretariat)

+49 6151 16-20327

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