ICORP International Cooperative Research Project of the Japanese Science Fund JST and MPQ

Research Master Plan: Ultrashort Pulse Laser Project

  Recent research activities are centered in bio-, nano- and information sciences technologies in these days. Light or photon related science and technologies are highly related to all of them and have contributed a lot to the development of theses research fields. Especially studies using ultrashort pulses have recently developed explosively. Among various related fields, metrology attracted attention and the Nobel Prize was awarded to Prof.  J. Hall and Prof. T. Hänsch in 2005. They used carrier-envelope phase (CEP) stabilized mode-locked pulses for a new frequency comb. There are extensive possible applications to communication, bioscience and technology, and medical application. Short pulses have advantages of having higher peak power than longer pulses with the same pulse energy. Taking advantage of this, ultrashort pulses can be used in laser machinery without thermal effects and higher signals to noise ration in nonlinear optical imaging.

Prof. Kobayashi’s group (Japanese Group) has been the forerunner in the femtosecond visible pulse generation by using optical parametric process in a novel configuration of non-collinear parametric amplifier (NOPA). Not only generation of short pulse but also the Japanese Group was successful in the application of such short pulses to real-time vibrational spectroscopy and transition spectroscopy. Technologies developed by the Japanese Group have been utilized in the efficient generation of correlated photon states. Common process to both the ultrashort pulse generation and the entangled photons is a parametric interaction of laser through nonlinearity in materials. Not only the ultrashort light source was developed but also multi-channel highly sensitive detection system was developed. Combination of the two has enabled the real-time observation of molecular vibration, which provides the instantaneous molecular structure during relaxation, chemical reaction, and molecular vibration.

Prof. Krausz’s group (German Group) has been at the frontier of attosecond soft-X-ray pulse generation based on high-order harmonic generation of CEP-stabilized intense few-cycle laser pulses and attosecond pulse characterization by use of the attosecond-streak camera resolving 250 as in time. In this framework, German researchers are developing ultrashort laser sources for X-ray pulse generation and the detection and control of electron wavepackets as an application. The soft-X-ray and X-ray regime are covered by the research of the German Group, which is complementary to the spectral range of ultraviolet, visible, and infrared, covered by the research of the Japanese Group. The time range of attosecond laser pulses in the German Group is also complementary to the femtosecond and picosecond regime planned in the Japanese Group.

Collaborative relationships between the Japanese and German Groups started several years ago. Members of the Japanese Group who developed NOPA, which can generate the world shortest visible pulses and produce passive CEP stabilized short pulses, did research in the German Group to develop the hybrid CEP stabilization system by combining the passive method developed in the Japanese Group with the active method developed by the German Group.

Aims:
Purpose of this research is to develop ultrafast laser sources and its applications in cooperation with the German and Japanese Groups. The Japanese Group will pursue development of CEP stabilized ultraviolet, visible and infrared femtosecond laser system, and development of ultrabroadband high sensitive detection system, as well as investigating photo-chemical reaction, photo-induced phase-transition and ultrafast dynamics changes up to 1 fs temporal resolution and 0.02 Angstrom spatial resolution. The German Group will develop a driver laser for coherent attosecond soft-X-ray and X-ray pulse generation and apply to ultrafast X-ray diffraction in order to investigate the ultrafast structural dynamics and change of, for example, protein and so on.

Within this frame work of the ICORP, strong collaboration between the German and Japanese Groups is necessary for the generation of ultrashort CEP stabilized infrared laser system which can be applied to both (a) phase-sensitive molecular vibrational dynamics research by thermo-chemical and photo-chemical reactions to be held in the Japanese Group and (b) driving laser for extension of high-harmonic generation cut-off and extended streaking method to be held in the German Group.

Goals:
To extend the cut-off of high harmonic generation beyond the current soft-X-ray regime, intense IR few-cycle driving pulses will be used. The infrared laser source is advantageous for increasing of the ponderomotive potential which scales with the square of the center wavelength of the laser pulse and is responsible for the highest obtainable HHG photon energies (cut-off). Using a quasi-phase-matching scheme in HHG will help to increase the X-ray photon flux.

In this research, infrared ultrashort laser pulse development is to be done under the close collaboration between the Japanese and German Groups. The German Group will pursue the extension of the cut-off of high harmonic generation, while the Japanese Group will develop a similar infrared laser system for the control of molecules.

As a blueprint, coherent X-ray generation would lead to the revolutionary achievements in medical and technological fields within 10 years.

The goals of the Ultrashort Pulse Laser Project are summarized as follows:

(1) Control of vibronic motion on molecular frames with the aim to develop ultimate solutions to controlling reactions in complex molecular systems
(2) Real-time observation of photophysical, photochemical, and photobiologoical processes with 1fs and 0.02 Angstrom resolution by electronic and vibrational spectroscopy
(3) Control of electronic motion on molecular orbital with the aim to develop ultimate solutions to controlling reactions in complex molecular systems
(4) Tracing electronic and nuclear dynamics in complex molecular systems by attosecond X-ray photoelectron spectroscopy and diffraction

 To accomplish the above goals, the Japanese Group will mainly conduct (1) development of a proto-type source of waveform-controlled (CEP controlled)) few-cycle IR pulses, (2) development of a CEP stabilized UV-VIS and IR fs sources, (3) development of multi-channel lock-in detector with rapid scan mechanism and application of such system to ultrafast vibration real-time spectroscopy to obtain instantaneous molecular structure with 0.02 Angstrom resolution. The German Group will mainly conduct (1) development of a high-power source of waveform-controlled (CEP controlled) few-cycle IR pulses, (2) Synthesis of intense ultrabroadband (several-octave-spanning) UV-VIS-IR light waveforms, (3) extending attosecond pulse generation and metrology into the X-ray regime and optical streak camera.

All the know-how of the developments at the German Group will be transferred to the Japanese Group as well as there will be support in ordering hardware components and setting up the systems in Japan. The systems to be developed can in particular be used for IR spectroscopy in the Japanese Group. A comparison of scientific results in IR spectroscopy in the Japanese Group and X-ray photoelectron spectroscopy in the German Group will provide a high-quality scientific output.

• more information

  Top