Special ultrafast science seminar: "Advancing Ultrashort Laser Pulse Technology: Controlling Ultrafast Electron Motion"

Monday, December 8, 2014 1:30 PM to 2:30 PM
Physical Sciences Building, Room 160

Yunpei Deng
Fritz-Haber-Institut der Max-Planck-Gesellschaft

State-of-the-art laser technology is on the verge of providing synthesized waveforms at optical frequencies. Such flexibility in shaping arbitrary light waveforms permits sculpting an electric force for steering electrons in any desired fashion within atomic, molecular and solid systems, on the electronic time scale. This has promising potential in pushing the frontiers of attosecond physics and of extending coherent control schemes to completely unexplored regions.

Optical parametric chirped-pulse amplifier (OPCPA) systems can produce nearly single-cycle pulses at the mJ energy level, or few-cycle pulses at hundreds of mJ. In my talk I will present the details of a mid-IR OPCPA laser system that I developed at Max-Planck-Institut für Quantenoptik(Munich, Germany), and briefly present a high repetition rate NIR OPCPA laser system in Fritz-Haber-Institut der Max-Planck-Gesellschaft (Berlin, Germany). As I will show, this IR system has already demonstrated an output of 1.2-mJ, 1.5-cycle (10.3fs) pulses at 2.1 µm central wavelength and at 3 kHz repetition rate. Such a source is the key to achieving HHG X-ray photons in the keV domain, and is also important to a wide range of highly interesting applications, such as the investigation of ultrafast structural dynamics and conformational changes of relevant molecules in biology. An additional benefit of the IR carrier wavelength is the increased duration of its optical cycle (e.g. 7 fs for 2.1 µm) compared with a NIR pulse (e.g. 2.5 fs for 750 nm). The increased spacing between successive half-cycles of the laser pulse provides a sufficient time window to capture the full dynamics of an arbitrary sub-femtosecond relaxation process, before the identical process is re-triggered by the next half-cycle of the laser pulse. It is a powerful and unique source for coherent control, ionization and dissociation experiments. I will additionally show how an OPCPA system, which can be developed to deliver more than two-octave bandwidth pulses, is capable of producing  sinusoidal-like, square, sawtooth or any arbitrary waveforms. Such laser pulses will open the door to many ultrafast coherent control applications.

Resume
Yunpei Deng was born in Hubei Province, China in 1978. He obtained a Ph.D Degree from the State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences in 2005. After this, he worked for one year as a postdoc in the Laser Chemistry Division in the group of Prof. Dr. Kompa at MPQ. Then he was first a postdoc, and subsequently promoted to project leader, at the Light Wave Synthesizer (LWS1) in the Max Planck Institute of Quantum Optics (MPQ), where he worked for six years, in the group of Prof. Ferenc Krausz. Now he is working at the Fritz-Haber-Institut der Max-Planck-Gesellschaft since September 2012, in the group of Dr. Ralph Ernstorfer.

Contact: Zenghu Chang (Zenghu.Chang@ucf.edu)