1. Title: Ultrashort Light Sources: From Femtosecond to Attosecond
2. Date and Time: Thursday, October 2, 2008 16:00~17:00
3. Place: E1 Seminar Room, ME Building (N7)
4. Speaker: Prof. Nam, Chang Hee (Dept. of Physics)
High harmonics emitted from gaseous atoms driven by intense femtosecond laser pulse possess unique capability of attosecond pulse generation. At CXRC we have developed high-power femtosecond laser technology, and investigated attosecond pulse generation based on high harmonic processes. The high harmonic pulse can form an attosecond pulse train with equally spaced harmonic spectrum or an isolated single attosecond pulse with broad continuum spectrum. Rigorous temporal characterization of attosecond harmonic pulses is an important step for proper understanding of the interactions between attosecond pulses and matter. By applying a cross correlation technique to the photoionization process by harmonic and IR femtosecond pulses, we have achieved the complete temporal reconstruction of high-harmonic attosecond pulse trains using the FROG method. In addition the direct CEP locking method, developed at CXRC to stabilize CEP of a femtosecond laser, will be explained; we recently realized the CEP stabilization of a femtosecond oscillator for 24 hours without realignment of any optical components.