Ultrashort optical pulse characterization
Date
2008-03
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Stellenbosch : University of Stellenbosch
Abstract
Various autocorrelation techniques are employed to characterize ultrashort
laser pulses in both the temporal and spectral domain. These techniques
are; interference autocorrelation (IAC), modified spectrum autointerferometric
correlation (MOSAIC), background-free autocorrelation (BFA) and frequency
resolved optical gating (FROG). All of these techniques are based
on the interaction of a pulse with a time delayed copy of itself within a Â(2)
medium.
Experimental setups for BFA and FROG experiments are developed, which
exploit the phenomenon of second harmonic generation (SHG). An existing
IAC setup is used for temporal pulse characterization. MOSAIC results are
obtained through applying a specific Fourier filter to the IAC data.
IAC and MOSAIC measurements performed on a commercially available femtosecond
laser, indicate that the emitted pulse has a pulse duration less than
150 fs and possesses positive linear chirp. BFA and FROG measurements
carried out on the same laser system mirror these results.
Pulses emitted by a 20 Hz chirped pulse amplifier are characterized through
BFA and FROG. BFA results suggest that the pulse from the amplifier is
actually a double pulse. FROG results indicate that the pulse is highly
chirped.
The experiments and physical interpretations presented in this work demonstrate
the preferred methods of optical pulse characterization for ultrashort
laser pulses.
Description
Thesis (MSc (Physics))--University of Stellenbosch, 2008.
Keywords
Femtosecond, Dissertations -- Physics, Theses -- Physics, Laser pulses, Ultrashort