Düsseldorf 2007 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

Q: Fachverband Quantenoptik und Photonik

Q 10: Nichtlineare optische Effekte und Lichtquellen II

Q 10.4: Vortrag

Montag, 19. März 2007, 14:45–15:00, 5J

Noncollinear optical parametric amplification of vacuum fluctuations, cw light, and continua — •Christian Homann, Markus Breuer, Stefan Lochbrunner, and Eberhard Riedle — LS für BioMolekulare Optik, LMU München

We have investigated a blue pumped two-stage noncollinear optical parametric amplifier that was operated in three different modes. In all cases we obtain µJ visible output at 1 kHz repetition rate. With seeding by a supercontinuum generated in a sapphire plate, broadband pulses with fluctuations in the 1% rms range are obtained. The spectrum is nearly structureless and highly reproducible from shot to shot. A single longitudinal mode cw laser (532 nm) renders as seed extremely clean 88 fs pulses, close to the Fourier limit given by the 6 nm bandwidth and the 170 fs pump pulse. The output does, however, fluctuate by about 30% due to the less than 500 seed photons per pulse. When neither the cw seed nor the continuum is used, the second amplifier stage is seeded by the parametric super-fluorescence generated in the first stage. This is the typical OPG/OPA configuration. The single shot spectral analysis shows that the spectrum is highly structured and varies from shot to shot dramatically and needs about 500 shots averaging to converge to a stable and smooth distribution. The width of each individual spectral structure is identical to the one found in cw seeding and the height varies largely. We conclude that we amplify individual photons out of the vacuum fluctuations and each amplification process starts at a different depth in the first amplifier crystal.