Coherent and pulse preserving supercontinuum generation in all-normal dispersion fibers
Speaker: Alexander Heidt, Laser Research Institute, University of Stellenbosch, South Africa
Date:9 December 2010
Time: 2pm
Venue: Mountbatten Seminar Room
Abstract:
Due to their design flexibility, photonic crystal fibers (PCF) are the medium of choice for supercontinuum (SC) generation in optical fibers. Current typical fiber designs, however, result in dynamics in which the SC is generated by the break up of the injected pulses, i.e. in general the resolution in the time domain and in the coherence of the input pulses are lost.
I will present numerical and experimental studies showing that all-normal dispersion (ANDi) fibers, which exhibit convex dispersion profiles flattened near the pump, are ideally suited to generate extremely flat and more than octave spanning SC spectra which are highly coherent over the entire bandwidth. Due to the suppression of soliton fission in the normal GVD regime, the SC spectra are mainly generated by self-phase modulation and optical wave breaking dynamics, resulting in smooth spectral profiles without significant fine structure. A single pulse is maintained in the time domain, which can be externally compressed to the few-cycle regime. Specific examples of ANDi fibers including PCF, optical nanofibers and tapered suspended core PCF will be discussed for broadband coherent SC generation in the near-infrared, visible and deep ultraviolet spectral regimes.