Measurement of amplitude and phase of ultrashort optical pulses by using nonlinear processes in optical fibres

Abstract

I confirm that I worked out this doctoral thesis independently and that I quoted all the literature used. Prohlašuji, že jsem tuto dizertační práci vypracoval samostatně a že jsem uvedl veš- kerou použitou literaturu. V Praze dne 21. 6. 2010 Abstract The thesis deals with the Frequency-Resolved Optical Gating (FROG) method of mea- suring ultrashort optical pulses. As a nonlinear process involved in the method we used cross-phase modulation in a microstructured optical fiber. The FROG device made of fi- ber pigtailed components fitted well the needs of our fiber optical laboratory. The output of the measurement differs significantly from FROG methods that use other nonlinear processes like second harmonic generation. For our FROG, the standard algorithms for reconstruction of the complex envelope from measured spectrogram failed. We therefore used a more robust genetic algorithm (GA) for the reconstruction. GA has several pa- rameters that affect its runs and we explored the influence of these parameters on the success of reconstruction of a number of test pulses and found the optimal set of these parameters. In this work, we present a general discussion of the FROG method and the standard reconstruction algorithms, the experimental setup we used, a discussion of the genetic algorithm, the technical details of our...