“Femtosecond pulse propagation through nanophotonic structures”

1. a) University of Twente, Faculty of Electrical Engineering, Mathematics and Computer Science, Integrated Optical Micro Systems, P.O.Box 217, 7500 AE Enschede, The Netherlands. Phone: +31-53-489 4440; E-mail: R.Dekker@utwente.nl. b) RWTH Aachen, Institut für Halbleitertechnik, Sommerfeldstrasse 24, 52074 Aachen, Germany. c) IREE, Department of Guided Wave Photonics, Chaberska 57, 182 51 Prague, Czech Republic . “Femtosecond pulse propagation through nanophotonic structures” R.Dekkera), E.J.Kleina), J.Niehusmannb), M.Förstb), F.Ondracekc), J.Ctyrokyc), and A.Driessena). When pulses are shorter than the roundtrip time of a resonator… When pulse lengths (200fs) are much shorter than the roundtrip time of a microring resonator filter (4ps), interference effects in the spectral response as shown with CW signals (blue) are not that obvious. However, the resulting 200fs pulsetrains at the trough port (red) and drop port (green) show resonance spectra when recorded with a spectrometer. Roundtip time Continuous wave 200fs pulse time Spectral broadening and Raman scattering. Laserpulses (200fs) with a center wavelength of 1550nm were coupled into 400x400nm straight waveguides while the output spectra were recorded at various input powers. Spectral broadening due to Self Phase Modulation (SPM) at increasing powers, caused by the Kerr nonlinearity, has been observed as can be seen in the 3D-plot below. Furthermore, the Raman effect has been identified around 1650nm. The Raman signal is growing at the expense of the 1550nm pump signal, indicating that Raman gain is taking place in the silicon waveguides. Solving the NLSE using the Split Step Fourier method. In order to compare simulation results with experiments,a simulation tool has been developed to solve the nonlinear Schrödinger equation (NLSE) using the Split Step Fourier Method (SSFM). A lot of effort has been put in the use of ‘real world parameters’ as opposed to standard methods that use normalized time- and frequency scales. Various effects like dispersion (i), linear absorption (0), two-photon absorption (2), Kerr nonlinearities (), intrapulse Raman scattering (TR) and self-steepening (/0) are taken into account.