Stuttgart 2012 – scientific programme

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MO: Fachverband Molekülphysik

MO 1: Vibrational Spectroscopy

MO 1.3: Talk

Monday, March 12, 2012, 11:15–11:30, V38.03

Multimodal non-linear imaging with shaped femtosecond pulses — •Jean Rehbinder, Tiago Buckup, and Marcus Motzkus — Physikalisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, D-69120 Heidelberg, Germany

Multimodal non-linear imaging takes advantage of the simultaneous generation of different optical signals, like second and third harmonic generation (SHG and THG), two-photon excited fluorescence (2PEF) and four-wave mixing (FWM). SHG and THG highlight structured molecules and interfaces, whereas 2PEF is generated by specific fluorophores. FWM, on the other hand, provides contrast based on the specific third-order nonlinear susceptibility. A promising way to improve multimodal non-linear imaging is phase and amplitude shaping of the excitation pulses. Contrast and selectivity can be improved by addressing specific fluorophores emitting in the same spectral region or even by retrieving the Raman information. This work in based on the phase and amplitude shaping of a single beam from a broadband Ti:Sapphire oscillator applied to microspectroscopy. A first benchmark is presented by comparing the effect of standard Taylor-phase distortions on the different non-linear signals. The separation of spectrally overlapping 2PEF and FWM signal is studied in a plant cell. We also discuss the effect of optimization of SHG or FWM using imaging of a tendon from a rat-tail.