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Q: Fachverband Quantenoptik und Photonik

Q 72: Ultrashort Laser Pulses III

Q 72.1: Vortrag

Freitag, 4. März 2016, 15:30–15:45, a310

Line-by-line amplitude and phase modulation of a 10 GHz frequency comb for pump-probe spectroscopy — •Ali Seer, Oliver Kliebisch, Dirk Heinecke, and Thomas Dekorsy — Department of Physics and Center for Applied Photonics, University of Konstanz, D-78457, Germany

The time-resolved investigation of optically excited nanostructures with tailored pulse sequences is an important technique to study nanomechanical systems [1]. However these techniques are at present limited to 1 GHz or lower due to the lack of high repetition rate femtosecond pulse sources. Here we present a method to generate pulse trains with high repetition rates in the order of fundamental resonance frequencies of nanomechanical systems. Using a 10 GHz Ti:sapphire laser the wide spacing of the frequency comb modes [2] allows us to spatially resolve them using dispersive optics. Independent modulation of phase and amplitude of individual modes is performed using a spatial light modulator to realize line-by-line pulse shaping. Increase of repetition rate is achieved by optimization of modulator phase masks by a genetic algorithm. A tapered semiconductor amplifier is used in a double pass configuration to amplify pulses by factors up to 30 dB [3]. In this way intensity cross correlation measurements are carried out in a pump probe setup employing asynchronous optical sampling (ASOPS) with a second 10 GHz Ti:sapphire laser [4]. [1] Bruchhausen et al., PRL 106, 077401 (2011). [2] Bartels et al., Opt. Lett. 33, 1905 (2008). [3] Bolpasi et al., Rev. Sci. Instrum. 81, 113108 (2010). [4] Gebs et al., Opt. Express 18, 5974-5983 (2010) .