Ultrafast nanooptics

Adaptive control of tip-enhanced near-field signals in carbon nanotubes (Hartschuh)

We propose to develop an ultrafast tip-enhanced near-field optical technique using single-walled carbon nanotubes as model nanostructures.

The goal of the project is controlling and maximizing optical signals from carbon nanotubes placed in metal nanostructures using polarization-shaped ultrafast pulses. The tip of a tip-enhanced near-field optical microscope (TENOM) can be used to either vary the configuration of the metal nanostructure (for a metal tip) or map the field distribution resulting from the optimization.

In the first part of the project we test the experimental apparatus and the concepts of coherent control on the nanoscale using the nonlinear response of gold: second harmonic generation and nonlinear photoluminescence.
In particular we probe the local shaping of the field caused by plasmonic resonances. In a proof of principle experiment second harmonic generation in a set of gold nanostructures with varying geometrical parameters is excited using shaped fs pulses. Pulses will be significantly shaped only by the plasmonic resonances which are tuned to the incident wavelength. Correspondingly, the optimal pulses for the non-resonating nanostructures will be in general quite similar to each other (and not too different from the shortest incident pulses), while for the resonating nanostructures, the optimal pulses will exhibit a significant spectral phase, which compensates the shaping imparted by the plasmonic resonance.

In the second part of the project we introduce more complex metal nanostructures and the carbon nanotubes. Besides a proof-of-principle demonstration of local shaping of optical pulses, this project will provide also a prototype of optical spatial switching at the nanoscale.


Controlling near-field optical intensities in metal nanoparticle systems by polarization pulse shaping
Giovanni Piredda, Caroline Gollub, Regina de Vivie-Riedle, Achim Hartschuh
Appl. Phys. B 100 (2010) 195
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