Dresden 2011 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 29: Laserentwicklung: Nichtlineare Effekte 1

Q 29.5: Vortrag

Mittwoch, 16. März 2011, 11:30–11:45, SCH 251

Saturable absorption and nonlinear refractive index in composites doped with metal nanoparticles — •Kwang-Hyon Kim, Anton Husakou, and Joachim Herrmann — Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, Max-Born-Str. 2a, 12489 Berlin

Commonly applied saturable absorbers for passive mode-locking of lasers are semiconductors, especially multi-quantum wells. However, in the short wavelength range below 700 nm attractive saturable absorbers are still missing. In the present talk we demonstrate that composites doped with metal nanoparticles can provide the required photonic element. By using a modified self-consistent Maxwell-Garnett formalism for spherical nanoparticles and a generalization of the discrete-dipole formalism for particles with arbitrary shape we show that the total absorption coefficient exhibit strong saturation behaviour near the plasmon resonance with saturation intensities in the range of 10 MW/cm². The plasmon resonance can be shifted in a wide wavelength range by choosing nanoparticles of different size and shape. This paves the way to a new class of designable saturable absorbers in the wavelength range of 400∼700 nm, where standard types of saturable absorbers are hard to apply. In addition, we study also the nonlinear refractive index and the field enhancement factor in the considered composites.