Ultrafast All-Optical-Switching using Low Permittivity Material

Mohammad Zahirul Alam Department of Physics, University of Ottawa, Ottawa, Ontario, Canada Israel De Leon Department of Physics, University of Ottawa, Ottawa, Ontario, Canada Robert Boyd Department of Physics, University of Ottawa, Ottawa, Ontario, Canada Institute of Optics, University of Rochester, Rochester, New York, USA

We excite surface plasmon between a nonlinear superstrate and a gold film. Using a pump-probe experiment we show that high signal-to-noise ratio can be achieved with a low permittivity film of sub-wavelength dimension as the nonlinear superstrate on a gold film. A pump beam changes the refractive index of the superstrate thin film through Kerr-like nonlinear mechanism. This changes the plasmon resonance condition. We also show that the response time is less than a few picoseconds. Due to the exceptionally large nonlinear index change of the superstrate film, the required power is also relatively low. We give an outline on how to reach femtojoule per bit switching energy using a more novel plasmonic structure for stronger field enhancement.

Our result is of fundamental interest not only for the engineering of all optical signal processing devices, but also for the advancement of the field enhanced plasmonic nonlinearity.

zahir@uottawa.ca