Ultrafast active plasmonics at telecom wavelengths

We demonstrate a number of techniques that can be used to modulate the coupling of light to surface plasmon polaritons on gold surfaces and on a subpicosecond time scale. In one technique interfering, 150 fs, 800 nm light pulses can be used to generate a transient thermal grating on a flat gold surface and this grating can be used to couple incident light to a surface plasmon polariton. In the case of a gold-coated silicon grating, optically induced Drude contributions to the dielectric constant of the silicon can modulate the coupling efficiency of a probe light pulse. In the latter case, the spectral range is broadband in nature and covers telecommunication wavelengths.