We demonstrate two approaches to characterize the femtosecond laser light based on use of: (a) localized plasmon oscillations in a single metal nanostructure, (b) interference of surface plasmon waves propagating on monocrystalline Au nanofilm.
At present, the measurement of ultrafast, on a femtosecond time scale, optical fields with a nanometer spatial resolution still seems to be a challenging problem. Measurement of ultrafast optical pulse with a nanoscale spatial resolution is even a more challenged problem [1].
Figure 1. Schematic diagram of the setup for the measurement of spatio-temporal properties of femtosecond laser radiation using a single plasmon SHR nanostructure.
We propose and realize a new concept of a nanoprobe for the characterization of femtosecond laser pulses, which is based on a giant optical nonlinearity of plasmonic nanostructure [2] (Fig. 1). As a nanostructure, we use a split hole resonator (SHR), which was made in an aluminum nanofilm (Fig. 1). The SHR nanostructure ensures a high nonlinear optical efficiency of the interaction with laser radiation, which leads to the second and the third harmonics generation which, in turn, are used to perform multi-order autocorrelation measurements [3]. The nano-sized SHR make it possible to conduct autocorrelation measurements (i) with a subwavelength spatial resolution and (ii) with no significant influence on the duration of the laser pulse.
Femtosecond plasmonic interferometry based on a geometry slit – grove on the monocrystalline Au(111) surface is demonstrated. The plasmonic microinterferometer consists of a tilted slit-groove pair. This arrangement allows us to perfprm: (1) the measurements of real and imaginary parts of the metal dielectric function of Au(111) nanofilm, and (3) the measurements of the femtosecond laser pulse duration in several periods of light oscillations (6 fs).
References:
[1] L. Sarger and J. Oberl_e, in Femtosecond laser pulses, C. Rulliere, eds. (Springer, 2005), p 204.
[2] P. N. Melentiev, A. E. Afanasiev, A. A. Kuzin, A. S. Baturin, and V. I. Balykin, Opt. Express v. 21, 13896 (2013).
[3] P.N. Melentiev, A.E. Afanasiev, A.V. Tausenev, A.V. Konyaschenko, V.V. Klimov and V.I. Balykin, Laser Phys. Lett. v.11, 105301 (2014).
afanasiev.isan@gmail.com