Hollow-pyramid based scanning near-field optical microscope coupled to femtosecond pulses: a tool for nonlinear optics at the nanoscale.
We describe an aperture scanning near-field optical microscope (SNOM) using cantilevered hollow pyramid probes coupled to femtosecond laser pulses. Such probes, with respect to tapered optical fibers, present higher throughput and laser power damage threshold, as well as greater mechanical robustness. In addition, they preserve pulse duration and polarization in the near field. The instrument can operate in two configurations: illumination mode, in which the SNOM probe is used to excite the nonlinear response in the near field, and collection mode, where it collects the nonlinear emission following far-field excitation. We present application examples highlighting the capability of the system to observe the nonlinear optical response of nanostructured metal surfaces (gold projection patterns and gold nanorods) with sub-100-nm spatial resolution.
Celebrano
Michele
M
Dipartimento di Fisica, National Laboratory for Ultrafast and Ultraintense Optical Science-CNR-INFM, Politecnico di Milano, P.za L. da Vinci 32, 20133 Milano, Italy. michele.celebrano@phys.chem.ethz.ch
Biagioni
Paolo
P
Zavelani-Rossi
Margherita
M
Polli
Dario
D
Labardi
Massimiliano
M
Allegrini
Maria
M
Finazzi
Marco
M
Duò
Lamberto
L
Cerullo
Giulio
G