An aperture-type near-field optical microscope based on hollow-pyramid cantilevered probes has been developed and optimized for ultrafast nonlinear nanospectroscopy applications. These probes have many advantages for near-field microscopy such as higher throughput, higher thermal damage threshold, and absence of pulse chirping. The input pulse duration (as short as 30 fs from a mode-locked, stretched cavity 26 MHz Ti:Sapphire oscillator) is maintained beyond the aperture. Such short pulses, combined with the high peak powers available at the output of hollow-pyramid probes, allow experiments of nonlinear microscopy and spectroscopy with higher spatial and temporal resolution as compared to similar experiments based on optical fiber tips. Results on second-harmonic generation by gold nanostructures and BBO nonlinear crystals are reported demonstrating a spatial resolution down to 100 nm with 40 fs pulses. Implications for local femtosecond time-resolved pump-probe spectroscopy are anticipated.

Date Published: 18 August 2005
PDF: 7 pages
Proc. SPIE 5927, Plasmonics: Metallic Nanostructures and Their Optical Properties III, 592710 (18 August 2005); doi: 10.1117/12.626337

Published in SPIE Proceedings Vol. 5927:
Plasmonics: Metallic Nanostructures and Their Optical Properties III
Mark I. Stockman, Editor(s)