Sub-20-fs Time-Resolved Measurements in an Apertured Near-Field Optical Microscope Combined with a Pulse-Shaping Technique

We have constructed an ultrafast near-field optical microscope system with near-field pump/probe pulses with a 17 fs duration at the probe tip. The dispersion effects arising from the optical components, especially from the optical fiber, were removed by a pulse-shaping system that consists of passive and adaptive group-velocity dispersion compensators. With this apparatus, we succeeded in measuring dephasing in a single gold nanostructure with a time constant on the order of 10 fs. (C) 2012 The Japan Society of Applied Physics