Optical heterodyne characterization of high speed devices using near-field fiber optic probes

Near field fiber optic probes have attracted a great deal of current interest mainly due to their ability to extend optical microscopy beyond the classical diffraction limit. Scanning optical microscopes using these probes have been yielded very high resolution in imaging and spectroscopic applications at visible and infrared wavelengths. The technology has been applied to imaging in biology, material science, surface chemistry and information storage. In this work, we explore a novel use of the near field fiber optic probes in optical heterodyne characterization of high speed devices. Because of the submicron feature size of modem electronic devices, conventional optical heterodyning only yields the response of the device as a whole. Introducing near field fiber optic probes allows one to examine spatially resolved details of device response and thereby provides a means to look more closely at the internal carrier dynamics. Our technique thus comprises an important tool for the experimental study of ultrafast devices.