PARAMETER CONTROL, CHARACTERIZATION, AND OPTIMIZATION IN THE FABRICATION OF OPTICAL-FIBER NEAR-FIELD PROBES

Tip diameter and transmission efficiency of a visible-wavelength near- field optic probe determine both the lateral spatial resolution and ex perimental utility of the near-field scanning optical microscope. The commonly used tip fabrication technique, laser-heated pulling of fused -silica optical fiber followed by aperture formation through aluminiza tion, is a complex process governed by a large number of parameters. A n extensive study of the pulling parameter space has revealed a time-d ependent functionality between the various pulling parameters dominate d by a photon-based heating mechanism. The photon-based heat source re sults in a temperature and viscosity dependence that is a complex func tion of time and fiber diameter. Changing the taper of the optical pro be can affect transmission efficiency by an order of magnitude or more .