TEMPERATURE PROFILE OF FIBER TIPS USED IN SCANNING NEAR-FIELD OPTICALMICROSCOPY

We have measured the temperature profile of aluminum coated fiber tips used for illumination-mode scanning near-field optical microscopy as a function of the optical input power with a micron sized thermocouple . The temperature coefficients vary from 20 K/mW for tips with a large cone angle to 60 K/mW for the narrow long ones. Temperatures of up to approximate to 470 degrees C have been measured close to the aperture with an optical input power of several mW before thermal damage of th e coating occurred. The temperature profiles are analyzed theoreticall y taking into account the optical absorption, the thermal conductivity of the tip, as well as the heat loss to the environment. (C) 1996 Ame rican Institute of Physics.