A FIBEROPTIC SENSOR FOR MICROWAVE FIELD-MEASUREMENTS

A fiber-optic sensor for weak interaction measuring of the electric field intensity in microwave fields is presented. The most remarkable features of the sensor are a low isotropy error, a good selectivity between the electric and magnetic field component, a high sensitivity, low field distortions, and inexpensive fabrication. A tiny microwave absorber mounted at the end of an optical fiber changes its temperature according to the electric field intensity. The absorber temperature is measured by making use of the optical transmittivity variation of a semiconductor element. A simple evaluation of the optical attenuation leads to a readout which is proportional to the square of the electric field strength. In order to overcome the problems due to fiber bend losses a mode acceptance filter is described. (C) 1995 American Institute of Physics.