New non-disturbing and wideband optical microsensor of electromagnetic fields

A new non-disturbing photonic for measuring electromagnetic (EM) power is presented. The sensing element is made of a silicon Fabry-Perot optical microcavity connected to an optical fiber for remote interrogation. Preliminary measurements have been carried out in a non-optimized prototype in the frequency range 2-18 GHz. They have shown the capability to detect minimum EM power densities of approximately 1.4 mW/cm 2, and a flat response at frequencies greater than 10 GHz. A proper calibration makes the sensor useful as an E-field probe. In this case, resolutions as low as 8 V/m have been measured. A simple theoretical analysis giving results in fair agreement with the experiments is also reported. Simulations show that wide margins of optimizations of the sensor exist.