Optical design and numerical modelling of all-dielectric optoelectronic sensor for high power electric fields measurements

摘要

We discuss the optical configuration and present mathematical modelling of intense electric fields sensor. The device is dedicated for the measurements of high power electromagnetic pulses (HPM) magnitude. For this reason, the sensor head has been designed as all-dielectric component, in order to avoid interferences with the measured fields. The laser source and detector unit are joined with the head through long optical fibres and the whole system utilizes 1.5 μm telecomm fibre technology. The sensor operation is based on Pockels effect induced by electric component of EM wave in bulk LiNbO_3 crystal. Collimated laser beam propagating through the crystal is obtained by the application of miniature GRIN lens attached to the end of the fibre. Similarly, the fibre coupling of the beam after it crosses the crystal, is obtained. In the paper the focus is also put on mathematical foundations of full 3-dimentional sensing of E-field, which would enable to measure not only the magnitude, but also to determine the direction to the HPM source.