History and the state of the art of bulk modulators for EM measurements

Summary form only given. For the last fifteen years, a number of researchers have been applying the bulk crystal Pockels effect to construct antennas that can efficiently receive an electromagnetic (EM) signal without greatly perturbing the signal being measured. The author discusses the design parameters of such systems with particular emphasis on how these designs relate to the antenna characteristics. After briefly discussing some of the present problems in performing EM measurements with nonphotonic techniques, he considers how photonic sensors may solve some of these problems. In one application a system is examined that has short metallic dipole antennas directly coupled to the bulk crystals. This configuration is shown to have a minimum sensitivity of 1.7 mV/m per Hz/sup 1/2/ and a frequency bandwidth of 2.0 GHz. Eliminating the dipoles and using the bulk crystal as the antenna element by itself, a more compact, ruggedized, practical system has been built which has a minimum sensitivity of 40 V/m per Hz/sup 1/2/ and a frequency bandwidth of greater than 2.0 GHz. Such a system has many applications including fast rise-time EMP measurements.<>