Single shot measurements of the E-field vector with pigtailed optical probes
Summary form only given. Over the variety of available sensors dedicated to electric (E)-field characterization, the use of antennas constitutes the most widespread technique. While such probes are convenient and provide a good sensitivity, they remain invasive and bandwidth limited. At the opposite, fibered electro-optic transducers1 are fully dielectric, millimeter sized and allow to perform measurements of the E-field vector from DC to several gigahertz and even up to terahertz frequencies using equivalent-time sampling. Furthermore, recent developments lead to a simultaneous characterization of 2 transverse E-field vector components with a single EO probe2. Based on polarization state modulation, the EO transducer is linked to a remote (up to 30 meters) optoelectronic set-up including a ultra low noise laser feeding the probe and a real time optical set-up to manage the modulation treatment. The automated and servo controlled measurement bench is temperature dependent free. The available measurement dynamics exceeds 100 dB, ranging from less than 1 V. m-1. Hz-1/2 up to the breakdown electric field in air.An exhaustive comparison between BO sensors and other technologies will be firstly given during the conference. This analysis will be based on intrinsic sensor properties, such as sensitivity, frequency bandwidth, vectorial selectivity, spatial resolution and induced perturbation on the field to be measured. After recalling the principles of the BO effect, the optical arrangement of the optical probes will be described. The characterization of the BO system will be presented together with experimental results illustrating the potentialities of BO sensors. Among these examples, measurements of pulsed B-field in air (pulsed power), water (specific absorption rate evaluation in pulsed regime) or in plasma (real time evolution of the electrical discharge associated B-field) will be shown.
Electro-optic sensors for electric field measurements. II. Choice of the crystals and complete optimization of their orientation
We present a simple method to determine both direction of the electric field component to which an electro-optic sensor is sensitive and sensitivity to this component. For this purpose we introduce the concept of an electro-optic sensitivity vector. This work is done for electro-optic sensors working as amplitude modulators, as phase modulators, or as polarization state modulators. The method applies to any anisotropic crystal, regardless of crystallographic group. After defining three kinds of electro-optic sensor geometry that allow longitudinal, transversal or fully vectorial electric field probing, we make a comparative study of several commonly used electro-optic crystals. We derive the optimal orientations of the crystals with respect to the optical probe beam that lead to high-performance electro-optic sensors. We also treat isotropic crystals in the case of polarization state modulators. In contrast to anisotropic crystals that are sensitive to a unique electric field component, we show that isotropic crystals are sensitive to two orthogonal electric field components simultaneously.
Two-dimensional field mapping of monolithic microwave integrated circuits using electrooptic sampling techniques
Since the invention of the electrooptic sampling technique about ten years ago, this contactless test technique based on ultra-short optical pulses has become more and more attractive to microwave engineers developing monolithic microwave integrated circuits (MMICs). The electrooptic sampling technique was originally used for circuit internal measurements of very high-speed waveforms only at discrete test points. During the last five years, a new test technique, the two-dimensional electrooptic field mapping technique, has been developed and widely used. This test technique which measures the magnitude and phase of the microwave signal gives information not only of one discrete test point but also of a greater area within the circuit and therefore insight into the microwave field distribution. This two-dimensional electrooptic field mapping technique could be a powerful tool for studying fundamental properties of wave propagation in monolithic integrated microwave devices and circuits. The aim of this paper is to present the state-of-art of this new test technique and to show an example of its application.