External electro-optic measuring system with high spatial resolution and high voltage sensitivity by using an electro-optic solid immersion probe

A GaAs hemisphere has been used for the first time both as a probe and a solid immersion lens in a reflecting external electro-optic measuring system to substantially improve the spatial resolution and the voltage sensitivity of the system. The electric signals propagating on microstrip lines were detected successfully. In contrast with a conventional cubic probe under the same measuring conditions we found that the voltage sensitivity of the measuring system with the hemispherical probe was improved by a factor of nearly 1.7 to 3 mV Hz(-1/2), and the spatial resolution was improved by a factor of 4.5 to 0.6 mum. The improvements in the spatial resolution and voltage sensitivity are due to the increased effective number aperture and the total internal reflection in hemispherical GaAs probe, respectively.