This paper theoretically evaluates the external electro-optic (EO) sampling of high-speed electrical signals using poled polymers as materials for a proximity electric-field sensor. Based on the derivation of the half-wave voltage and the analysis of a static electric field coupled to the polymeric media placed over IC interconnections, invasiveness, voltage sensitivity, and spatial resolution have been discussed. The polymeric sensors have shown to be used in contact with the IC interconnections with negligibly small invasiveness, thus making polymeric sensors provide higher sensitivity and spatial resolution than inorganic crystals such as GaAs and KD*P.

The effect of sampling-pulse pedestals, generated by pulse compression, on the temporal resolution in electro-optic (EO) sampling is studied both theoretically and experimentally. Analysis is made on how the pedestals degrade a measurement bandwidth and a temporal waveform. Based on the analysis, a practical guideline on the suppression of pedestals is also given. Gain-switched laser diode (LD) pulses adiabatically soliton-compressed using a dispersion decreasing fiber are used to confirm the theoretical results, and are successfully applied to high-temporal-resolution (>100 GHz) EO sampling measurements.

A 300-GHz hetero-generous package solution with a combination of a polyimide microstrip-to-waveguide transition on low-temperature co-fired ceramic (LTCC) is presented. To assemble three parts — a metal back-short, polyimide transition, and LTCC substrate integrated waveguide (SIW) — a ridged microstructure beside the microstrip probe was implemented to reduce the air gap on the broadwall of a back-short. A back-to-back transition exhibited an insertion loss of 4.4 dB at 300 GHz and 49-GHz bandwidth with less than a 10-dB return loss. By evaluating loss of the microstrip line and SIW, we estimated the loss for a single transition, which was 0.9 dB at 300 GHz. The probe transition with ridged metal successfully suppressed the unwanted dip in transmission characteristics and eased the difficulty in assembly. The compact transition is easy to integrate in an antenna-in-package with an MMIC chip by combining suitable substrate materials for the transition and package.