Abstract

Signal propagation is studied by using transmission line loops 1 mm in diameter with cumulative propagation distances ≤6 cm. Amplitude and phase information is measured by using photoconductive pump-probe sampling and low temperature grown GaAs.¹ Propagation speeds are measured for temperatures 2 K < T < 295 K. The intrinsically low dielectric constant of coplanar-air transmission lines² is shown to result in high signal speed (0.9c) and half the attenuation of a conventional line. We verify the applicability of a model based largely on empirical formulae for radiation loss (geometry) and conductor absorption. The model is used to identify optimal design criteria (for a given bandwidth) and is applied for small dimensions.

© 1992 Optical Society of America