Ultra-wideband GCPW-CMS-GCPW transition for characterization of all-optical ADCs based on leaky waveguide deflector

Design of an all-optical analog-to-digital converter (AOADC) is presented here based on a leaky waveguide deflector in electro-optic (EO) polymers driven by a coupled microstrip (CMS) line. In particular, back-to-back transitions from grounded coplanar (GCPW) to microstrip line (MS) and from microstrip to CMS line, permitting to connectorize and characterize the EO deflector, are presented. The best achieved bandwidth is over 53 GHz with a remarkably lower cutoff frequency of only 2 GHz. This transition, without via-hole, using electromagnetic coupling between the bottom and top ground planes simplifies the manufacturing and facilitates the characterization of component by means of coplanar probes.