Electric-field observation of pico-pulse propagation on right-angle bends by miniature photoconductive near-field probe

The picosecond electric-pulse propagation characteristics on microstrip and coplanar waveguide right-angle bends have been successfully measured by mapping the time-dependent spatial electric near-field distributions. The measurement was performed using a 2-dimensional photoconductive (PC) electric near-field mapping system incorporating a new miniature PC electric-field probe, which was implemented on an optical fiber by coupling a PC switch on 1-mum-thick LT-GaAs epilayer to the end-facet of a 45degrees bevel-edge optical fiber. The probe could measure the three orthogonal picosecond electric-field components separately with minimal loading effects. The measured field-images showed quite remarkable transient picosecond electric-pulse propagation phenomena at the right-angle bends, which cannot be measured using conventional test instruments.