Periodic-structure photoexcitation of a silicon coplanar waveguide for selective optoelectronic microwave control

Presented is a detailed analysis of the microwave Bragg-reflection characteristics of a periodically continuous-wave (CW) photoexcited coplanar waveguide on silicon substrate, with special regard to the inherent carrier diffusion mechanisms. In particular, the carrier diffusion in the direction of wave propagation can strongly affect the stopband reflection spectra of the configuration with respect to magnitude and bandwidth or with respect to efficiency and selectivity. The dominant effects are studied quantitatively and are outlined in the form of practical performance diagrams. Future application of periodically photoexcited transmission line sections for light-induced tunable filters or Bragg reflectors can be inferred. Initial experimental results from a three-section periodic structure of 17-GHz-center frequency under 840-nm light emitting diode (LED) CW excitation are reported.>