Broadband microwave dielectric measurements with optoelectronically generated picosecond transient radiation

Summary form only given. The coherent microwave transient spectroscopy (COMITS) technique and its application to the characterization of the complex dielectric properties of materials in the 15-140-GHz frequency range were discussed. The COMITS technique is based on freely propagating electromagnetic pulses radiated and received by broadband antennas integrated with high-speed optoelectronic devices. Ultrashort optical pulses are used to generate the picosecond-duration electrical pulses which drive the antennas and to sample the received waveforms photoconductively. The COMITS experimental setup has been used to characterize low-loss materials such as Teflon, and materials of interest to the digital electronics industry such as polyimide and ceramics. It has been extended to characterize the properties of thin polymer films and to explore the dispersion properties of novel photonic-band structure samples. A reflection-COMITS configuration has been developed to characterize lossy materials such as doped semiconductors.<>