Modeling and Experimental Characterization of Microwave Propagation Properties in Laser-Induced Solid-State Plasma in Silicon Waveguides at 140–220 GHz

This paper presents the modeling and experimental characterization of the microwave properties of laser-induced solid-state plasma in silicon dielectric waveguides at 140-220 GHz. Lasers with wavelengths of 1550, 1064, 980, 852, 785, 685, 520, and 405 nm are used at different laser intensities to investigate their effects on electromagnetic wave propagation. An improved analytical model is developed to accurately predict the behavior of laser-induced solid-state plasma, taking into account wavelength and intensity-dependent excess carrier generation, and the resulting depth-dependent conductivity and permittivity. The analytical results are implemented in a multi-layer simulation model in CST Studio Suite to simulate full-wave electromagnetic propagation. The 980 nm laser achieves the largest attenuation, reaching up to 67 dB at 20 W/cm2at 200 GHz. The simulation results show excellent agreement with experimental measurements, confirming the validity the analytical and simulation models.