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Group velocity dispersion management in terahertz wireless communication channels

Strecker, Karl
High-fidelity models of the atmosphere from 0.1 to 1 THz based on spectroscopic databases are used to examine the effect of group velocity dispersion on ultra-wideband THz links. Previous spectroscopic characterization of THz channels predicts a limit on bit rate caused by group velocity dispersion, but spectroscopic characterizations are limited in their ability to account for important communication link parameters such as signal to noise ratio and maximum allowable symbol error rate. Realistic, statistical studies of the effect of atmospheric dispersion over the 0.2-0.3 THz wireless channel are presented, which account for these parameters and illustrate how future ultra-wideband THz communication systems may not be limited by loss, but by inter-symbol interference, stemming from group velocity dispersion.
A method to compensate atmospheric group velocity dispersion of terahertz pulses is also reported and demonstrated. In ultra-wideband terahertz wireless channels, the atmosphere reshapes terahertz pulses via group velocity dispersion, a result of the frequency-dependent refractivity of air. Without correction, this can significantly degrade the achievable data transmission rate. A method for compensating the atmospheric dispersion of terahertz pulses using a cohort of stratified media reflectors is presented. Using this method, group velocity dispersion in the 0.2-0.3 THz channel under common atmospheric conditions was compensated. Based on analytic and numerical simulations, the method can exhibit an in-band power efficiency of greater than 98% and dispersion compensation up to 99% of ideal. Design simulations were validated by experimental measurements.