From Event: SPIE Commercial + Scientific Sensing and Imaging, 2018
Long-distance propagation of THz pulses is important to THz communication and monitoring pollutants and dangerous gases. The THz pulses are propagated through 186 m and 910 m distance which are approximately equal to 52 and 255 round-trips of the circulating 50 fs optical pulse within the mode-locked ring laser, respectively. When the humidity and temperature are continuously varied during the measurement, the THz pulses also continuously shifted with 2.36 and 15.53 ps/(g/m3) ratio for a 186- and 910-m propagation, respectively. The complexity of the atmosphere required the use of the complete theory of Essen and Froome to compare the measured time shifts due to both the dry atmosphere and water vapor with theoretical calculations. When the THz pulses were sequentially measured for a distance of 186 and 910 m at the same weather condition, the time variation due to atmospheric turbulence between the two pulses of the 910 m measurement was up to 4 times larger than that between the two pulses of the 186 m measurement.
Meanwhile, the characteristics of the N2O and CO gases are investigated 93 meters away from the THz transmitter using the THz pulse which propagates an outside environment of 79 m between two buildings. The natural resonances of the gases are detected in the 0.5 THz bandwidth except water vapor resonances.
Tae-In Jeon, "Long-distance propagation and gas sensing using THz pulses (Conference Presentation)," Proc. SPIE 10657, Next-Generation Spectroscopic Technologies XI, 1065712 (Presented at SPIE Commercial + Scientific Sensing and Imaging: April 18, 2018; Published: 14 May 2018); https://doi.org/10.1117/12.2304505.5783312889001.
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