THz Liquid Photonics
The four fundamental states of matter include solid, liquid, gas, and plasma. In the field of THz research, THz radiation generating from solids, gases, and plasmas has been well demonstrated and studied for decades. Yet, the generation of THz waves from liquid, especially liquid water or its plasma, is rarely discussed due to water’s extremely strong absorption across the THz frequency range. After yearslong study and experiment, our lab has found a way to generate broadband THz waves inside liquids.
THz Air Photonics
One of the most used THz generation schemes is the air-plasma generation. It is achieved by focusing a high-intensity femtosecond laser in air. It has been proved that the use of air, instead of nonlinear crystals or ultrafast antennas, as both the emitter and the sensor lead to development of THz systems with unprecedented broad bandwidth and high peak electric field with application in imaging, linear and nonlinear material characterization. Moreover, using this techniques, remote generation and detection of THz waves is feasible, therefore one can envision standoff detection of threat or hazardous substances.