Investigation Of Liquid Properties On Emitting Terahertz Wave Under Ultrashort Optical Excitation

Liquid water was not considered as a favorable terahertz (THz) source due to its strongly absorption in THz frequency range. Recently, it has been experimentally demonstrated that broadband THz wave can be generated from liquid water under the excitation of ultrashort laser pulses. Here, we present the measured result of liquid lines as THz emitters. Selected liquids with different polarity, salinity and temperature on THz wave generation are investigated. Comparing with water with high polarity, lower polarity liquids produce stronger THz radiation with a broader bandwidth. a-pinene, a non-polar liquid produces strongest THz signals among all liquids we tested. Saline solutions produce weaker THz radiation compare to pure water. The THz signals from temperature with 8 degrees C, 18 degrees C, and 40 degrees C show marginal difference under our experiment's conditions. In addition, sugar, acid, alkali solutions and a variety of milks were also tested. Our observations show that non-polar liquids are in favor than polar liquid as alternative THz sources.