Far-infrared laser
（重定向自FIR laser）
Far-infrared laser or terahertz laser (FIR laser, THz laser) is a laser with output wavelength in between 30-1000 µm (frequency 0.3-10 THz), in the far infrared or terahertz frequency band of the electromagnetic spectrum.
FIR lasers have application in terahertz spectroscopy, terahertz imaging as well in fusion plasma physics diagnostics. They can be used to detect explosives and chemical warfare agents, by the means of infrared spectroscopy or to evaluate the plasma densities by the means of interferometry techniques.