Terahertz radiation

Terahertz radiation is electromagnetic radiation with frequencies roughly from 0.1 to 10 terahertz, between microwaves and infrared light. Its waves can probe molecular motions and pass through some nonconductive materials.

Terahertz time-domain spectroscopy: A spectroscopy method that measures terahertz electric fields over time to determine a material’s frequency-dependent response. It turns short terahertz pulses into measurements of material properties across a broad frequency range.
Terahertz imaging: Imaging that uses terahertz radiation to map objects or materials from their transmitted, reflected, or emitted signals. It exploits terahertz penetration and material contrast for non-destructive inspection.
Electromagnetic spectrum: The full range of electromagnetic radiation, ordered by frequency or wavelength. Terahertz radiation occupies the transition between microwave and infrared regions.
Microwave: Electromagnetic radiation with wavelengths commonly ranging from about one meter to one millimeter. Terahertz radiation lies above the usual microwave band in frequency.
Photoconductive antenna: An optically switched semiconductor device that emits or detects electromagnetic radiation through transient currents. Femtosecond laser pulses drive these antennas to generate and sample terahertz pulses.
Terahertz spectroscopy: The study of matter by measuring its interaction with electromagnetic radiation in the terahertz frequency range. Many molecular rotations, lattice vibrations, and collective excitations respond in this band.
Frequency: The number of cycles of a periodic event occurring per unit time. Terahertz frequencies correspond to trillions of oscillations each second.
Infrared: Electromagnetic radiation with wavelengths longer than visible light and shorter than microwaves. Terahertz radiation borders the far-infrared region, whose boundary conventions vary.
Optical rectification: A nonlinear optical process in which an oscillating optical field creates a low-frequency polarization in a material. It converts ultrashort laser pulses into terahertz radiation in nonlinear crystals.
Terahertz communication: Wireless communication using carrier frequencies in the terahertz range. The broad available bandwidth could support high data rates over short distances.

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