THz
terahertz
Frequencyexact by definition
The terahertz is 10¹² hertz. It names the band between microwaves and infrared, roughly 0.1 to 10 THz, which sat undeveloped for decades because it was too fast for electronics and too slow for optics. Terahertz imaging now sees through clothing, paper and plastics without ionising anything.
| 1 THz | 1,000,000,000,000 Hz |
Where the unit came from
The gap was called the "terahertz gap" precisely because neither transistors nor lasers reached it. Photoconductive antennas and quantum cascade lasers closed it from both sides in the 1990s and 2000s.
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