Terahertz laser light focused to the extreme

There are limits to how short a flash of light can be – in both time and space. Researchers from the Paul Scherrer Institute (PSI) have now succeeded in reaching these physical limits and producing the smallest possible flash. To do so, they used terahertz light, which is physically related to visible light or radio waves, but differs in its wavelength. In the experiment, a special crystal was illuminated with laser light and thus stimulated to emit terahertz light, which a mirror system subsequently focused to generate a highly concentrated flash. The challenge was to actually produce the terahertz light at a high enough quality for it to be focused. Highly intensive terahertz light is becoming increasingly important as a research tool because it can be used to specifically alter the behaviour of materials and study their properties. Read the full Story