TU Delft demonstrates for the first time how light squeezes through small holes

How does light pass through a tiny hole" For the first time, Dr Aurele Adam and Prof. Paul Planken of Delft University of Technology, in conjunction with two South Korean and one German research groups, have succeeded in mapping this process properly. Their research also promises a significant improvement in Terahertz microscopy in the long term, a potentially interesting new imaging technique, and Terahertz microspectroscopy, a technique for identifying tiny quantities of substances using light. Their findings will be published in the scientific journal Optics Express this week.

We know from physics that it is particularly difficult to pass light through a hole smaller than half the wavelength of the light used. With the help of fellow scientists, researchers at Delft University of Technology have managed to provide insight into this process by conducting measurements using what is known as Terahertz radiation (THz radiation). This is far-infrared light with an approximate frequency of 1012 Hz. This type of radiation allows the researchers to measure the force of the penetrating light’s electrical field near the hole and not, as is usual, the intensity of the penetrating light. The electrical field’s values reveal much more about how light behaves in such situations than intensity can. Measurement of the strength of the electrical field is done with great precision by measuring the refractive-index of a crystal near the hole using a laser beam. The crystal’s refractive index varies (very slightly) when in a variable electrical field. By measuring the variations in the refractive index, conclusions can be drawn on the strength of the light’s electrical field near the hole.

Bouwkamp