A finite photonic crystal nanostructure in free space. The photonic crystal consists of periodic arrangements of pores in a semiconductor material such as silicon (shown in grey) that are being fabricated in Twente. Light noise in the surrounding free space is shown as the red wavelets. For a range of colours of light (known as the photonic band gap), the light noise is forbidden from entering the crystal, thus leading to strong darkness. The question solved in Twente is: How fast is absolute darkness reached while making the nanostructure larger and larger? Courtesy: University of Twente
Topics: Applied Physics, Nanotechnology, Optics, Photonics
Just as there is no such thing as a complete vacuum, there is no such thing as complete darkness. This is because there are always continuous fluctuations of light in space, also known as light noise. Theory predicts that this light noise might be completely eliminated in photonic crystals, however, so allowing them to become absolutely dark.
Photonic crystals are nanostructured materials in which a periodic variation of the refractive index on the length scale of visible light produces a photonic “band gap”. This gap affects how photons propagate through the material and is similar to the way in which a periodic potential in semiconductors affects the flow of electrons by defining allowed and forbidden energy bands. In the case of photonic crystals, light of certain wavelength ranges can pass through the photonic band gap while light in other ranges is reflected.
Photonic crystals follow a straight path to absolute darkness, Belle Dumé, Physics World