Catching light

Willem Vos, Professor of Applied Physics at the UT, together with colleagues from Twente and Japan, have managed to design a thin, so-called, photonic crystal to trap and even manipulate light. The scientists found that their new slim design functions as well as traditional thick 3-D crystals. The thin size increases their application potential tremendously, for example, in the telecom industry, and in solar panels.

The science of manipulating and capturing light with photonic crystals is particularly fundamental. Yet, it offers different applications in many essential technologies of our modern society. According to Willem Vos, his newly designed photonic crystals are of particular industrial and scientific importance. Applications are numerous because of the crystal’s flat design, tiny volume and light weight.

For example, they may improve telecommunication. Since light contains more different wavelengths than traditional electrical signals, light can carry and transfer more different channels of information at the same time. An optical wire, guiding the light, can be combined with a fast optical switch that employs photonic crystals. This crystal switch may quickly reflect or block the incoming signal of a specific light color, resulting in the signal being passed, directed into another direction, or stopped altogether. Since this can be applied on the nanoscale and with extremely high switching speeds, more information can be processed with a single device. 

Increase absorption efficiency

Photonic crystals may also play a role in improving solar panels. To create an efficient solar cell, light waves should remain as long as possible inside the silicon top layer, so the silicon can optimally absorb the light and convert it into electricity. ‘If you manage to place a reflecting surface on the back of the solar cell, that preferably also redirects the light waves sideways in the silicon, the light waves travel farther inside the solar cell layer, resulting in an increased absorption efficiency,’ Vos explains. ‘Since photonic crystals are perfect mirrors for broad color ranges of light, our new flat design could very well be applied with very thin silicon solar cells. Here, they reflect the light inside the silicon in different directions, increasing light absorption and making solar panels more efficient.’

Keep reading…

You can read the full aticle written by Hans Wolkers here. This article makes reference to the paper “Reflectivity of three-dimensional GaAs photonic band-gap crystals of finite thickness” from Physical Review B. Read the original article here.