Generating Polarized Light with Quantum Dots
Polarized light is extremely common in our world today, with displays and communication systems producing it, and sunglasses using it to protect our eyes. Polarizing filters work by absorbing the light that aligns in a specific direction, and the first filter light passes through absorb half of that light. Unfortunately that also means half of the energy is absorbed and wasted this way, but researchers at Linköping University have developed a way to directly produced polarized photons.
Quantum dots are semiconductive, nanoscale crystals that can be engineered to have specific properties. In this case the crystal is shaped like a pyramid and is mostly made of gallium nitride, a semiconductor. At its top though, some thin layers of indium are added, and it is from this indium that the polarized photons are released. When tested the researchers were able to produce photons with an average degree of linear polarization of 84%; a high value that could go higher.
As this system produces polarized photons directly, without the use of a filter, it could potentially lead to much more efficient devices than what we have now, including more efficient LCD monitors. The researchers also point out that because the quantum dots can produce a single photon at a time, it could be used in some quantum systems, such as those for quantum encryption.
Source: Linköping University