Fiber optics allow for the communication of data at the speed of light. But the amount of data that can be sent along any optic fiber is limited by how much information you can encode into the light wave travelling through it. Currently, optic fiber technology uses several different properties of light to encode information, including brightness, color, polarization and direction of propagation. But if we want to cram even more information through optic fiber, we need to use other features of light to encode more information, without disrupting the currently used properties. Such a feature could help boost the bandwidth of optic fiber technology, including our internet speed.
If the light wave travelling through the optic fiber is twisted helically – like a spring – then it has an angular momentum, which is a measure of its momentum when it rotates around a point. But there was a major problem with using angular momentum to decode the information from the optic fiber in the past. We needed a material with tiny nanoscale helical structures that could detect the twisted light when present.
A research team now published in Science, how the angular momentum of light at a nanoscale can be controlled by using an integrated photonic chip. So for the first time, we have a chip with a series of elaborate nano-apertures and nano-grooves that allow for the on-chip manipulation of twisted light.
The helical design of these tiny apertures and grooves removes the need for any other bulky interference-based optics to detect the angular momentum signals. So if you send an optical data signal to a photonic chip, which is a microchip that uses light instead of electrons, then it is important to know where the data is going, otherwise information will be lost. Using this type of a nanophotonic chip, the researchers could precisely guide angular momentum data signals without losing the information they carry. What’s more, the angular momentum information of many different signals can be processed at the same time through the chip. This means we can potentially achieve an ultra-wide bandwidth, with six orders of magnitude of increased data access compared to current technology.