Jan 14 2019
Rare qualities in light have been exposed by scientists from the National Physical Laboratory (NPL) which could pave the way to completely new electronic devices and applications. Light is used widely in electronics for computing and telecommunications. Optical fibers are only one common example of how light is used to enable telephone calls and internet connections across the globe.
As described recently in Physical Review Letters, NPL scientists explored how light can be manipulated in an optical ring resonator, a miniature device that can store very high light intensities. Similar to certain “whispers” that can travel around a whispering gallery and be heard the other side, in an optical ring resonator, wavelengths of light resonate around the device.
The first-of-its-kind research uses optical ring resonators to identify the interplay of two types of spontaneous symmetry breaking. By examining how the time between pulses of light differed and how the light is polarized, the team has been able to expose new ways to control light.
For example, typically light will follow what is known as “time-reversal symmetry”, meaning that if time is reversed, light should travel back to its origin. However, as this study indicates, at high light intensities, this symmetry is broken within optical ring resonators.
Francois Copie, a scientist on the project explains: “When seeding the ring resonator with short pulses, the circulating pulses within the resonator will either arrive before or after the seed pulse but never at the same time.”
As a promising application, this could be used to integrate and rearrange optical pulses, for example, in telecommunication networks.
The research also revealed that light can suddenly change its polarization in ring resonators. This is as if a guitar string was primarily plucked in the vertical direction but abruptly starts to vibrate either in a clockwise or an anticlockwise circular motion.
This has not only enhanced researcher’s understanding of nonlinear dynamics in photonics, aiding to guide the creation of better optical ring resonators for future applications (such as in atomic clocks for exact time-keeping) but will help researchers to properly understand how light can be controlled in photonic circuits in sensors and quantum technologies.
Optics have become an important part of our telecoms networks and computing systems. Understanding how we can manipulate light in photonic circuits will help to unlock a whole host of new technologies, including better sensors and new quantum capabilities, which will become ever more important in our everyday lives.
Pascal Del’Haye, Senior Research Scientist, National Physical Laboratory (NPL)