Phys.org January 4, 2021
Due to material imperfections, some amount of light is reflected backwards in microresonators which disturbs their function. To reduce the unwanted backscattering an international team of researchers (UK, Germany) used the principle of noise cancelling headphone and introduced out-of-phase light to cancel out optical interference. To generate the out-of-phase light, the researchers position a sharp metal tip close to the microresonator surface. The tip also causes light to scatter backwards. As the phase of the reflected light can be chosen by controlling the position of the tip, backscattered light’s phase can be set so it annihilates the intrinsic back reflected light. They demonstrated a record suppression of more than 30 decibels compared to the intrinsic back reflections. The method can be used to improve gyroscopes, improve portable optical spectroscopy systems, opening for scenarios like built-in sensors in smartphones for detection of dangerous gasses or helping check the quality of groceries, and transport more information even faster…read more. Video  Open Access TECHNICAL ARTICLEÂ
Experimental setup and example measurements. Credit: Light: Science & Applications volume 9, Article number: 204 (2020)