German and Indian physicists have discovered that ultra-thin two-dimensional materials such as tungsten diselenide can rotate the polarisation of visible light by several degrees at certain wavelengths under small magnetic fields, making them suitable for use on chips. This property is crucial for optical isolators, which allow light to propagate in one direction but block all light in the other direction. Conventional isolators are quite large, preventing the creation of miniaturised integrated optical systems on a chip comparable to silicon-based electronic technologies. The German-Indian team’s work represents a significant development towards miniaturised optical isolators, as the 2D materials used are only a few atomic layers thick.
Prof Rudolf Bratschitsch from the University of Münster and Prof Ashish Arora from IISER believe that two-dimensional materials could become the core of optical isolators, enabling on-chip integration for current optical and future quantum optical computing and communication technologies. They suggest that even the bulky magnets required for optical isolators could be replaced by atomically thin 2-D magnets, drastically reducing the size of photonic integrated circuits. The team deciphered the mechanism behind their discovery, finding that bound electron-hole pairs, or excitons, in 2D semiconductors rotate the polarisation of light strongly when placed in a small magnetic field. However, conducting such sensitive experiments on two-dimensional materials is challenging due to their small sample areas, requiring the development of a new, faster measuring technique.
The ability of 2D materials to rotate the polarisation of light has significant implications for the field of optical communication networks, as it could lead to the development of more compact and efficient optical isolators for use in integrated optical chips. Currently, integrated optical chips consist of only a few hundred elements, limiting their potential for miniaturisation and integration with existing electronic technologies. By utilising ultra-thin 2D materials, researchers could pave the way for the development of smaller, more powerful optical components that can be integrated into a wide range of devices.
The findings of the German-Indian team offer promising opportunities for advancements in optical computing and communication technologies, as well as quantum information processing. By harnessing the unique properties of 2D materials, researchers may be able to overcome current limitations in optical isolator technology and enable the creation of more efficient and compact integrated optical systems. This could revolutionise the field of photonics and pave the way for the development of next-generation optical devices that are smaller, faster, and more versatile than ever before.
In conclusion, the discovery of the ability of ultra-thin two-dimensional materials to rotate the polarisation of visible light under small magnetic fields represents a significant breakthrough in the field of photonics. By developing new techniques and harnessing the unique properties of 2D materials, researchers may be able to revolutionise the design and performance of optical isolators, enabling the miniaturisation and integration of optical components on chips. This could pave the way for the development of more efficient and powerful optical computing and communication technologies that are capable of meeting the demands of future quantum information processing and other applications.
