In a recently published study in Light: Science & Applications , a team of scientists led by Professor Lixin Guo from Xi’an shared their insights into the history and future of optical measurements using orbital angular momentum (OAM). The study delves into the fundamental concepts, applications, and key developments in the field.
Metrology is the foundation of modern industry and provides the primary standard by which the world is measured. Optical metrology in particular has historically relied on the concept of interference, a concept that has remained intact since the time of Thomas Young over 200 years ago. Can we learn more by applying the fringe concept to other degrees of freedom?
By using a modern interpretation of the Doppler effect to observe a frequency shift that depends on both OAM and polarization, the researchers show how twisted light carrying OAM can be used for new measurement models, such as 3D particle position tracking.
While the original Doppler effect could only track motion toward or away from an observer, by incorporating orbital angular momentum into both scalar and vector light, it is now possible to track motion in all directions, including rotational motion. This advance has revolutionized the measurement of dynamical systems.
Andrew Forbes, corresponding author of the study and professor at the University of the Witwatersrand
This field is driven by a paradigm shift in existing tools and the development of entirely new tools, one example of which is the concept of the OAM spectrum serving as the “signature” of the system: when OAM light passes through a complex medium, its OAM is modified, changing the shape of the OAM spectrum.
“A vehicle’s OAM fingerprint contains a wealth of information that can be exploited ,” added lead author Dr Minjian Chen.
According to the review, the interpretation of OAM spectra through machine learning and AI is a rapidly growing field, paving the way for real-time analysis and identification of complex materials where OAM light acts as a probe.
This review covers metrology using classical light as well as the use of OAM in quantum superposition and single photon states. Moving into the quantum regime has the potential to reduce noise while increasing precision and reliability with fewer observations, although elements of this subject are still in the early stages of development.
“Quantum metrology using OAM is an emerging field with many untapped opportunities ,” Forbes added.
This comprehensive review covers a wide range of applications, from tiny nanosensors to measuring black holes in space. This is an authoritative summary that will be useful to both new and experienced researchers.
Journal References:
Cheng, M., et al. (2025) Metrology with a twist: Probing and sensing with swirling light. Light: Science and Applications . doi.org/10.1038/s41377-024-01665-1
sauce:
Changchun Institute of Precision Physics, Mechanics and Optics
