Structured light self-image in cylindrical systems reveals a new form of space-time duality

Photonics researchers at the University of Tampere in Finland and the Kathler Brossel Institute in France have shown that self-image of light, a phenomenon known in nearly two centuries, has been applied to cylindrical systems, and unprecedented control of the structure of light. We have demonstrated that it can be promoted. Advanced optical communication system. Additionally, new types of space-time duality have been investigated due to powerful analogs that bridge fields of different optical fields.

In 1836, Henry F. Talbott conducted an experiment. There, we observed light patterns that were naturally reproduced after propagation without using lenses or imaging optics.

Recently, researchers interested in sculpture at the University of Tampere’s Experimental Quantum Optical Group (EQO) and Kastler Brossel Laboratory’s complex media optics group at Ecole Normal Superior in Paris combine self-image Talbot. I investigated it. Effects in cylindrical systems with deeper depths than ever before. Currently, interesting fundamental physics and powerful applications in optical communications are featured in Journal Nature Photonics.

Exploring the effects of self-image in cylindrical geometry

Light at the so-called ring core fiber experiences a self-imaging process, albeit at an angle position.

“When light enters the fiber at a specific angular position of a ring-like fiber core, it first spreads across the cylindrical core, then completely recombine to form the original field through a self-image process. “We’re doing this,” explains doctoral researcher Matias Eriksson. One of the leading authors of the study.

Importantly, this self-image at angular position is only half of the fundamental phenomenon of cylindrical geometry. A similar interference effect is also manifested in the closely related properties of light known as orbital angular momentum. This allows light to orbit around the optical axis, that is, via a ring-like path. Essentially, both properties, angular position, and orbital angular momentum are considered complementary variables. In other words, the exact definition of one characteristic leads to the inaccuracy of another characteristic.

The team is now combining angles and orbital angular momentum for the first time in a single experiment for the first time, for unprecedented control of the light’s spatial structure. However, this study does not stop there, and researchers will also explore interesting connections to the time domain and demonstrate powerful applications for optical communication.

Bridge two popular fields of optics

The basic idea of ​​optics is the so-called duality of space-time. This suggests that many spatially observed effects are also seen in the temporal structure of light. Based on this principle, a generalized self-image of time is a periodic sequence of light pulses and a comb of corresponding frequencies, i.e. light containing only well-defined equally spaced frequencies, i.e. light, i.e. light. It only occurs.

In their study, researchers reveal new forms of space-time duality by showing a strong link between angular/angular momentum and time/frequency.

“This means that the physical phenomena observed in these two areas are widely connected and one processing technique can be used for the other,” said a postdoctoral fellow at the Kasler Brossel Institute. He is currently a researcher at the Ecole Polytechnic Federare des Lausannes in Switzerland.

The basic effect triggers applications to optical communication

With the benefit of this deeper, underlying insight into self-image and its associated advanced modulation capabilities, researchers have further demonstrated powerful applications for optical communication.

“Generalized self-image effects can be cleverly tuned to encode, transform and decode information of light’s orbital angular momentum values ​​so that they function as an independent communication channel,” says Ericsson.

Therefore, the current study shows that the theoretical promise of lossless crosstalk-free operations for a significant increase in data rates is within reach and could have a significant impact on the future of optical communications. indicates.