Synopsis: Coupled Solitons Jiggle Like Molecules

Pairs of solitons traveling in an optical fiber behave like a vibrating molecule.
Synopsis figure
K. Krupa et al., Phys. Rev. Lett. (2017)

A soliton is a pulsed waveform that maintains its shape as it travels. If multiple solitons travel in a medium, their mutual attraction can cause them to form bound states that can be seen as “molecules.” Experiments, however, haven’t yet established what molecular properties could be extended to solitons. A team led by Philippe Grelu of the University of Burgundy, France, has now shown that soliton molecules can vibrate like real molecules.

Previous studies using time-averaging methods delivered indirect signatures of soliton molecule vibrations but could not follow the motion of individual solitons. Using a method developed by others, the authors observed soliton light pulses produced by a fiber laser on a shot-to-shot basis, removing the need for averaging. The scheme sends solitons into a fiber that adds a frequency-dependent delay, converting the spectrum of each pulse into a temporal waveform measurable with a fast detector. The results showed that the soliton molecules exhibited two types of internal motion. The first was a vibration reminiscent of a diatomic molecule: the separation in time between the two solitons oscillated (as did their phases). The second was an oscillation of the phases with no change in pulse separation.

The results validate the description of interacting solitons as molecules and may also be important for future uses of soliton molecules in high-speed optical fiber communication. Two or more coupled solitons could boost transmission capacity by encoding more than one bit of information at a time, whereas isolated solitons can only encode single bits.

This research is published in Physical Review Letters.

–Matteo Rini

Matteo Rini is the Deputy Editor of Physics.


More Features »


More Announcements »

Subject Areas

OpticsNonlinear Dynamics

Previous Synopsis

Related Articles

Synopsis: Two-Face Dipole

Synopsis: Two-Face Dipole

A proposed dipole source of electromagnetic waves can selectively couple its emission into either of two neighboring waveguides. Read More »

Synopsis: X-Ray Absorption Spectroscopy on a Tabletop

Synopsis: X-Ray Absorption Spectroscopy on a Tabletop

A laser-based setup can be used to perform x-ray spectroscopy with a precision rivaling that of experiments at large-scale synchrotron facilities. Read More »

Focus: A Tiny Engine Powered by Light and Liquid Physics
Statistical Physics

Focus: A Tiny Engine Powered by Light and Liquid Physics

A micrometer-sized sphere trapped by optical tweezers in a liquid, under the right conditions, orbits rapidly around the laser beam—creating a potential micromixing device. Read More »

More Articles