SoylentNews

RandomFactor [soylentnews.org] writes:

Spanish and American researchers from several organizations have announced the discovery of a new property of light [phys.org] - Self-Torque.

Researchers were working with multiple laser beams exhibiting twisting or Orbital Angular Momentum (OAM) which they fired into a cloud of Argon gas forcing them to overlap.

[the beams] joined and were emitted as a single beam from the other side of the argon cloud. The result was a type of vortex beam. The researchers then wondered what would happen if the lasers had different orbital angular momentum and if they were slightly out of sync. This resulted in a beam that looked like a corkscrew with a gradually changing twist. And when the beam struck a flat surface, it looked like a crescent moon. The researchers noted that looked at another way, a single photon at the front of the beam was orbiting around its center more slowly than a photon at the back of the beam. The researchers promptly dubbed the new property self-torque—and not only is it a newly discovered property of light, it is also one that has never even been predicted.

The researchers indicate this behavior might be used to modulate the OAM of light similar to how frequencies are modulated in communications equipment, the journal article concludes that

because the OAM value is changing on femtosecond time scales, at wavelengths much shorter than those of visible light, self-torqued [high harmonic generation (HHG)] beams can be extraordinary tools for laser-matter manipulation on attosecond time and nanometer spatial scales.

Useful if you want to engrave 9906947-XB71 on your work.

Journal Reference
Laura Rego et al. Generation of extreme-ultraviolet beams with time-varying orbital angular momentum, Science (2019). DOI: 10.1126/science.aaw9486 [sciencemag.org]

Original Submission