light bullet
Light bullets are localized pulses of electromagnetic energy that can travel through a medium and retain their spatiotemporal shape in spite of diffraction and dispersion which tend to spread the pulse. This is made possible by a balance between the non-linear self-focusing and spreading effects brought about by the medium in which the pulse beam propagates.{{cite journal|title=Viewpoint: Generation of light bullets|url=http://physics.aps.org/articles/v3/107}}
Prediction and Discovery
Light bullets were predicted and so termed by Yaron Silberberg in 1990,{{Cite journal|last=Silberberg|first=Yaron|date=1990-11-15|title=Collapse of optical pulses|journal=Optics Letters|language=EN|volume=15|issue=22|pages=1282–4|doi=10.1364/OL.15.001282|pmid=19771066|issn=1539-4794|bibcode=1990OptL...15.1282S}} and demonstrated the following decade.
Comparison with solitons
Spatial and temporal stability which are the characteristics of a soliton have been achieved in light bullets using alternative refractive index models. An experiment which exploited the discrete spreading and self-focusing effects on 170-femtosecond pulses at 1550-nanometre wavelengths by a two-dimensional hexagonal array of silica waveguides reported a spatial profiles stationary for about twice as far as it would be in linear propagation and temporal profile about nine times stationary as that of the corresponding linear propagation.{{cite journal|title=Viewpoint: Generation of light bullets|url=http://physics.aps.org/articles/v3/107}}
Light bullets lose energy in the process of a collision. This behavior is different from that of solitons which survive collisions without losing energy{{cite web|title=Light bullets|url=https://www.sfu.ca/~renns/lbullets.html}}
Possible applications
- Artificially-induced lightning{{cite web|title=Laser Triggers Lightning "Precursors" in Clouds|url=http://news.nationalgeographic.com/news/2008/04/080416-lightning-lasers_2.html|archive-url=https://web.archive.org/web/20080709062628/http://news.nationalgeographic.com/news/2008/04/080416-lightning-lasers_2.html|url-status=dead|archive-date=July 9, 2008}}
- Monitoring air pollution{{cite web|title=Laser "Light Bullets" Made to Curve|url=http://news.nationalgeographic.com/news/2009/04/090409-light-bullets-curve.html|archive-url=https://web.archive.org/web/20090717005545/http://news.nationalgeographic.com/news/2009/04/090409-light-bullets-curve.html|url-status=dead|archive-date=July 17, 2009}}