Light bullet

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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. [1]

Contents

Prediction and Discovery

Light bullets were predicted and so termed by Yaron Silberberg in 1990, [2] 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. [3]

Light bullets lose energy in the process of a collision. This behavior is different from that of solitons which survive collisions without losing energy [4]

Possible applications

See also

Related Research Articles

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Nonlinear optics

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Photoionization mode

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Self-focusing

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Optical rogue waves

Optical rogue waves are rare pulses of light analogous to rogue or freak ocean waves. The term optical rogue waves was coined to describe rare pulses of broadband light arising during the process of supercontinuum generation—a noise-sensitive nonlinear process in which extremely broadband radiation is generated from a narrowband input waveform—in nonlinear optical fiber. In this context, optical rogue waves are characterized by an anomalous surplus in energy at particular wavelengths and/or an unexpected peak power. These anomalous events have been shown to follow heavy-tailed statistics, also known as L-shaped statistics, fat-tailed statistics, or extreme-value statistics. These probability distributions are characterized by long tails: large outliers occur rarely, yet much more frequently than expected from Gaussian statistics and intuition. Such distributions also describe the probabilities of freak ocean waves and various phenomena in both the man-made and natural worlds. Despite their infrequency, rare events wield significant influence in many systems. Aside from the statistical similarities, light waves traveling in optical fibers are known to obey the similar mathematics as water waves traveling in the open ocean, supporting the analogy between oceanic rogue waves and their optical counterparts. More generally, research has exposed a number of different analogies between extreme events in optics and hydrodynamic systems. A key practical difference is that most optical experiments can be done with a table-top apparatus, offer a high degree of experimental control, and allow data to be acquired extremely rapidly. Consequently, optical rogue waves are attractive for experimental and theoretical research and have become a highly studied phenomenon. The particulars of the analogy between extreme waves in optics and hydrodynamics may vary depending on the context, but the existence of rare events and extreme statistics in wave-related phenomena are common ground.

Luigi Lugiato

Luigi Lugiato is an Italian physicist and professor emeritus at University of Insubria (Varese/Como). He is best known for his work in theoretical nonlinear and quantum optics, and especially for the Lugiato–Lefever equation (LLE,). He has authored more than 340 scientific articles, and the textbook Nonlinear Dynamical Systems. His work has been theoretical but has stimulated a large number of important experiments in the world. It is also characterized by the fact of combining the classical and quantum aspects of optical systems.

Wide-field multiphoton microscopy refers to an optical non-linear imaging technique tailored for ultrafast imaging in which a large area of the object is illuminated and imaged without the need for scanning. High intensities are required to induce non-linear optical processes such as two-photon fluorescence or second harmonic generation. In scanning multiphoton microscopes the high intensities are achieved by tightly focusing the light, and the image is obtained by beam scanning. In wide-field multiphoton microscopy the high intensities are best achieved using an optically amplified pulsed laser source to attain a large field of view (~100 µm). The image in this case is obtained as a single frame with a CCD without the need of scanning, making the technique particularly useful to visualize dynamic processes simultaneously across the object of interest. With wide-field multiphoton microscopy the frame rate can be increased up to a 1000-fold compared to multiphoton scanning microscopy. Wide-field multiphoton microscopes are not yet commercially available, but working prototypes exist in several optics laboratories.

The model usually designated as Lugiato–Lefever equation (LLE) was formulated in 1987 by Luigi Lugiato and Renè Lefever as a paradigm for spontaneous pattern formation in nonlinear optical systems. The patterns originate from the interaction of a coherent field, that is injected into a resonant optical cavity, with a Kerr medium that fills the cavity.

References

  1. "Viewpoint: Generation of light bullets".Cite journal requires |journal= (help)
  2. Silberberg, Yaron (1990-11-15). "Collapse of optical pulses". Optics Letters. 15 (22): 1282–4. Bibcode:1990OptL...15.1282S. doi:10.1364/OL.15.001282. ISSN   1539-4794. PMID   19771066.
  3. "Viewpoint: Generation of light bullets".Cite journal requires |journal= (help)
  4. "Light bullets".
  5. "Laser Triggers Lightning "Precursors" in Clouds".
  6. "Laser "Light Bullets" Made to Curve".