The strange world of self-induced transparency and light bullets

The passage of very bright, very short light pulses through an optical material shows many interesting and useful effects. Normally, the pulse would spread out in space and time as a result of diffraction and dispersion. However when the pulse is very bright, nonlinear effects can exactly cancel this spreading, and the light pulse propagates without any change in shape: a 'soliton' or 'light bullet'. It is easier to form solitons when the light is confined to a small cavity, and 'cavity solitons' are now attracting interest as a way of storing and manipulating data for optical storage or optical computing. Another effect, seen when the pulse duration is very short, is self-induced transparency (SIT), in which the material which normally absorbs light becomes completely transparent to a bright, short-duration light pulse.

This research project is based on theoretical predictions by one of the co-investigators, Dr. Gabriella Slavcheva. Using a new theory of nonlinear coherent pulse dynamics based on Richard Feynman's model of atoms in an electromagnetic field, Dr. Slavcheva predicted the existence of cavity solitons formed as a result of self-induced transparency.

With the help of collaborators from the École Normale Supérieure in Paris, and the University of Arizona, the scientists from the ATI will employ both theory and experiment to demonstrate the existence of this new type of soliton and to investigate the potential for applications in information technology and communications.

“Soliton Formation through Self-Induced Transparency in Semiconductor Microcavities”, Professor Ortwin Hess, Professor Jeremy Allam & Dr. Gabriela Slavcheva (EPSRC grant EP/D060958/1)