Direct observation of complex dynamics in optical cavities.

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• Prof. Stephen Creagh, University of Nottingham
• Thursday 21 November 2013, 13:45-15:00
• Theory Library.

If you have a question about this talk, please contact Kevin Ralley.

Strongly directional emission may be achieved from whispering gallery modes in optical resonators which are only very slightly deformed from spherical or circular geometry. The ability to effect dramatic changes in the external field using very small geometry changes is potentially useful in applications such as lasers, sensors and filters, but an analytical description of this phenomenon is surprisingly challenging. A natural theoretical approach is to use short-wavelength approximations to treat the evanescent, external field, but the the required complex ray data is often not defined.

We exploit an approach which circumvents this problem by constructing approximate solutions of the eikonal equation for ray families which permit extension as far as required into the complex domain. The method successfully predicts the strong directionality seen in very weakly deformed resonators. An especially interesting regime occurs when the underlying ray family satisfies resonant conditions which put it near an island chain in the ray-dynamical phase space. Here one finds that the external and internal fields can differ in stark, counterintuitive ways. An explanation of this effect involves ideas of resonance-assisted tunnelling previously developed in the quantum context.

This talk is part of the Theoretical Physics Seminars series.

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