Multimode Dynamics in Ring Lasers

Ring Lasers show very different dynamical behaviours due to
their many degrees of freedom, their
symmetry properties and high non linear medium. Reported dynamics
range from limit cycle oscillations, to
mode-locking, bi-stability in propagation direction, etc...
The work here presented is focused on the spatio temporal dynamical
behaviour of the electric fields
retaining the spatial effects induced to the medium.

In the first part of the talk, the longitudinal modal properties of a
Ring cavity are studied and
compared with the modal properties of a Fabry-Pérot cavity and
applied experiments onto the modal properties
of a real device, in this case a Semiconductor Ring Laser with
light extraction sections
[S.Fürst, et al. Appl. Phys. Lett. 93, 251109 (2008)].

In the second part of the talk, the multimode dynamics of a two-level
ring laser is numerically explored
using a bidirectional Travelling Wave Model retaining the spatial
effects due to the
presence of counter-propagating electric fields in the population
inversion. Novel dynamical
regimes where the emission in each direction occurs at different
wavelength are studied. Modelocked
unidirectional emission for large gain bandwidth and relatively small
detuning is reported.
Finally, I will discuss about other optical cavities geometries.