oscillating domains

The existence of stable directional domains in a ring laser has been suggested in several theoretical papers. Such domains would be very interesting to control since some numerical predictions indicated that they could be controlled independently of each other and therefore have properties analogous to those of transverse cavity solitons. Those domains would therefore be a kind of transverse localized structure based on directional bistability.

A couple of years ago we set out to explore that in a specially crafted semiconductor ring laser. We have discussed the purely temporal dynamics of this system in an earlier paper about mode-locking in ring semiconductor laser: Instead of pure directional bistability we have observed a mode-locked emission with anticorrelated dynamics in each emission direction.

Essentially we have interpreted these observations in terms of alternate oscillations in a strongly multimode device. This observation was however conditioned by the presence of some mechanism (in this case a simple pinhole) forcing the competition between the two emission directions. When this condition is relaxed, more complex effects can take place since both emission directions do not necessarily share the same active medium if directional segregation takes place.

In this new paper, we have analyzed the behavior of the system without constraining the transverse degrees of freedom. We have also taken to opportunity to present an unusual level of modelling aiming at accurately describing the interface between waves propagating in each direction. We did not observe the stable directional domains that we were hoping for but still Alessio measured an interesting phenomenon: directional segregation appears to take place, but coupling between both emission directions make the domains oscillatory. The paper is now online, to be published in the special issue of the IEEE Journal of selected topics in Quantum Electronics about semiconductor lasers.

The paper is on our publications page: it is about oscillating directional domains in semiconductor ring laser.