"Ab Initio" Theory of Novel Micro and Nanolasers
19 May 2008 | Online Presentations | Contributor(s): A. Douglas Stone
While the laser is one of the most important inventions of the past century and one of the most interesting and controllable non-linear systems in physics, there is surprisingly little predictive theory of lasing properties. Predicting lasing thresholds and output power far above threshold in the case of multiple interacting lasing modes
presents a serious challenge to current theory. Many new laser designs have emerged as a consequence of modern micro and nanofabrication capabilities, for example micro cavity lasers, random lasers and photonic crystal lasers, and an improved analytic theory of lasing is necessary to understand and predict their properties.
In this talk, I will sketch such a theory, which describes the open (non-hermitian) nature of a laser exactly in terms of
biorthogonal modes, and treats the non-linear interactions to all orders. Thus, the theory can predict lasing properties quantitatively from knowledge of the dielectric function of the resonator and from basic properties of the
gain medium, yielding an "ab initio" method to determine lasing states. The theory will be illustrated by application to one-dimensional edge-emitting lasers, two-dimensional micro disk and deformed disk lasers, and two-dimensional random lasers. The random laser in the diffusive regime has no measurable linear resonances at all,
despite its sharp lasing lines in the presence of gain. Thus, its description is beyond the reach of conventional
laser theory and the nature of its lasing modes was previously unknown.