Carl A. Morse Professor of Applied Physics and Physics Yale University
报告时间:
2008-03-24 16:30
报告地点:
物理系三楼报告厅
主办单位:
物理系
简介:
摘要： 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 microcavity 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 microdisk and deformed disk lasers, and two-dimensional random lasers. The random laser in the diffusive regime has no measurable linear resonances at all, despite it 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.
