Princeton University

School of Engineering & Applied Science

Ab Initio Laser Theory and Coherent Enhancement of Absorption

Speaker: 
A. Douglas Stone, Yale University
Location: 
Engineering Quadrangle B205
Date/Time: 
Friday, March 14, 2014 - 2:00pm to 3:00pm

<strong>Abstract:</strong> This talk consists of two distinct but related topics. The first part outlines Steady-state ab initio laser theory (SALT), a recently developed method for finding the steady-state solutions of the semiclassical laser equations directly without integrating them in time. The method approaches lasers as kind of non-hermitian scattering problem and is well-suited to deal with complex modern laser systems such as micro and nano lasers, photonic crystal and random lasers. The theory treats the openness of the cavity exactly and the non-linear modal interactions to infinite order; and has been shown to be very accurate for N-level lasers, even for multimode lasing high above threshold, in a large parameter regime.  Two efficient techniques for solving these equations are briefly reviewed. The laser linewidth, a quantum property of the laser, can also be calculated via SALT based methods, leading to a general formula for the linewidth which contains all known corrections to the Schawlow-Townes formula (e.g. Petermann, Henry alpha) in limiting cases.
 
 The second part of the talk was motivated by the time-reversal properties of the laser equations at threshold, which imply the possibility of coherent perfect absorption of the time-reverse of the lasing mode (but not of other input fields). This leads to the more general concept of coherent enhancement of absorption in multiple scattering media.  I will briefly explain these concepts and present recent unpublished experimental results demonstrating this and the related effect of coherently enhanced transmission through opaque media.
 
<strong>Biography:</strong> A. Douglas Stone is Carl A. Morse Professor and Chair of Applied Physics, and Professor of Physics at Yale University. He joined the Yale faculty in 1986, was promoted to Professor in 1990 and previously has served terms a Chair of Applied Physics and Director of the Division of Physical Sciences.  Before coming to Yale he obtained a Master's degree in Physics and Philosophy from Oxford in 1978 (where he was a Rhode's Scholar), a PhD in 1983 in theoretical condensed matter physics from MIT under the supervision of John Joannopoulos, and did postdoctoral work at IBM’s Yorktown Heights Laboratory (1983-5).
 
 His PhD work was in condensed matter theory and the early part of his career focused on problems in mesoscopic electron systems and quantum fluctuations.  His ground breaking work with Patrick Lee on universal conductance fluctuations is one of the most cited works in all of physics from the 1980's (~ 2300 ISI citations) and was recognized by the McMillan Award of the University of Illinois at Urbana for “outstanding contributions to condensed matter physics”.  For the past decade he has focused his research on optics, and specifically on microcavity optics and laser physics, and holds four patents in these areas.  His group proposed the asymmetric resonant cavity laser in 1997 based on chaotic ray dynamics, has developed since 2005 Steady-state Ab initio Laser Theory (SALT), and in 2010 proposed the concept of time-reversed lasing or coherent perfect absorption. He was elected a Fellow of the Optical Society of America in 2010 for his work in laser physics and is also a Fellow of the American Physical Society and an honorary member of the Aspen Center for Physics. In 2013 he published a popular science book with Princeton University Press, Einstein and the Quantum: The Quest of the Valiant Swabian.