[Phys-seminars] 2017-05-04 Lasers Seminar

barmash barmash at bgu.ac.il
Sat Apr 29 17:43:19 IDT 2017

Lasers Seminar

 DATE: 04-05-17

 TIME: 15:30

 PLACE: Physics building (#54) room 207

Exact eigenmode formulation for wave propagation in open/lossy systems

Parry Yu Chen, The Unit of Electro-Optical Engineering, Ben-Gurion University

Wave propagation in open and/or lossy resonators is increasingly topical, for example in optics, due to the prevalence of nanoplasmonic resonators that lose energy due to both radiation and material losses. Normal-mode or eigenmode expansion is a highly efficient method of calculating the scattering of fields generated by any configuration of point, bulk, or far-field sources without repeated simulation. However, loss and open boundaries present many challenges for eigenmode methods. This is true also of quantum scattering problems, or any system described by a wave equation. We present a simple, practical formulation that overcomes all complexities and deficiencies of previous approaches. Specifically, our eigenmodes are obtained from a linear eigenvalue equation, and do not exhibit non-physical far- field divergence. The modes are complete, with a discrete set capable of replacing a continuous set of radiation modes. In most cases, few modes are necessary, facilitating both
  analytic calculations and unified insight. Our method yields the Green’s function and its variation over source and detector positions and orientations. This is a fundamental electrodynamics quantity, encapsulating the electromagnetic density of states. In particular, we consider nanoplasmonic systems, as these can enhance light-matter interaction, and thus spontaneous emission rates, by many orders of magnitude. This has enabled spectroscopy of single molecules, engineering of black-body radiation for energy harvesting, and potentially generating single photons for quantum computing. Further applications include Förster energy transfer, quantum friction, and optical forces. However, enhancements are highly sensitive to the position and orientation of quantum emitters relative to the nanoparticle. Thus, the number of numerical simulations required to fully characterize nanoplasmonic geometries can be prohibitive, motivating our eigenmode approach.

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