General theory of spontaneous emission near exceptional points
We present a general theory of spontaneous emission at exceptional points (EPs)- exotic degeneracies in non-Hermitian systems. Our theory extends beyond spontaneous emission to any light-matter interaction described by the local density of states (e.g., absorption, thermal emission, and nonlinear fr...
| Main Authors: | , , , , , , , |
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| Other Authors: | |
| Format: | Article |
| Published: |
The Optical Society
2018
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| Online Access: | http://hdl.handle.net/1721.1/115585 https://orcid.org/0000-0002-7572-4594 https://orcid.org/0000-0002-7184-5831 https://orcid.org/0000-0001-7327-4967 |
| Summary: | We present a general theory of spontaneous emission at exceptional points (EPs)- exotic degeneracies in non-Hermitian systems. Our theory extends beyond spontaneous emission to any light-matter interaction described by the local density of states (e.g., absorption, thermal emission, and nonlinear frequency conversion). Whereas traditional spontaneous-emission theories imply infinite enhancement factors at EPs, we derive finite bounds on the enhancement, proving maximum enhancement of 4 in passive systems with second-order EPs and significantly larger enhancements (exceeding 400×) in gain-aided and higher-order EP systems. In contrast to non-degenerate resonances, which are typically associated with Lorentzian emission curves in systems with low losses, EPs are associated with non-Lorentzian lineshapes, leading to enhancements that scale nonlinearly with the resonance quality factor. Our theory can be applied to dispersive media, with proper normalization of the resonant modes. |
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