Abstract
In a recent work, Y. D. Chong et al. [Phys. Rev. Lett. 105, 053901 (2010)] proposed the idea of a coherent perfect absorber (CPA) as the time-reversed counterpart of a laser, in which a purely incoming radiation pattern is completely absorbed by a lossy medium. The optical medium that realizes CPA is obtained by reversing the gain with absorption, and thus it generally differs from the lasing medium. Here it is shown that a laser with an optical medium that satisfies the parity-time symmetry condition for the dielectric constant behaves simultaneously as a laser oscillator (i.e., it can emit outgoing coherent waves) and as a CPA (i.e., it can fully absorb incoming coherent waves with appropriate amplitudes and phases). Such a device can thus be referred to as a -symmetric CPA laser. The general amplification or absorption features of the CPA laser below lasing threshold driven by two fields are determined.
- Received 26 July 2010
DOI:https://doi.org/10.1103/PhysRevA.82.031801
©2010 American Physical Society
Synopsis
Absorbing lasers
Published 27 September 2010
Symmetry arguments reveal the necessary conditions for building a device that can act as both a perfect emitter and a perfect absorber.
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