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arXiv:1001.1000 · Physical Review A

Optical analog of population trapping in the continuum: Classical and quantum interference effects

Stefano Longhi

Published Feb 9, 2009• 38 citations
arXivHTMLPDF

Abstract

A quantum theory of light propagation in two optical channel waveguides tunneling coupled to a common continuum of modes (such as those of a slab waveguide) is presented, and classical and quantum interference effects are investigated. For classical light, the photonic system realizes an optical analog of coherent population trapping in the continuum encountered in atomic physics, where destructive interference between different light leakage channels leads to the appearance of a trapped state embedded in the continuum. For nonclassical light, two-photon interference effects are predicted, such as the tendency of photon pairs to bunch when decaying into the continuum.

DOI
10.1103/physreva.79.023811

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A quantum theory of light propagation in two optical channel waveguides tunneling coupled to a common continuum of modes (such as those of a slab waveguide) is presented, and classical and quantum interference effects are investigated. For classical light, the photonic system realizes an optical analog of coherent population trapping in the continuum encountered in atomic physics, where destructive interference between different light leakage channels leads to the appearance of a trapped state embedded in the continuum. For nonclassical light, two-photon interference effects are predicted, such as the tendency of photon pairs to bunch when decaying into the continuum.
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A semiclassical model consisting of two noninteracting waveguide arrays along with three side-coupled waveguides is presented to demonstrate the optical analogue of double Fano resonance. The photonic system is configured so that it causes simultaneous cross coupling between two decay channels via one array and another two decay channels via the other array. Owing to the two individual interference effects, the decay-rate profile for the waveguide coupled directly to the continuum exhibits two asymmetric peaks, or dips, or a combination of one peak and one dip in the vicinity of the frequency mismatches. As far as the distribution of optical field amplitudes in the side-coupled waveguides is concerned, the present model also demonstrates the features of optical trapping (optical analogue of coherent population trapping) in side-coupled waveguides under certain symmetric parametric conditions.
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