Abstract
In this work, we describe a scheme to execute all-optical control of the routing or switching of photonic information where, by optically controlling the internal quantum state of a individual scatterer coupled to two independent cavity modes, one can dynamically and rapidly modulate the intermode coupling. This allows all-optical modulation of intercavity couplings via ac Stark or shuffle (stimulated Raman adiabatic passage) control of the scatterer’s internal states, and from this modulation, we show that we can perform all-optical switching and all-optical routing with near-unit switching contrast and with high bandwidth.
- Received 26 November 2012
DOI:https://doi.org/10.1103/PhysRevX.3.031013
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Published by the American Physical Society
Popular Summary
One of the paradigmatic material platforms for both classical optical communication and quantum information processing is a network of photonic emitters, optical cavities, and photonic waveguides connecting the emitters and cavities. Switching photon transmission on or off and routing photons into different paths in such a network are obviously vital operations, which require a high degree of control, high switching contrast, and low photon loss in routing. In this paper, we present a theoretical proposal that achieves these goals with all-optical means, i.e., by dynamic control of the interactions between photonic modes in different optical cavities.
The general concept of all-optical routing and switching of photons is not new and has indeed been experimentally realized. For switching, the existing all-optical methods tune the on-off resonance of cavities along the transmission paths either by laser-induced weak optical nonlinearity or by slowly moving a photon scatterer in the network, or by adjusting the spatial gap between cavities. Their drawbacks are the requirement of intense lasers, low switching contrast, or low switching speed. Routing is done by a scatterer coupled to the waveguide, which allows for either forward or backward routing only and suffers high photon loss when used in multiport routers.
As a fundamental departure, our proposal uses a three-level atomic scatterer placed within or nearby a cavity to control the coupling between the cavity and its neighboring cavity. Through its atomic transition between the lowest and the highest levels, the scatterer interacts with two photonic modes of the same frequency, one from each of the two cavities, leading to an effective coupling between the two cavities. Therefore, by manipulating the internal states of the atom using a classical optical field, the effective coupling can be turned on and off quickly, thus switching on and off the photon transmission with near completeness. Based on this basic mechanism, a low-loss router can then also be built by coupling the upstream cavity to individual downstream cavities through different scatterers that can be optically manipulated independently.
Our proposal applies to solid-state emitter and cavity systems like quantum dots or nitrogen-vacancy centers in nanodiamonds and should enable on-chip integration of the switching and routing components. Single-photon routing and generation of coherent photons entangled to a single coherent input field should also be potential expansions of this proposal.