Total photon absorption

Vivek Venkataraman, Kasturi Saha, Pablo Londero +1 more

We show 20% all-optical modulation with less than 2 nW total power via non-degenerate two-photon absorption in Rb vapor confined to a photonic bandgap fiber. This corresponds to about 15 photons of switching energy.

Anton N. Vetlugin, Ruixiang Guo, Angelos Xomalis +4 more

Large distance implementation of quantum communication technologies requires coherent control of single photons in optical fiber networks. Here we demonstrate the phenomenon of coherent perfect absorption of single photons in a fully fiberized ultrathin plasmonic metamaterial fabricated at the end facet of an optical fiber. Continuous control of single-photon absorption probability is achieved by driving the network between the regimes of coherent total absorption and coherent total transmission. To circumvent phase fluctuations inherent to optical fiber networks, we implemented a reference-based postselection technique which yielded interference fringe visibility comparable to that of free space experiments. Coherent absorption of quantum light in fiber environment provides new opportunities for dissipative single-photon switching, filtering, and measurement, as well as for manipulation of entangled, weak coherent, and NOON states in optical fiber networks.

Horia I. Metiu

Kasturi Saha, Vivek Venkataraman, Pablo Londero +1 more

We show that two-photon absorption (TPA) in rubidium atoms can be greatly enhanced by the use of a hollow-core photonic-band-gap fiber. We investigate off-resonant, degenerate Doppler-free TPA on the $5{S}_{1/2}\ensuremath{\rightarrow}5{D}_{5/2}$ transition and observe $1%$ absorption of a pump beam with a total power of only 1 mW in the fiber. These results are verified by measuring the amount of emitted blue fluorescence and are consistent with the theoretical predictions which indicate that transit-time effects play an important role in determining the two-photon absorption cross section in a confined geometry.

Stephen V. Kershaw