Surface exciton polaritons supported by a J-aggregate-dye/air interface at room temperature.

Surface exciton polaritons (SEPs) are very important for the realization of novel sensors and next-generation optical devices. Here we propose for the first time, to the best of our knowledge, a Kretschmann-Raether device that is able to induce SEPs propagating along the interface between a J-aggregate cyanine dye and air at room temperature. This configuration has the advantages of being straightforward to realize and easy to study because the Kretschmann-Raether approach is the most simple and fundamental from the theoretical point of view. Here a J-aggregate cyanine dye produces strong binding energy due to Frenkel excitons, and this enables the observation of SEPs easily at room temperature. One of the advantages of the use of the J-aggregate cyanine dye is the simple device preparation. This is because the J-aggregate cyanine dye can be easily deposited on any arbitrary substrates with a spincoating or dip-coating technique from its aqueous solution in ambient condition. We observed SEPs at room temperature, and the deepest resonant peak was obtained for a 94 nm thick 5,6-dichloro-2-[[5,6-dichloro-1-ethyl-3-(4-sulfobutyl)-benzimidazol-2-ylidene]-propenyl]-1-ethyl-3-(4-sulfobutyl)-benzimidazolium hydroxide film at 532 nm wavelength. Our results may pave the way for the realization of novel SEP biosensors in a simple and straightforward way at room temperature.