Photonic molecules: a new concept for wavelength tunable optical delay

The paper describes and light propagation modes in coherently coupled spherical microcavities covered with CdTe nanocrystals. We observe a rich new spectrum of resonances due to the lower symmetry of the two coupled microspheres: the photonic molecule. The quality factor Q of these new resonances are much greater than in the parent microspheres, indicating the possibility of using such coupled microcavities for the delaying of optical signals. The large number of resonances shows the possibility to have wavelength selectivity in the photonic molecule structure. In addition, we show the potential for wavelength switching with the photonic molecule structure.