Picosecond and low-power all-optical switching based on an organic photonic-bandgap microcavity

Photonic crystals, materials with periodic dielectric structures, are able to control the propagation states of photons owing to the so- called photonic- bandgap effect(1). Nonlinear photonic crystals, whose refractive- index distribution can be tuned optically, have been used to demonstrate all- optical switching(2). However, a high pump intensity is usually required because the nonlinear optical coefficient of conventional materials is relatively small(3). Here we report ultrafast and low- power photonic- crystal all- optical switching based on strong optical nonlinearity enhancement due to excited- state interelectron transfer. Compared with the case without nonlinearity enhancement, the switching operation power is reduced by four orders of magnitude while the ultrafast response time, of the order of a picosecond, is maintained. This provides a strategy for constructing photonic materials with large nonlinearity and studying ultrafast low- power integrated photonic devices.