Development of high-Q photonic nanocavity using two-dimensional photonic crystal slabs

Strong confinement of light in an ultra-small cavity of optical wavelength dimensions is important for a variety of scientific and engineering fields. Ultra-small and high-resolution filters, biosensors, low-threshold nanolasers, single-photon emitters for quantum communications, optical memories, photonic chips, etc. can be realized using a high-Q photonic nanocavity in which strong light-matter interactions occur. However, such a cavity is difficult to construct because radiation loss increases in inverse proportion to size of the cavity. Kyoto University and Sumitomo Electric have found an important design rule that light should be confined gently (like a perfect gaussian curve) in order to obtain high-Q factor while maintaining a very small modal volume V. According to this rule, the authors have succeeded in realizing a photonic cavity with both high 0 and very small modal volume V, using a two-dimensional photonic crystal slab. The value of Q / V, which is a figure of merit of photonic nanocavity, is larger than that of any other cavities ever reported in previous works.