High-Q resonant modes in a quasi-three dimensional photonic crystal microcavity

A novel microcavity structure constructed in a quasi-3D photonic crystal (PhC) with a 2D PhC structure and 1D distributed Bragg reflectors (DBRs) is proposed and designed. The FDTD analysis demonstrates more than 250 times enhancement of a Purcell factor and a Q-factor compared to conventional 2D PhC slab microcavities without the cost of a mode volume. The Q-factor in the vertical direction excesses 30000 whereas that of conventional air-bridged PhC cavity is smaller than 100. Based on the Fourier-space analysis, it is pointed out that the enhancement is attributed to strong confinement of light in vertical direction by DBRs. This structure would be fabricated by means of relatively easy top-down process because it requires only one-step etching.