We demonstrate a novel SOI-based photonic crystal(PC) double-heterostructure slot waveguide microcavity constructed by cascading three PC slot waveguides with different slot widths,and simulate the luminescence enhancement of sol-gel Er-doped SiO2 filled in the microcavity by finite-difference time-domain(FDTD) method.The calculated results indicate that a unique sharp resonant peak dominates in the spectrum at the expected telecommunication wavelength of 1.5509 mm,with very high normalized peak...