Optical cavity based on porous silicon superlattice technology

It is demonstrated that luminescent porous silicon (PS) is applicable to a vertical optical cavity which operates at wavelengths in the visible region. The PS device consists of a high-reflectivity thin Ag film, a light-emitting PS layer, and a quarter-wavelength multilayer reflector fabricated by precisely controlled PS superlattice (PSSL) technology. The reflectivity of a prepared PSSL mirror is higher than 90% at designed wavelengths. When excited by a UV laser, the device acts as a Fabry-Perot resonator. Based on experimental studies of emission spectra as a function of major design parameters (the number of PSSL pairs and the cavity length), the linewidth is significantly decreased to 6 meV in full width at half-maximum. The change in the linewidth with the cavity length is consistent with the behavior expected from a simplified theoretical analysis. These results confirm that PS is applicable for silicon-based photonic devices.