Modified spontaneous emission from erbium-doped photonic layer-by-layer crystals

The spontaneous emission from luminescent Si photonic layer-by-layer crystals is studied. Luminescence from both implanted Er ions and the polycrystalline Si host is observed in the 1.1–1.7 $\mu \mathrm{m}$ wavelength range and serves as a probe of the photonic band structure. The spontaneous emission is strongly suppressed for wavelengths between 1.4 and 1.7 $\mu \mathrm{m}.$ The spectral changes are described by a model that takes into account changes in the local density of states, internal Bragg scattering in the crystal, and the internal quantum efficiency of the optical transition involved. A spectral attenuation of $\sim 5\mathrm{dB}$ per unit cell is derived from the spontaneous emission data, consistent with theory and transmission data.