Narrow-band transmission filter based on 1D-PCs with a defect layer

A narrow-band transmission filter based on one-dimensional photonic crystals with SiO₂/titaniumdioxide(TiO₂) layers is grown by sol-gel spin-coating processing. The structural and optical properties of fabricated samples are characterized by an atomic force microscope, scanning electron microscope, and UV-visible spectroscopy. Specific wavelength transmission and bandgap in the optical filter with and without a defect layer have been investigated by engineering the layer thickness and defect layer material. For three fabricated optical filters, it is found that the maximum transmission for the TiO₂ and InP defect layers reaches 58.09% and 42.21%, respectively. The layer thickness is fixed just by tuning the rotational speed of the spin-coater.