Enhanced sensing in mixed porous–solid photonic stacks

A mix-and-match sol–gel deposition method allows fabrication of one-dimensional photonic bandgap materials with strategically placed porous layers. Examples of fabricated optical devices include a Bragg mirror with an ultra-high refractive index difference, an all-silica optical reflection switch and a porous Fabry–Perot microcavity with excellent relative humidity sensing ability.