Planar cavity modes in void channel polymer photonic crystals

Planar dielectric microcavities embedded in woodpile void channel photonic crystals with stop bands in the stacking direction ranging from 4.3 to 4.8 µm in wavelength were generated by femtosecond-laser direct writing in a solid polymer. Infrared transmission spectra revealed fundamental and second-order modes crossing the stop gap region with a free spectral range of 430 nm on varying the microcavity size from 0.3 to 2.25 µm. Supercell calculations confirmed the cavity size dependence of highly localized cavity modes, whereas the angle of incidence was accounted for using a simple Fabry-Perot model.