SiO 2 / TiO 2 omnidirectional reflector and microcavity resonator via the sol-gel method

Thin films of ${\mathrm{SiO}}_{\mathrm{2}}$ and ${\mathrm{TiO}}_{\mathrm{2}}$ were used to fabricate one-dimensional photonic crystal devices using the sol-gel method: an omnidirectional reflector and microcavity resonator. The reflector consisted of six ${\mathrm{SiO}}_{\mathrm{2}}{\mathrm{/TiO}}_{\mathrm{2}}$ bilayers, designed with a stopband in the near infrared. Reflectivity over an incident angle range of 0°–80° showed an omnidirectional band of 70 nm, which agrees with theoretical predictions for this materials system. The microcavity resonator consisted of a ${\mathrm{TiO}}_{\mathrm{2}}$ Fabry–Perot cavity sandwiched between two ${\mathrm{SiO}}_{\mathrm{2}}/{\mathrm{TiO}}_{\mathrm{2}}$ mirrors of three bilayers each. We have fabricated a microcavity with resonance at λ=1500 nm and achieved a quality factor of $\text{Q=35.}$ We measured a resonance frequency modulation with a change in incident angle of light and defect layer thickness.