Confinement and optimization of electromagnetic wave in photonic crystals based on SU-8 photoresist strip

Abstract

Confinement of electromagnetic wave is key to the realization of applicable filters in optics technologies. We present a flexible cavity fabrication process that writes SU-8 photoresist microstrip onto a photonic crystal waveguide deterministically, in which electromagnetic wave can be confined excellently. Corresponding simulation shows bandgap of the waveguide shifts from 0.269c/a to 0.266c/a by adding a 0.1µm-thick layer of SU-8 with a refractive index of 1.57 on top of PhC. This is equivalent to an increment in wavelength from 1.265 µm to 1.277 µm. We also study the relationship of the Q factor with the strip width of SU-8 strip cavity. Tesults show that as the strip width is increased beyond 2 µm, Q_total increases by up to approximately an order of magnitude, while V₀ increases by only a factor of 2. It provides a way to optimize Q factor and hence enables potential improvement on optical cavity mode.