Two-step photolithographic technique for laterally coupled hybrid polymer microring resonators

We propose a simple and fast two-step patterning technique that allows controlling the gap between rings and port waveguides in lateral couplers, as well as independently adjusting the height of the different waveguides. Despite the proximity mode exposure, inducing a strong diffraction of the UV light at the apertures on the mask, the patterning technique resulted very precise, with 0.30 mum wide gaps between the ports and the ring.