Fabrication and optimization of su-8 microring resonators

In the present work an optimization study on the performances of polymeric ring resonator is reported. An embedded structure, characterized by the presence of an under and upper layer of Su-8 2002, is chosen in order to improve the optical performances, in terms of quality factor and extinction ratio. Specific combinations of Su-8 2002 diluted in cyclopentanone are tested as under-layer in single mode ring resonators. Morphological analysis indicated that the employment of Su-8 with 3% solid content increases the quality factor of about 20% respect to the standard structure. Moreover, the employment of a spin-coated Su-8 upper-layer increases the optical performances of about 50% due to a reduction of the surface roughness, intrinsic of photolithographic process.