Hybrid polymers processed by substrate conformal imprint lithography for the fabrication of planar Bragg gratings

Abstract

Within this work, we present an approach to use UV-enhanced substrate conformal imprint lithography (UV-SCIL) as a soft imprint technique combined with excimer laser irradiation to manufacture Bragg gratings within planar waveguides on a full wafer scale. For the first time, different hybrid polymers (OrmoComp®, OrmoStamp, OrmoCore, OrmoClad and OrmoClear) could be successfully patterned using UV-SCIL. For OrmoComp® (showing results very similar to OrmoStamp and OrmoClad) a complete imprint process could be realized. OrmoCore formed an inhibition layer in the presence of oxygen during the imprint, as could be observed for the use of OrmoClear as well. Processing options were elaborated to reduce the inhibition effect significantly, whereby the latter is mainly due to the atmospheric oxygen containing PDMS layer of the UV-SCIL working stamp. Further on, the successful realization of a planar Bragg grating operating at the telecom wavelength is demonstrated by tuning the refractive index (RI) of OrmoComp® using a phase mask and an UV excimer laser. FTIR-measurements show that the change in refractive index can be clearly correlated with a change in the chemical composition of the hybrid polymer during laser exposure