Combined nano-imprint and photolithography (CNP) of integrated polymer optics

We demonstrate wafer-scale fabrication of integrated polymer optics, comprising nm to mm features, by combined nanoimprint and photolithography (CNP). Active and passive polymer optical components are integrated: Distributed feed-back (DFB) polymer dye lasers and polymer waveguides. The laser devices are defined in SU-8 resist, doped with Rhodamine 6G laser dye, shaped as planar slab waveguides on a Si/SiO2 substrate, and with a Ist-order DFB surface corrugation forming the laser resonator.

In the CNP process, a combined UV mask and nanoimprint stamp is embossed into the resist, which is softened by heating, and UV exposed. Hereby the mm to /mi sized features are defined by the UV exposure through the metal mask, while nm-scale features are formed by mechanical deformation (nanoimprinting).

The UV exposed (and imprinted) SU-8 is crosslinked by a post-exposure bake, before the stamp and substrate are separated, and the un-exposed resist is dissolved. Polymer waveguides are added to the system by an additional UV lithography step in a film of un-doped SU-8, which is spincoated on top of the lasers and substrate.

When optically pumped at 532 nm, lasing is obtained in the wavelength range 559 nm - 600 nm, determined by the grating period. Our results, where 20 laser devices are defined across a 10 cm diameter wafer substrate, demonstrate the feasibility of CNP for wafer-scale fabrication of advanced nano-structured active and passive polymer optical components.