Waveguide fabrication using proton beam writing

Abstract

Proton beam writing (P-beam writing) is an emerging direct-write lithographic technique that is being developed at the Centre for Ion Beam Applications (CIBA). Evolved from nuclear microscopy techniques less than a decade ago, it now boasts a wide spectrum of possible niche application areas, ranging from micro/nano-lithography; micro/nano-photonics; micro/nano-fludics; micro/nano-stamp technology, etc. One of its greatest assets is its ability to fabricate micro/nano-structures in polymers or modify a material without the need for a mask, thus giving it a rapid prototyping capability.In this work, we report on the application of P-beam writing to fabricate passive and active optical waveguides. Passive waveguides in polymers, such as EPON SU-8 and polymethylmethacrylate (PMMA) and active waveguides (i.e. waveguide amplifiers) in Schott IOG-1 Erbium/Ytterbium co-doped phosphate glass were fabricated and characterized. Important fabrication parameters and procedures (such as the stage scanning speed, the optimum dose, the mechanisms for waveguide formation using a focused proton beam etc.) were established and understood. In addition, the waveguide characterization work involves the measurement of the near-field mode profiles, the propagation losses, the recovery of the refractive index profiles of buried PMMA and IOG-1 waveguides and the net gain measurements of the IOG-1 waveguide amplifiers. Future directions and developments on this work will also be presented.