Deep Proton Writing: a rapid prototyping polymer microfabrication tool for micro-optical modules

One of the important challenges to deploying the emerging breed of nanotechnology components is interfacing them with the external world, preferably accomplished with low-cost micro-optical devices. In our labs at the Vrije Universiteit Brussel (VUB), we are therefore focusing on the continuous development of a rapid prototyping technology for the fabrication of micro-optical modules. In this technology, which we call deep proton writing (DPW), we bombard polymer samples with swift protons, which will result after chemical processing steps in high quality micro-optical components. The strength of the DPW micro-machining technology is the ability to fabricate monolithic building blocks that include micro-optical and mechanical functionalities which can be precisely integrated into more complex photonic systems. The DPW technology is furthermore compatible with low-cost mass-replication techniques such as microinjection moulding and hot embossing. In this paper we give an overview of the process steps of the technology and the characteristic qualities we can expect from the components made by DPW. The general overview of the technology is followed by three case studies of different micro-optical components that were fabricated at our labs: (i) two-dimensional fiber connectors, (ii) out-of-plane couplers for optical waveguides embedded in printed circuit boards (PCBs), (iii) intra multi-chip-module (MCM) level optical interconnection via free space optical modules.