Overview
Polymer materials are generally recognized to exhibit various favorable properties for the use in optical waveguide technology. There is a great potential for the use of polymers in terms of optical properties, cost-effectiveness, and processing possibilities. Optical polymers are versatile materials that can be readily formed into planar single-mode and multimode waveguides. With regard to optical interconnect applications polymers have to fulfill tight requirements, such as very low optical losses and the compatibility with printed circuit board manufacturing processes (e.g. resilience against solder reflow and lamination process).
The optical propagation distance we anticipate is in the range of 30 to 100 cm and therefore the propagation losses should be below 0.05 dB/cm. Allowing for these low losses and the required compatibility with PCB manufacturing, we evaluated different photosensitive polymer materials that are mainly based on acrylates and siloxanes. The deposition of the liquid polymeric layers as claddings and waveguide cores on conventional FR4 substrates was done by doctor blading as well as by spray coating. The patterning of the core layer was performed by laser direct writing or photolithography and subsequent wet-chemical developing.
