Thesis Type:MSc thesis
At the last decade, the wide growth in data transfer realized the requirement of optical communications for its high capacity capabilities. The revolution of optical communications has been enabled by the availability of ultra-low-loss silica fiber, which has also been the basis for a wide variety of optical building blocks.
Fabricating passive optical devices from high purity silica and glass, or fabricating active devices that utilize the direct band gap of semiconductors (SC) are relatively costly; therefore alternative solutions are being studied widely.
Our research is aiming to realize a platform based on passive polymer materials as the wave-guiding material, and in the future to dope it with SC nanocrystals (NC). Plastic (polymers) optical fiber has already found significant application in the Datacom market.
In this work we present the design of optical devices and their fabrication. Polymer selection is critical, as most polymers have CO and CH absorption bands which reside near 1.55m wavelength. A PFCB core and a Cytop as cladding were chosen and combined together for the first time. This two polymers combination offers a very small attenuation at the optical communication wavelength of 1.55m, high Δn and solubility with NC.
At the design process, we focused on realizing devices that will help us extract the basic characteristic of our polymer platform, such as propagation losses, bend losses and reflective index changes that will occur after NC doping.
Realizing polymeric waveguides with a micron-scale cross section of and length of a few centimeters has low defect tolerance which requires careful treatment. Fabrication was done with standard semiconductor process, such as lithography, reactive ion etching etc. Furthermore, a low preparation temperature is critical when heat-sensitive elements, such as semiconductors nanocrystals, are to be embedded in the waveguide. Finally, after the process development, we have the desired polymeric waveguide structure. This waveguide platform is now ready for future study of NC dopants.