This project, based on collaboration with the University of Southampton in the United Kingdom, seeks to improve the materials quality of compound semiconductor and amorphous hydrogenated group IV semiconductor optical fibers such that they become useful for a wide range of applications, including non-linear optical processing, subwavelength imaging, and fiber lasers. Current semiconductor optical fibers have losses in excess of 1 dB/cm, which is often considered to be the threshold loss for practical application in many semiconductor photonic devices. The grain boundary scattering that is the primary loss mechanism in compound semiconductor fibers will be reduced by improving in-fiber materials deposition techniques that the US/UK groups have pioneered. The loss in hydrogenated silicon and germanium fibers will also be reduced by eliminating voids that lead to light scattering in fiber cores and improving materials deposition techniques to allow for better passivation of defects that give rise to loss. The second and third order non-linear optical properties of these improved low loss compound semiconductor and amorphous hydrogenated group IV semiconductor fibers will be characterized with a view toward non-linear optical devices. Core cladding fiber structures composed of these materials will also be fabricated for sub-wavelength, high resolution infrared imaging. New compound semiconductor fibers with different compositions will also be deposited to extend the range of materials properties that can be exploited in the fiber geometry.
This project brings together the complementary expertise in materials synthesis and structural and optical characterization of the Penn State team and with the expertise in guided wave devices of the Southampton team. Students will travel in both directions across the Atlantic for visits of a few weeks to a month to maintain the strong collaborative ties between the two groups. These visits will supplement ongoing collaborative interactions via web-based discussions and presentations as well as computer-based video conferencing. US students will be exposed to the world class fiber fabrication and characterization facilities at the Southampton Optoelectronics Research Centre. UK students will learn about materials synthesis and characterization at Penn State. This natural partnership is anticipated to move the field of crystalline semiconductor and amorphous hydrogenated semiconductor fibers towards practical application through the proposed materials research. Outreach efforts include visits to local schools, hosting undergraduate students in the Penn State Laboratories, and participation by the PI's and students in hands-on science camps hosted at Penn State for students from grades 2-12. These camps have substantial participation by underrepresented groups and provide high quality, highly engaging science instruction for all attendees.