SRP Abstracts

Julia Gelfond '23, et al., Highly Electrically Conductive Biomass-derived Carbon Fibers (Sustainable Materials and Technologies)

• ISEF 2023, 2nd Place Award in Chemistry

I developed a novel process to create bamboo cellulose derived carbon fibers via Joule-heating, based on my hypothesis that Joule-heating repairs defects in carbonized bamboo fibers by providing energy for atomic-scale reorganization of carbon atoms into conductive graphite crystals. Joule-heating is a method of quick ohmic heating that can achieve high temperatures of ~2000°C within a few seconds and it’s really fun to do/watch! Carbon fibers are highly conductive, and chemically inert, making them useful in many diverse applications. Currently, however, most carbon fiber is derived from fossil fuel precursors, and many biomass-derived carbon fibers fall short in producing high electrical conductivities. If viable processes could be developed to produce carbon fiber from biomass, sequestering carbon from the atmosphere would be an additional benefit. Carbon fibers made with my process were characterized by scanning electron microscopy, thermogravimetric analysis, Raman spectroscopy, and conductivity measurements, and demonstrate high electrical conductivity (25,300 ± 6270 S/m). This scalable process could also sequester significantly more carbon compared to existing carbon fiber production methods because it comes from biomass and bamboo in particular. Compared to existing biomass-derived carbon fibers, the fabrication method I developed is inexpensive and produces fibers with very high electrical conductivity, suggesting my fibers could be used in low-cost, high quantity applications such as smart construction, composites made with resin or thermoplastic impregnation, conductive textiles, and battery anodes.

Christy Li '23: Optimal Design of Arbitrary Waveguide Bends for Footprint-Efficient and Low-Loss Silicon Photonic Resonators

• JSHS 2023, 2nd Place Oral Presentation Award for Physical Sciences

Integration of photonics components onto chips has revolutionized modern data communications and sensing, as it allows for the mass fabrication of devices which can transmit and guide light at the scale of the wavelength of the light itself. Circular ring resonators, in particular, are used to transform continuous input light into pulse trains which find applications in accurate time keeping, distance ranging, sensing, and metrology. The implementation of “racetrack” resonators has long been proposed as a footprint-efficient alternative to circular rings, however their dispersion—which must be controlled for stable pulse generation—is more difficult to engineer because they lack the radial symmetry of rings, making straightforward design a challenge. I address this problem by presenting a differential application of transformation optics from bulk propagation modified for nanophotonics. This mathematical transformation will be used to unravel periodic resonators such as racetracks into straight-waveguide tapering optimization problems which are simple to dispersion engineer, opening the door for intuitive design and simulation of previously inaccessible resonator structures. This unprecedented control over light-matter interaction in resonators will allow for the design of footprint-efficient racetracks for quantum frequency conversion, synthetic frequency dimensions, and frequency comb generation.