In the amphibian auditory system, a subset of hair cells is known to be frequency tuned via electrical resonance. This tuning is thought to contribute to frequency selectivity of the information leaving the auditory periphery via the auditory afferent fibers. At the same time, while most, if not all, afferent fibers are shown to be frequency tuned, electrical resonance has only been experimentally demonstrated in a subset of amphibian auditory hair cells. In this thesis, we validate and use a novel Zap current method to probe the electrical resonance of the bullfrog amphibian papilla hair cells. We uncover the existence of two previously unknown types of electrically resonant auditory hair cells. We then show the existence of resonant hair cells across the length of amphibian papilla, with the range of frequency tuning that is nearly indistinguishable from that previously reported in the of auditory fibers. Therefore, this work further validates amphibian hair cell frequency resonance as the possible mechanism underlying frequency selectivity of the subsequent stages in auditory signal transduction.

Various nanostructured materials display unique and interesting optical properties. Specific nanoscale objects discussed in an experimental perspective in this dissertation include optical metamaterials, surface plasmon sensors, and two-dimensional materials. These nanoscale objects were fabricated, investigated optically, and their applications are assessed. First, one-dimensional magnetic gratings were studied, followed by their two-dimensional analog, the so-called "fishnet." Both were fabricated, characterized, and their properties, such as waveguiding modes, are examined. Interestingly, these devices can exhibit optical magnetism and even negative refraction; however, their general characterization at oblique incidence is challenging due to diffraction. Here, a new method of optical characterization of metamaterials which takes into account diffraction is presented. Next, surface plasmon resonance (SPR) was experimentally used in two schemes, for the first time, to determine the transition layer characteristics between a metal and dielectric. The physics of interfaces, namely the singularity of electric permittivity and how it can be electrically shifted, becomes clearer owing to the extreme sensitivity of SPR detection mechanisms. Finally, ultra-thin two-dimensional semiconducting materials had their radiative lifetime analyzed. Their lifetimes are tuned both by number of atomic layers and applied voltage biasing across the surface, and the changes in lifetime are suspected to be due to quenching or enhancement of non-radiative process rates.