Search for: All records

Evanescent field silicon photonics in a silicon-on-insulator or silicon-nitride-on-insulator platforms have been effectively utilized to demonstrate chemical and biosensors over the past decade with applications in the detection of nucleic acids and protein biomarkers for cancers, viruses and infectious diseases, and environmental toxins. By balancing the requirements for efficient low-loss transmission through the waveguide and enhancing light-matter interaction such as with molecules binding on the high index material surfaces in resonant microcavities, slow light and interferometer geometries, various high sensitivity biosensors have been experimentally demonstrated down to few femtograms/ml. various slotted microcavities and waveguides have been experimentally demonstrated. In recent years, subwavelength waveguides have demonstrated high bulk spectral sensitivities approaching ~500nm/RIU (RIU=refractive index unit) in periodic structures with lattice constant (Λ) <<(λ/2n eff ) where n eff is the effective index at wavelength λ. While most experimental demonstrations have been in subwavelength ring resonator geometries, in this research, in addition to experimental demonstration of bulk spectral sensitivity ~775nm/RIU in subwavelength waveguides in interferometer configurations, we investigate optimized geometries that can reach sensitivities ~70,000nm/RIU in compact dimensions. In contrast to Mach-Zehnder interferometer (MZI) sensors of the same geometric interferometer arm lengths, the reflected path in Michelson interferometers (MI) doubles the optical path length, and thus effectively doubles the phase shift in the presence of an analyte. The interference fringe linewidths are narrowed compared to the equivalent MZI and would thus enable smaller changes in analyte concentration to be discerned from the fringe spectra. 

We experimentally demonstrated slow wave enhanced phase and spectral sensitivity in asymmetric Michelson interferometer sensors with a phase sensitivity 277,750 rad/RIU-cm and theoretical phase sensitivity as high as 461,810 rad/RIU-cm. In the context of low-cost chip integrated photonic packaged sensors, in this paper we will experimentally demonstrate a method for active tuning of interferometer fringes using phase change materials that will potentially overcome fabrication induced variation of interference fringe wavelengths, thus allowing sensor chip packaging with a fixed wavelength laser and available integrated photodetectors. 

The topic of engineering identity is neither new nor complete in its coverage within current literature. In fact, although this body of work predates the last ten years, researchers have argued that some of the most significant burgeoning in this area has occurred in the last decade. By applying both quantitative and qualitative lenses to this inquiry, researchers have concluded that, much like a STEM identity, an engineering identity describes how students see themselves, their competence and potential for success in the academic and career context of the field. To further examine the latter component i.e. potential for academic and career success, we attend to an emerging concept of an entrepreneurial engineering identity. This preliminary work unfolded organically; the authors’ primary goal involved a larger Interpretative Phenomenological Analysis (IPA) study that investigated persistence and advanced degree aspirations among 20 Black male engineering undergraduate students from a variety of institutional settings. While we did not intentionally seek to examine this emerging component of engineering identity, our preliminary analysis of participants’ interview data led us down this path. What we observed was a latent phenomenon of interest among participants: these Black male engineering undergraduates recurringly articulated clear intentions for academic and career opportunities that integrated business components into their engineering realities. Kegan’s (1984, 1994) Theory of Meaning-Making provided a framework for understanding how participants perceived the development of business acumen as a strategy for ascending existing corporate/organizational structures, creating new business pathways, and promoting corporate social responsibility. Based on these findings, the authors were inspired to explore the conceptual development of an entrepreneurial engineering identity and its practical application to engineering degree (re)design, student academic advisory and career planning.