Princeton University

School of Engineering & Applied Science

Noise Mitigation Techniques for High-precision Laser Spectroscopy and Integrated Photonic Chemical Sensors

Eric Zhang
Engineering Quadrangle B327
Wednesday, October 26, 2016 - 1:00pm to 2:30pm

Laser spectroscopy has shown considerable utility in the monitoring of trace-gas species for environmental and health applications. In contrast to traditional laboratory diagnostics (eg. gas chromatography, mass spectrometry, electrical/chemical sensors), optical platforms provide non-invasive and in-situ sensing capabilities, rendering them attractive for on-site, real-time diagnostics. In this talk we introduce precision enhancements techniques in optical sensing, with particular focus on Faraday rotation spectroscopy (FRS) for detection of radical species. Using a combination of phase-sensitive, balanced optical detection and polarizer optimization, these sensors consistently demonstrate near shot-noise performance and excellent long-term stability, with sensitivities ~102× beyond what is achievable using conventional absorption techniques. Towards the conclusion of the talk, we discuss the development of next-generation integrated photonic sensors and techniques for noise reduction on these new sensing platforms. An initial demonstration of on-chip spectroscopy for methane fugitive emissions monitoring will be presented, along with a vision towards fully integrated silicon-photonic chip sensors.