Ultra-high-sensitivity Resonant Photonic Sensors through Brillouin Scattering Induced Transparency

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The goal of this project is to demonstrate micro-sensors for measurements of temperature and pressure, with sensitivities that far exceed what is achievable with existing technologies. This research can help to develop better sensor technologies for a variety of applications including information storage, communications, and medical diagnosis. This project provides many opportunities for the interdisciplinary training of students at 
all academic levels. The STEM impact of this work will be broadened through the development and distribution of educational modules for high-school girls at an 
engineering summer camp held at UIUC. Undergraduate research assistants will be recruited to assist in the development of the prototype sensors via summer research programs. The educational activities produced through this grant will be widely distributed through existing outreach mechanisms at UIUC.Optical microresonators are frequently used for physical sensing, including measuring mass, displacement, and extremely small forces. The typical sensing method relies upon monitoring the shift of the optical resonance frequencies due to applied physical stimuli. The sensitivity of these measurements is fundamentally limited by the optical losses intrinsic to the material. In this proposal, Brillouin scattering will be investigated in order to overcome these material limitations. The PI recently demonstrated that a strong optical dispersion effect can be generated through Brillouin scattering of a ?control? laser from a traveling acoustic wave within a micro-resonator. This phenomenon results in the creation of a spectrally-narrow transparency window in a neighboring optical mode. An extremely rapid gradient in phase-response accompanies this transparency, and can be measured with a weak ?probe? laser. This rapid gradient provides high sensitivity to small fluctuations in optical and acoustic resonance frequencies due to physical stimuli. The PI will develop analytical models to describe the effects of physical stimuli on the optical dispersion characteristics. The models will be experimentally tested on multiple resonator platforms, including silica microspheres and shell microcapillary resonators. Additional experiments will be performed to enhance the pressure sensitivity of deformable optical resonators, and to use slow light for physical sensor applications.