Abstract: A method is provided for detecting an operational condition of a vessel containing two fluid phases moving past each other. The method may include providing a fiber optic cable around an exterior surface of the vessel, receiving time domain data comprising distributed acoustic sensing measurements from the fiber optic cable at a plurality of locations along the exterior surface of the vessel, determining frequency domain data at each of the plurality of locations based on the time domain data, performing an analysis of the frequency domain data and/or the time domain data using a pre-trained model, and determining the operational condition of the vessel based on the analysis.

Abstract: A silicon-based photonic crystal includes a silicon substrate, a first dielectric with a grating structure formed therein, and a second dielectric with a higher index of refraction that covers at least a portion of the grating structure. The first dielectric can be formed on the silicon substrate, or a Fabry-Perot optical cavity can be formed between the silicon substrate and the first dielectric. An instrument can excite a fluorophore coupled to the photonic crystal by focusing collimated incident light that includes the fluorophore's excitation wavelength to a focal line on the surface of the photonic crystal such that the focal line is substantially parallel to the grating direction and can detect fluorescence radiation emitted by the fluorophore in response to the incident light. To provide for fluorescence enhancement, the excitation wavelength and/or emission wavelength of the fluorophore can couple to an optical resonance of the photonic crystal.

Abstract: A silicon-based photonic crystal includes a silicon substrate, a first dielectric with a grating structure formed therein, and a second dielectric with a higher index of refraction that covers at least a portion of the grating structure. The first dielectric can be formed on the silicon substrate, or a Fabry-Perot optical cavity can be formed between the silicon substrate and the first dielectric. An instrument can excite a fluorophore coupled to the photonic crystal by focusing collimated incident light that includes the fluorophore's excitation wavelength to a focal line on the surface of the photonic crystal such that the focal line is substantially parallel to the grating direction and can detect fluorescence radiation emitted by the fluorophore in response to the incident light. To provide for fluorescence enhancement, the excitation wavelength and/or emission wavelength of the fluorophore can couple to an optical resonance of the photonic crystal.