Sandia_Natl_Labs_FY19_LDRD_Annual_SAND2020-3752 R_2_S


Assessing seismic analysis and analyst performance using the normalized compression distance metric. This project brought together a multi-center, interdisciplinary team to achieve a cutting- edge technical advance. They successfully applied the normalized compression distance metric (NCD) to seismic waveform data and demonstrated that this technique can accurately identify the onset of seismic events, particularly those caused by explosions and nuclear tests. They compared the peak of the NCD metric to an expert seismic analyst’s assessment of the range of possible event onset times for 543 seismic waveforms and found that the NCD peak fell within the analyst’s range for 75% of the seismic stations in the data set and was within 0.1 seconds of that range for 87% of the stations. In addition, they compared NCD to the algorithm that is currently used for automatic event detection and found that NCD provides more accurate results than the state-of-the-art method. A truly micro-scale gyroscope based on optomechanical oscillation. A Sandia-led team designed, fabricated, and tested optomechanical oscillators for gyroscopes. These devices utilize pressure from light stored in a cavity to induce mechanical oscillation of the cavity. Through fabrication improvements, they achieved optical cavity Q greater than three million in free-standing micro-structures and achieved optomechanical oscillation with threshold pumping power less than 200µW. US Patent 10,458,795 was granted for the novel use of optomechanical oscillators as micro-scale gyroscopes. Devices were fabricated on a silicon chip and device radii as small as 20µm were characterized. They experimentally investigated the scaling behavior for both the gyroscope sensitivity and noise and found that the sensitivity is currently limited by residual optical absorption. Improvements are suggested to realize the goal of a micro-scale, gyroscope. They also initiated glass doped with phosphorous as a new foundational optical material capability at Sandia. The team demonstrated process improvements including void-free thermal melting of glass to smooth thousands of optical resonators simultaneously on a wafer.

Left: Phosphorous-doped glass device created to be mirror smooth after melting in a furnace Right: Fabricated chips each containing more than 72 unique devices



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