Dr. Matthew J. Grant Profile

Dr. Matthew J. Grant

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Publications (5)

Proceedings Article | 3 March 2022 Presentation + Paper

Chip-scale gyroscope using silicon-nitride waveguide resonator with a Q factor of 100 million

Matthew Grant, Pierre-Baptiste Vigneron, Avi Feshali, Warren Jin, Nathan Abrams, Mario Paniccia, Michel Digonnet

Proceedings Volume 12016, 120160S (2022) https://doi.org/10.1117/12.2617219

KEYWORDS: Backscatter, Gyroscopes, Resonators, Sensors, Waveguides, Laser resonators, Interference (communication), Modulation, Signal detection, Continuous wave operation

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Proceedings Article | 5 April 2021 Presentation + Paper

Resonant exceptional-point gyroscopes

Matthew Grant, Michel J. F. Digonnet

Proceedings Volume 11700, 117002M (2021) https://doi.org/10.1117/12.2589741

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Operating an optical device at an EP causes small perturbations  applied to the device’s optical path length to produce a greatly enhanced splitting of resonance frequencies due to the splitting being proportional to  at the EP, instead of  as for conventional devices. For increasingly small  , the EP splitting can therefore be larger by several orders of magnitude by operating sufficiently close to the EP. This enhanced splitting has drawn great interest recently, in particular for the potential to miniaturize the optical gyroscope. However, a small but growing number of publications claim that EP sensors may not achieve a proportionally larger signal-to-noise ratio once the full readout system and noise is accounted for. Many different EP sensors have been proposed, some as passive resonators, others as resonators with internal gain operated either below or above lasing threshold. Each sensor class may use a different readout system to measure the splitting and is therefore subject to different noise, but the recent trend has been that once noise and readout system have been accounted for, the enhanced  response cancels out and a signal-to-noise ratio proportional to  is achieved. Despite this cancellation, enhanced precision in EP sensors has still been predicted, although there is disagreement in whether the enhancement arises from the EP or another aspect of the sensor’s architecture, such as the gain. In this paper, we demonstrate through simulations that the EP in two-coupled-mode resonant (below lasing threshold) gyroscopes plays no role in enhancing the signal-to-noise ratio. An all-passive EP gyro is simulated in the limits of shot noise and detector noise to show that in either of these noise limits, no improvement in SNR over the equivalent single-ring gyro is possible. One of the rings is then given gain to show that a large enhancement in detectornoise- limited SNR (~2400 fold) arises, but close proximity to the EP is not necessary to maximize this enhancement; the enhancement is actually significantly larger when the sensor is detuned from the EP. This gain-loss gyro is then compared to a single-ring gyro with gain to show that large sensitivity enhancements are possible in both architectures because the gain compensates the resonator loss, resulting in a narrowing of the resonance linewidth and a greater response to a rotation, but the coupled-ring gyro exhibits a much greater stability to gain fluctuations.