In this study, we numerically investigate the formation dynamics of clustered optical frequency combs (OFCs) in a Kerr microresonator using the Lugiato–Lefever equation (LLE). We demonstrate that both pump power and resonator finesse influence the generation of these clustered OFCs.

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Step-frequency radar represents a potential alternative sensor modality for non-invasive heart monitoring, with the aim of developing low-cost and easily portable technology for continuous monitoring of heart activity by sensing the motion of the heart surface as a radar-reflective target. This paper reports on an attempt to account for the deviation of the waveform of the traveling signal from the simple plane-wave approximation typically used for far-field radar, due to the limited distance between the radar source of a chest-mounted sensor and the internal target of the heart surface. Accordingly, this study applied a modification to the discrete Fourier transform converting received frequency-domain data into travel-time-domain data to be used in assessing the distance of reflective targets from the radar via modification of the approximate representation of the radar signal from a plane wave to a spherical wave.

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