Coiled armrings: an Hiberno-Viking silver arm-ring type

The purpose of this paper is to isolate and discuss a distinctive type of Hiberno-Viking silver armring. Here termed the 'coiled armring', it is dated to the late ninth/early tenth centuries. The methods of manufacture, ornamentation, date and origins of the type are discussed and the objects are assessed against the background of hoard-associated material and related types of silver armrings. A descriptive catalogue of the material is provided.

Cavity ring‑up spectroscopy for dissipative and dispersive sensing in a whispering gallery mode resonator

In whispering gallery mode resonator sensing applications, the conventional way to detect a change in the parameter to be measured is by observing the steady-state transmission spectrum through the coupling waveguide. Alternatively, sensing based on cavity ring-up spectroscopy, i.e. CRUS, can be achieved transiently. In this work, we investigate CRUS using coupled mode equations and find analytical solutions with a large spectral broadening approximation of the input pulse. The relationships between the frequency detuning, coupling gap and ring-up peak height are determined and experimentally verified using an ultrahigh Q-factor silica microsphere. This work shows that distinctive dispersive and dissipative transient sensing can be realised by simply measuring the peak height of the CRUS signal, which may improve the data collection rate.