No abstract

We demonstrate that the group velocity dispersion (GVD) of the supermodes in a small array of silicon photonic wires can differ dramatically from the single wire GVD. This enables soliton propagation and modulational instability to be seen at wavelengths where single wires have strongly normal GVD.

A filter to separate the effect of multipath in Global Navigation Satellite System (GNSS) signal‐to‐noise ratio (SNR) data is presented. The filter removes multipath cleanly, and affects neither slowly varying trends (such as tropospheric absorption or variation in satellite range) nor high frequency components (such as ionospheric scintillation), and so is potentially useful in space‐weather research. Similarly, the multipath data removed from the input data is minimally distorted, and contains useful information as to the multipath geometry. A method to locate reflecting objects using a form of spectral analysis is described.

We report measurements and numerical modeling of spectral broadening and soliton propagation regimes in silicon-on-insulator photonic wire waveguides of 3 to 4 dispersion lengths using 100fs pump pulses. We also present accurate measurements of the group index and dispersion of the photonic wire.

Carbon capture and storage is a transition technology from a past and present fuelled by coal, oil and gas and a planned future dominated by renewable energy sources. The technology involves the capture of carbon dioxide emissions from fossil fuel power stations and other point sources, compression of the CO 2 into a fluid, transporting it and injecting it deep beneath the Earth's surface into depleted petroleum reservoirs and other porous formations. Once injected, the CO 2 must be monitored to ensure that it is emplaced and assimilated as planned and that none leaks back to surface. A variety of methods have been deployed to monitor the CO 2 storage site and many such methods have been adapted from oilfield practice. However, such methods are commonly indirect, episodic, require active signal generation and remain expensive throughout the monitoring period that may last for hundreds of years. A modelling framework was developed to concurrently simulate CO 2 geostorage conditions and background cosmic-ray muon tomography, in which the potential was assessed for using variations in muon attenuation, due to changes in CO 2 abundance, as a means of CO 2 detection. From this, we developed a passive, continuous monitoring method for CO 2 storage sites using muon tomography, the tools for which can be deployed during the active drilling phase (development) of the storage site. To do this, it was necessary to develop a muon detector that could be used in the hostile environment (saline, high temperature) of the well bore. A prototype detector has been built and tested at the 1.1 km deep Boulby potash mine on the northeast coast of England, supported by the existing STFC Boulby Underground Laboratory on the site. The detector is now ready to be commercialized. This article is part of the Theo Murphy meeting issue ‘Cosmic-ray muography’.