This paper presents a study of the absorption of electromagnetic power that results from the interaction of electromagnetic waves and cylindrical bumps or trenches on flat conducting surfaces. Configurations are characterized by means of adequately selected dimensionless variables and parameters so that applicability to mathematically equivalent (but physically diverse) systems can be achieved easily. Electromagnetic fields and absorption increments caused by such surface defects are evaluated by means of a high-order integral equation method which resolves fine details of the field near the surface, and which was validated by fully analytical approaches in a range of computationally challenging cases. The computational method is also applied to problems concerning bumps and trenches on imperfect conducting planes for which analytical solutions are not available. Typically, we find that absorption is enhanced by the presence of the defects considered, although, interestingly, absorption can also be significantly reduced in some cases-such as, e.g., in the case of a trench on a conducting plane where the incident electric field is perpendicular to the plane. Additionally, it is observed that, for some small-skin-depths large-wavelengths, the absorption increment is proportional to the increase in surface area. Significant physical insight is obtained on the heating that results from various types of electromagnetic incident fields. V C 2014 AIP Publishing LLC. [http://dx.

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A method for obtaining non-Gaussian light beams with azimuthal field polarisation in a waveguide quasi-optical cavity is described. The method is based on the employment of polarisation-selective diffraction structures as laser mirrors. Efficient excitation of such beams at the output from an optically pumped waveguide HCOOH laser (λ = 0.4326 mm) with an inhomogeneous reflecting input and semitransparent output mirrors is confirmed theoretically and experimentally.