Modelling Space-time Periodic Structures with Arbitrary Unit Cells Using Time Periodic Circuit Theory

Using the time periodic ABCD parameters, an expression for the dispersion relation of space-time modulated structures is obtained. The relation is valid for general structures even when the spatial granularity is comparable to the operating and modulation wavelengths. In the limit of infinitesimal unit cell, the dispersion relation reduces identically to its continuous counterpart. For homogeneous space-time modulated media, the time periodic circuit approach allows the extension of the well-known telegraphist's equations. The time harmonics are coupled together to form an infinite system of coupled differential equations. At the scattering centres, where the interaction is mediated via the modulation (pump wave), the telegraphist's equations reduce to the interaction of two waves only: the signal and idler. The interaction can then be described using three wave mixing, satisfying the phase matching condition. It is demonstrated that the time periodic S parameters provide an alternative and appealing visualization of the modal conversion and the emergence of non-reciprocity inside the bandgaps.Comment: 9 pages, 10 figure

Scattering of electromagnetic waves in metamaterial superlattices

The authors study experimentally both transmission and reflection of microwave radiation from metamaterialsuperlattices created by layers of periodically arranged wires and split-ring resonators. The authors measure the dependence of the metamaterial resonance on the spatial period of the superlattice and demonstrate resonance broadening and splitting for the binary metamaterial structures.The authors acknowledge support from the Australian Research Council and thank Ekmel Ozbay for providing additional details of the experimental results published earlier by his group

Novel pulsed electron spin resonance system and studies of phosphorus in natural silicon

An X-band pulsed electron spin resonance system has been designed and constructed specifically for studies of decoherence times of phosphorus donor electrons in silicon. The microwave electromagnetic field aspects of the structure have been analysed, an