In this work we describe the carrier depletion MZI modulators, slow wave structures for modulation enhancement and the QCSE modulator which are under development in the European HELIOS project and the UK Silicon Photonics project.
We report the direct determination of nonradiative lifetimes in Si/ SiGe asymmetric quantum well structures designed to access spatially indirect ͑diagonal͒ interwell transitions between heavy-hole ground states, at photon energies below the optical phonon energy. We show both experimentally and theoretically, using a six-band k · p model and a time-domain… (More)
—Producing an electrically pumped silicon-based laser at terahertz frequencies is gaining increased attention these days. This paper reviews the recent advances in the search for a silicon-based terahertz laser. Topics covered include resonant tunneling in p-type Si/SiGe, terahertz intersubband electroluminescence from quantum cascade structures,… (More)
—Methods for systematic optimization of step-graded and continuously graded ternary alloy based quantum wells (QW's), in respect to second-or third-order intersubband non-linear susceptibilities at resonance, are discussed. The use of these methods is examplified on the design of Al x Ga 10x N and Al x Ga 10x As-based QW's intended for resonant second… (More)
Remarkable progress in terahertz (THz) technology over the past decade has been driven by the potential applications of THz waves in areas such as biomedical imaging, long-range screening, and organic materials identification . This growth is in no small measure related to the success of the quantum cascade laser (QCL) which has established itself as one… (More)
Copyright and reuse: The Warwick Research Archive Portal (WRAP) makes this work of researchers of the University of Warwick available open access under the following conditions. This article is made available under the Creative Commons Attribution-3.0 Unported (CC BY 3.0) license and may be reused according to the conditions of the license. For more details… (More)
We report on the effects of growth variations on the computed electroluminescence of Ge/SiGe chirped superlattice quantum cascade structures. The chirped structures investigated comprise 50 periods, each of which has a sequence of 5-7 Ge quantum wells and SiGe barriers. We used an extended density matrix carrier transport model to calculate the electron… (More)