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This paper proposes a new class of resonant tunneling diodes (RTDs) that are planar and realizable with a single graphene nanoribbon. Unlike conventional RTDs, which incorporate vertical quantum well regions, the proposed devices incorporate two confined planar quantum dots within the single graphene nanoribbon, giving rise to a pronounced negative differential resistance (NDR) effect. The proposed devices, termed here as planar double-quantum-dot RTDs, and their transport properties are investigated using quantum simulations based on nonequilibrium Green’s function formalism and the extended Huckel method. The proposed devices exhibit a unique current–voltage waveform consisting of a single pronounced current peak with an extremely high, in the order of $10^{4}$ , peak-to-valley ratio. The position of the current peak can be tuned between discrete voltage levels, allowing digitized tunability, which is exploited to realize multi-peak NDR devices.

Optical delay and corresponding group index of structure composed of slab waveguide coupled with slotted ring resonator are investigated in this paper. Ring resonators have attracted a lot of attention to develop optical delay line which has numerous applications in communication. Properties of these micro ring resonators are highly dependent on waveguide geometry and can be tailored for various applications with minor changes. This paper investigates performance of single and multi stage ring resonators by manipulating geometry and gap between slab and ring waveguide for single mode propagation which may assist to make well informed decisions in the selection process of best-suited ring waveguide for particular application. This investigation is further extended to verify the tolerance of the design in case of fabrication errors with dimension of ±10nm.

Change in refractive index and corresponding change in optical properties like propagation loss, group index and dispersion in active PIN silicon waveguide with and without photonic crystal core are investigated by changing doping concentration. This investigation sets a bound on doping density which is utilized to change effective refractive index for various applications like modulation, switching, dispersion compensation, slowing light and so on. Influences of depleting carriers on junction capacitance and reverse current behaviors are also investigated for same waveguides. This sets a benchmark for the design and selection of appropriate waveguide for various applications in silicon photonics platform.

This paper reviews some of the research work we have carried out in the transport of broadband OFDM signals using digitized wireless signal transport in a fiber-wireless environment. We compare the performance against analog transport strategy.

This paper presents a computationally efficient method to forecast floods stochastically. The main purpose of the method is to encapsulate prior knowledge as off-line calculations leading to earliest possible warnings. The computational efficiency is improved through exploiting the stereotypical features of hydrology and its dependence on topography by combining the parallel water-flow processes into parallel calculation through a probability transition matrix. Efficiency is improved further with the use of properties of Markov matrices in the general equation of the model. Extensive simulations on real rainfall data over parts of Queensland, Australia, during January 2012, revealed that this method was capable of improving the calculation efficiency by over 18 times with respect to gradient based calculations.

This paper presents analysis on optimum drive amplitudes and wavelength stability in a novel scheme for dual baseband generation using a single laser and a modulator considering receiver sensitivity and error floors arising due to optical filtering.

We propose a simple and stable seeding source that enables ultra dense WDM-PON based on injection locking devices and for the first time experimentally demonstrate a 12.5 GHz channel spaced DWDM-PON with 1.25 Gb/s transmission.

We demonstrate a wavelength reuse scheme facilitated through sub-carrier downstream transmission that achieves source free optical network units in a WDM-PON. The scheme only requires baseband detection for both downstream and upstream data recovery.