Investigation into the integration of a resonant tunnelling diode and an optical communications laser: model and experiment

A resonant tunnelling diode has been monolithically integrated with an optical communications laser [the resonant tunnelling diode (RTD-LD)] to form a simple optoelectronic integrated circuit (OEIC) that is a novel bistable device suitable for an optical communications system. The RTD-LD was based on a ridge-waveguide laser structure and was fabricated from an InAlGaAs-InP epi-wafer grown by molecular beam epitaxy; it emitted at around 1500 nm. Voltage controlled optical-electrical switching and bistability were observed during the characterisation of the RTD-LD - useful features for a fibre-optic communications laser. Optical and electrical simulations of the RTD-LD were carried out using the circuit simulation tool PSPICE. In addition, a discrete component version of the RTD-LD was constructed which exhibited optical power oscillations, and along with the results of the simulations, gave insight into the operating principles of the monolithically integrated RTD-LD

The British Empire and the hajj 1865-1939

The 1861 cholera epidemic, which began in India and swept through Europe, carried by pilgrims on their way to Arabia to perform the hajj, was the catalyst for greater British involvement with the fifth pillar of Islam. British interaction with the hajj, which began with supervising the quarantine stations that were established at Arabia's maritime gateways, developed into a bureaucratic apparatus spread over Britain's Muslim territories, as well as the British Consulate in Jedda. This bureaucracy attempted to regulate various aspects of the hajj experience. Preventing the spread of epidemic disease remained a primary concern, but other duties the British took upon themselves were assistance to so-called 'pauper pilgrims' from British territories stranded in Arabia and monitoring the traffic of slaves to Arabia who were passed off as pilgrims. As Britain became the ruler of the largest number of Muslims in the world in the early twentieth century, it became acutely conscious of its expanded role in facilitating the smooth operation of the hajj each year, as an advertisement to its Muslim subjects that Britain was sensitive and supportive towards Islam. British sensitivity towards this Islamic ritual was further shown in its sponsoring of Indian Muslim soldiers based in Egypt to perform the hajj during the First World War.British Academ

Integration of a resonant tunneling diode and an optical communications laser

We report on the first integration of a resonant tunneling diode and an optical communications laser operating at around 1.5 /spl μm. We demonstrate its low-frequency bistable operation and model its electrical characteristics

Quantum cascade lasers with an integrated polarization mode converter

We discuss the design, fabrication and characterization of waveguide polarization mode converters for quantum cascade lasers operating at 4.6 μm. We have fabricated a quantum cascade laser with integrated polarization mode converter that emits light of 69% Transverse Electrical (TE) polarization from one facet and 100% Transverse Magnetic (TM) polarization from the other facet