The creation of monolithically integratable sources of single and entangled photons is a top research priority with formidable challenges: The production, manipulation, and measurement of the photons should all occur in the same material platform, thereby fostering stability and scalability. Here we demonstrate efficient photon pair production in a semiconductor platform, gallium arsenide. Our results show type-I spontaneous parametric down-conversion of laser light from a 2.2 mm long Bragg-reflection waveguide, and we estimate its internal pair production efficiency to be 2.0×10(-8) (pairs/pump photon). This is the first time that significant pair production has been demonstrated in a structure that can be electrically self-pumped and which can form the basis for passive optical circuitry, bringing us markedly closer to complete integration of quantum optical technologies.

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We demonstrate a high speed GeSi electro-absorption (EA) modulator monolithically integrated on 3 µm silicon-on-insulator (SOI) waveguide. The demonstrated device has a compact active region of 1.0 × 55 μm(2), an insertion loss of 5 dB and an extinction ratio of 6 dB at wavelength of 1550 nm. The modulator has a broad operating wavelength range of 35 nm and a 3 dB bandwidth of 40.7 GHz at 2.8 V reverse bias. This compact and energy efficient modulator is a key building block for optical interconnection applications.

Techniques used to assist phase matching of second-order nonlinearities in semiconductor waveguides are reviewed. The salient points of each method are highlighted, with their strengths and weaknesses with regard to various key applications discussed. Recent progress in these techniques is also reviewed. Emphasis is placed on two techniques, namely quasi-phase matching via domain disordering utilizing quantum well intermixing, and exact phase matching using Bragg reflection waveguides.The figure shows (a) An optical microscope image of an ion implantation mask used to fabricate gratings used for quasiphase matching, (b) a scanning electron micrograph of an ion implantation mask, (c) a scanning electron micrograph of a semiconductor ridge waveguide structure, and (d) an optical microscope image of group monolithic ring lasers designed for integration with quasiphase matched structures.

What we believe to be the first demonstration of an edge-emitting Bragg reflection waveguide laser is reported. The laser utilized InGaAs quantum wells emitting at 980 nm, with Al(x)Ga(1-x)As core and claddings. The lasing mode is centered in a low-index core with a width of 700 nm, hence providing a large mode volume with strong discrimination against any modes other than the fundamental photonic bandgap mode. Single-transverse mode operation is observed with thresholds as low as 157 A/cm(2). The propagation losses of the mode were measured for the first time and found to be 11.4 cm(-1).