An InP ring resonator with an experimentally demonstrated quality factor (Q) of the order of 10(6) is reported for the first time. This Q value, typical for low loss technologies such as silica-on-silicon, is a record for the InP technology and improves the state-of-the-art of about one order of magnitude. The cavity has been designed aiming at the Q-factor maximization while keeping the resonance depth of about 8 dB. The device was fabricated using metal-organic vapour-phase-epitaxy, photolithography and reactive ion etching. It has been optically characterized and all its performance parameters have been estimated. InP waveguide loss low as 0.45 dB/cm has been measured, leading to a potential shot noise limited resolution of 10 °/h for a new angular velocity sensor.

Structural and optical properties of thin InGaAsN insertions in GaAs, grown by molecular beam epitaxy using an RF nitrogen plasma source, have been investigated. Nitrogen incorporation into InGaAs results in a remarkable broadening of the luminescence spectrum as compared with that of InGaAs layer with the same indium content. Correspondingly, a pronounced corrugation of the upper interface and the formation of well defined nanodomains are revealed in cross-sectional and plan-view transmission electron microscope (TEM) images, respectively. Raising the indium concentration in InGaAsN (N < 1 %) to 35 % results in the formation of well defined separated three-dimensional (3D) islands. The size of the nanodomains proves that the InGaAsN insertions in GaAs should be regarded as quantum dot structures even in the case of relatively small indium concentrations (25 %) and layer thicknesses (7 nm), which are below the values required for a 2D-3D transition to occur in InGaAs/GaAs growth. Dislocation loops have been found in TEM images of the structures emitting at 1.3 µm. They are expected to be responsible for the degradation of the luminescence intensity of such structures in agreement with the case of long-wavelength InGaAs-GaAs quantum dots.

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We demonstrate a fully integrated polarization beam splitter with a polarization extinction ratio above 25dB for both polarization states and an insertion loss of 2.5dB. The footprint of the device including electrical contacts is 0.4×2mm2. A Mach-Zehnder configuration is used, the birefringence in both arms differs due to different waveguide widths. Fabrication tolerances can be compensated with thermal tuning. The device is realized in our generic integration platform, making it viable to provide monolithically integrated solutions for polarization diversity applications

We report on the fabrication and characterization of a monolithically integrated balanced mixer receiver on InP consisting of a 3-dB coupler, twin balanced waveguide integrated photodiodes, and a low-noise electrical preamplifier. The receiver OEIC exhibits a transimpedance of 223 Omega and a 3-dB bandwidth of 1 GHz. Heterodyne operation and local laser noise cancellation capability of the OEIC are demonstrated