Al nanogrid electrode for ultraviolet detectors.

Optical properties of Al nanogrids of different pitches and gaps were investigated both theoretically and experimentally. Three-dimensional finite-difference time-domain simulation predicted that surface plasmons at the air/Al interface would enhance ultraviolet transmission through the subwavelength gaps of the nanogrid, making it an effective electrode on GaN-based photodetectors to compensate for the lack of transparent electrode and high p-type doping. The predicted transmission enhancement was verified by confocal scanning optical microscopy performed at 365 nm. The quality of the nanogrids fabricated by electron-beam lithography was verified by near-field scanning optical microscopy and scanning electron microscopy. Based on the results, the pitch and gap of the nanogrids can be optimized for the best trade-off between electrical conductivity and optical transmission at different wavelengths. Based on different cutoff wavelengths, the nanogrids can also double as a filter to render photodetectors solar-blind.

Optical injection modulation of quantum-dash semiconductor lasers by intra-cavity stimulated Raman scattering.

We report the optical injection modulation of semiconductor lasers by intra-cavity stimulated Raman scattering. This mechanism manifests itself as sharply enhanced modulation bandwidth in InAs/InGaAlAs/InP quantum-dash lasers when the injected photons are 33 +/- 3 meV more energetic than the lasing photons. Raman scattering measurements on the quantum-dash structure and rate equation models strongly support direct gain modulation by stimulated Raman scattering. We believe this new bandwidth enhancement mechanism may have important applications in optical communication and signal processing.

Microchambers for cell exposure: from the design to applications.

In the last decades, the advances in the micro and nano fabrication techniques have led to the development of microdevices that improved the possibility of analysis at cell level. These devices can be used in different applications (e.g., cell detection and identification, manipulation, cell treatments). The requisites, that are necessary to achieve, are different for various applications and represent the starting point of the project. The numerical multiphysics models can be very advantageous to analyze the performances of such devices and to predict their operation. Aim of this work is to give a look of the design rules of microchamber devices in particular for their application in electric field exposure. Two different applications for cell discrimination and characterization are reported considering time and frequency domain measurements.