Electronic transport in a series of multiple arbitrary tunnel junctions

Monte Carlo simulations and an analytical approach within the framework of a semiclassical model are presented which permit the determination of Coulomb blockade and single electron charging effects for multiple tunnel junctions coupled in series. The Coulomb gap in the I(V) curves can be expressed as a simple function of the capacitances in the series. Furthermore, the magnitude of the differential conductivity at current onset is calculated in terms of the model. The results are discussed with respect to the number of junctions.Comment: 3 figures, revte

Improvement of the guiding performances of near infrared organic/inorganic channel waveguides

New sol-gel derived organic/inorganic hybrid single mode waveguides devices have been developed for telecommunication applications in the two near infrared windows at 1310 and 1550 nm. The overall procedure of fabrication of these devices is described and the refractive indices of the guiding, the buffer and the protective layers are adjusted by a precise control of the materials' composition. Due to the improvement of the composition of the guiding layer, the attenuation losses are significantly decreased to 0.8 dB/cm and 2dB/cm at respectively 1310 and 1550 nm

Optoelectronic printed circuit board: 3D structures written by two-photon absorption

ABSTRACT The integration of optical interconnects in printed circuit boards (PCB) is a rapidly growing field due to a continuously increasing demand for high data rates, along with a progressive miniaturization of devices and components. For high-speed data transfer, materials and integration concepts are searched for which enable high-speed short-range connections, accounting also for miniaturization, and costs. Many concepts are discussed so far for the integration of optics in PCB: the use of optical fibers, or the generation of waveguides by UV lithography, embossing, or direct laser writing. Most of the concepts require many different materials and process steps. In addition, they also need highly-sophisticated assembly steps in order to couple the optoelectronic elements to the optical waveguides. An innovative approach is presented which only makes use of only one individual inorganic-organic hybrid polymer material to fabricate optical waveguides by two-photon absorption (TPA) processes. Particularly, the waveguides can be directly integrated on pre-configured PCB by in situ positioning the optical waveguides with respect to the mounted optoelectronic components by the TPA process. Thus, no complex packaging or assembly is necessary, and the number of process steps is significantly reduced, where the process fits ideally into the PCB fabrication process. The material properties, the TPA processing of waveguides, and the integration concept will be discussed. Recent experiments employing vertical-cavity surface-emitting lasers demonstrated data rates exceeding 6 Gbit/s