Evaluation of a discrete 4-PAM optical link for future automotive networks

A comparative study is presented between NRZ and 4-PAM to investigate the feasibility of Gigabit transmission in automotive optical networks. The system utilizes a SI-PCS fiber and an 850 nm VCSEL as transmitter. Laser driver and receiver are realized with discrete transistors at board level. Eye diagram measurements reveal that 4-PAM outperforms NRZ using 1m and 6m of fiber. Bitrates of 2 Gb/s are achieved at a BER ≤ 100000. Covering longer distances shows that SI-PCS introduces severe dispersion. Therefore, GI-PCS fiber is suggested as optical link for future automotive networks

40 Gb/s PAM-4 transmitter IC for long-wavelength VCSEL links

Conventional 850 nm multimode fiber links deployed in warehouse-scale data centers will be limited by modal dispersion beyond 10 Gb/s when covering distances up to 1 km. This can be resolved by opting for a single-mode fiber (SMF), but typically requires the use of power-hungry edge-emitting lasers. We investigate the feasibility of a high-efficiency SMF link by reporting a 0.13 mu m SiGe BiCMOS laser diode driver optimized for long-wavelength vertical-cavity surface-emitting lasers (VCSELs). Bit-error rate experiments at 28 and 40 Gb/s up to 1 km of SMF reveal that four-level pulse amplitude modulation can compete with non-return-to-zero in terms of energy efficiency and scalability. With 9.4 pJ/b, the presented transmitter paves the way for VCSEL-based SMF links in data centers

Demystifying network slicing : from theory to practice

C

DSP-free and real-time NRZ transmission of 50Gb/s over 15km SSMF and 64Gb/s back-to-back with a 1.3um VCSEL

We demonstrate and analyze 50 Gb/s non-return-to-zero (NRZ) transmission over 15 km of standard single-mode fiber (SSMF), 60-Gb/s NRZ transmission over 5 km of SSMF and up to 64-Gb/s NRZ back-to-back using a directly modulated short-cavity long-wavelength single-mode vertical-cavity surface-emitting laser (VCSEL) emitting at 1326 nm. Owing to an analog 6-tap transmit feedforward equalizer, the link can operate without digital signal processing. In all three cases, real-time bit error ratio measurements below the 7% overhead hard-decision forward error correction threshold are demonstrated when transmitting a pseudorandom bit sequence with a period of 2(7) - 1 bits. In addition, we analyze the interplay between the residual fiber chromatic dispersion at the operating wavelength of the VCSEL and the chirp due to direct modulation. These results demonstrate how O-band, short-cavity long-wavelength single-mode VCSELs can be used in intradata center networks, as well as in interdata center networks at reaches below 15 km

Fine-scale mapping of vector habitats using very high resolution satellite imagery : a liver fluke case-study

The visualization of vector occurrence in space and time is an important aspect of studying vector-borne diseases. Detailed maps of possible vector habitats provide valuable information for the prediction of infection risk zones but are currently lacking for most parts of the world. Nonetheless, monitoring vector habitats from the finest scales up to farm level is of key importance to refine currently existing broad-scale infection risk models. Using Fasciola hepatica, a parasite liver fluke as a case in point, this study illustrates the potential of very high resolution (VHR) optical satellite imagery to efficiently and semi-automatically detect detailed vector habitats. A WorldView2 satellite image capable of <5m resolution was acquired in the spring of 2013 for the area around Bruges, Belgium, a region where dairy farms suffer from liver fluke infections transmitted by freshwater snails. The vector thrives in small water bodies (SWBs), such as ponds, ditches and other humid areas consisting of open water, aquatic vegetation and/or inundated grass. These water bodies can be as small as a few m(2) and are most often not present on existing land cover maps because of their small size. We present a classification procedure based on object-based image analysis (OBIA) that proved valuable to detect SWBs at a fine scale in an operational and semi-automated way. The classification results were compared to field and other reference data such as existing broad-scale maps and expert knowledge. Overall, the SWB detection accuracy reached up to 87%. The resulting fine-scale SWB map can be used as input for spatial distribution modelling of the liver fluke snail vector to enable development of improved infection risk mapping and management advice adapted to specific, local farm situations