Comparison of two types of 60 GHz photonic millimeter-wave generation and distribution of a 3 Gb/s OFDM signal

International audienceWe demonstrate and compare experimentally two set-ups achieving very high data rate (3 Gbps) wireless transmission in the 60 GHz window, both using Radio-over-Fiber (RoF) for reach extension with OFDM signal compliant to the IEEE 802.15.3.c pre-standard

Transmission Quality Measurement of Two Types of 60 GHz Millimeter-Wave Generation and Distribution Systems

International audienceIn this paper, we demonstrate and compare experimentally two techniques achieving very high-data-rates (> 1 Gb/s) wireless transmission in the 60 GHz window using radio over fiber (RoF) for reach extension. The first RoF link is based on a 10 GHz vertical-cavity surface-emitting laser and uses a multimode fiber. The radio signal is transported on an intermediate frequency of 4.5 GHz and electrically upconverted to 60 GHz after the optical link. The second uses an optical frequency upconversion from 4.5 to 60 GHz by direct modulation of a mode-locked Fabry-PEacuterot laser whose self-pulsating frequency is 54.8 GHz before transmission over a single-mode fiber. For both techniques, two different types of modulation were tested. The first one was an on-off keying at 1.5 Gb/s and the second one was an orthogonal frequency-division multiplexing-QPSK signal compliant to the IEEE 802.15.3.c prestandard (3.03 Gb/s). Radio propagation performance is also reported

A TOMOGRAPHIC STUDY OF MEASUREMENTS IN A V-SHAPED H-2-AIR FLAME AND A LAGRANGIAN INTERPRETATION OF THE TURBULENT FLAME BRUSH EVOLUTION

Goix, p paranthoen, p trinite, mFlamelet structures and the evolution of flame brush thickness of H2-air V-shaped flames are studied by laser tomography. The flames have a lean equivalence ratio of φ = 0.2. The flow velocity is 5 m/s and the turbulence intensity at the flame holder generated by a grid varies from 3.5% to 5%. The flames are within the wrinkled laminar flame regime. A sheet of pulsed laser light (Ruby rod) of 75 × 80 mm illuminates an oil aerosol seeded in the H2-air flow, and the instantaneous flame structures are obtained when the oil droplets evaporate on passage through the flame front. The flames are imaged onto a CCD camera. The camera is interfaced with a matrix memory of 512 × 512 pixels with a dynamic range of 256 gray scales, and the tomographic records are analyzed by a digital image processing technique. The gray level corresponding to the flame front is determined by a filtering and thresholding operation. The first and second moments and correlations of flame front positions are deduced from the measurement of 240 instantaneous, statistically independent flames. The results show that the turbulence characteristics and equivalence ratio have an important effect on the shape and the dynamics of the flame. In particular, the growth of turbulence flame brush, δT, is linear for a distance that can be correlated with the Lagrangian time scale of the turbulence. Furthermore, the slope of this evolution is proportional to the turbulence intensity at the flame holder. The linear growth is consistent with results observed by others for wrinkled laminar flames. The changes in the local flame surface area with downstream distance are estimated by the length of the flamelet segment within a vertical window of 10 pixels. The flame area increases are found to be accompanied by increases in the mean flame angle as shown by the width of the burned zone. These results confirm that the wrinkled laminar flame model is valid for the flames studied here. The flame front fluctuation results are interpreted using a Lagrangian diffusion model developed by Karlovitz. From this model, the value of the rms displacement of a flame element is calculated based on the approach flow turbulence characteristics (in comparison with the propagation speed of the flame fronts). Model predictions and experimental results are in good agreement. This indicates that the concept of a diffusion process for describing flame movement is important for study of premixed turbulent flame propagation

Ultra-High-Speed 2:1 Digital Selector and Plasmonic Modulator IM/DD Transmitter Operating at 222 GBaud for Intra-Datacenter Applications

We demonstrate a 222 GBd on-off-keying transmitter in a short-reach intra-datacenter scenario with direct detection after 120 m of standard single mode fiber. The system operates at net-data rates of >200 Gb/s OOK for transmission distances of a few meters, and >177 Gb/s over 120 m, limited by chromatic dispersion in the standard single mode fiber. The high symbol rate transmitter is enabled by a high-bandwidth plasmonic-organic hybrid Mach–Zehnder modulator on the silicon photonic platform that is ribbon-bonded to an InP DHBT 2:1 digital multiplexing selector. Requiring no driving RF amplifiers, the selector directly drives the modulator with a differential output voltage of 622 mV pp measured across a 50 Ω resistor. The transmitter assembly occupies a footprint of less than 1.5 mm × 2.1 mm.ISSN:0733-8724ISSN:1558-221