scholarly journals Modification of Level Dependent ASE-Signal Beat Noise by Optical and Electrical Filtering in Optically Preamplified Direct Detection Receivers

2018 ◽  
Vol 10 (1) ◽  
pp. 1-16 ◽  
Author(s):  
J. Witzens ◽  
J. Muller ◽  
A. Moscoso-Martir
Keyword(s):  
Direct Detection ◽  
Beat Noise

61 Gbits/s direct-detection optical OFDM based on blockwise signal phase switching with signal-to-signal beat noise cancellation

2013 ◽  
Vol 38 (14) ◽  
pp. 2614 ◽  
Author(s):  
An Li ◽  
Di Che ◽  
Xi Chen ◽  
Qian Hu ◽  
Yifei Wang ◽  
...  
Keyword(s):  
Direct Detection ◽  
Noise Cancellation ◽  
Signal Phase ◽  
Phase Switching ◽  
Beat Noise ◽  
Optical Ofdm

Detection and Characterization of earth-like Planets

1997 ◽  
Vol 161 ◽  
pp. 299-311 ◽  
Author(s):  
Jean Marie Mariotti ◽  
Alain Léger ◽  
Bertrand Mennesson ◽  
Marc Ollivier
Keyword(s):  
Direct Detection ◽  
Contrast Ratio ◽  
Angular Size ◽  
Physical Nature ◽  
Major Axis ◽  
Infrared Emission ◽  
Space Technology ◽  
Semi Major Axis ◽  
Earth Like Planets ◽  
Visible Wavelengths

AbstractIndirect methods of detection of exo-planets (by radial velocity, astrometry, occultations,...) have revealed recently the first cases of exo-planets, and will in the near future expand our knowledge of these systems. They will provide statistical informations on the dynamical parameters: semi-major axis, eccentricities, inclinations,... But the physical nature of these planets will remain mostly unknown. Only for the larger ones (exo-Jupiters), an estimate of the mass will be accessible. To characterize in more details Earth-like exo-planets, direct detection (i.e., direct observation of photons from the planet) is required. This is a much more challenging observational program. The exo-planets are extremely faint with respect to their star: the contrast ratio is about 10−10at visible wavelengths. Also the angular size of the apparent orbit is small, typically 0.1 second of arc. While the first point calls for observations in the infrared (where the contrast goes up to 10−7) and with a coronograph, the latter implies using an interferometer. Several space projects combining these techniques have been recently proposed. They aim at surveying a few hundreds of nearby single solar-like stars in search for Earth-like planets, and at performing a low resolution spectroscopic analysis of their infrared emission in order to reveal the presence in the atmosphere of the planet of CO H2O and O3. The latter is a good tracer of the presence of oxygen which could be, like on our Earth, released by biological activity. Although extremely ambitious, these projects could be realized using space technology either already available or in development for others missions. They could be built and launched during the first decades on the next century.

A novel enzyme immunoassay for the direct detection of H. pylori antigens in stool

2001 ◽  
Vol 120 (5) ◽  
pp. A492-A493 ◽  
Author(s):  
E HAINDL ◽  
H BENESCH ◽  
A FINCK ◽  
V MUEHISTEIN ◽  
A LEODOLTER ◽  
...  
Keyword(s):  
Enzyme Immunoassay ◽  
Direct Detection ◽  
H Pylori
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