Ultra low power consumption operation of SOA assisted extended reach EADFB laser (AXEL)
We propose a novel structure to reduce the power consumption and extend the transmission distance of a 10-Gbit/s, 1.55-µm EADFB laser. The power consumption is reduced by 1/2 and the transmission distance is extended.
An SOA-integrated EADFB laser for enhancement of modulated light output power and extension of transmission distances
Electro-absorption modulator (EAM) integrated distributed feedback (EADFB) laser are widely used for 10-, 40- and over 40-km optical communications. In a certain power dissipation condition, there is intrinsic difficulty in increasing the modulated light output power of EADFB lasers, because large insertion loss of the EAM deteriorates the power conversion efficiency. In this study, we investigated an SOA integrated with a EADFB laser to improve the power conversion efficiency of the EADFB laser. The device is called an SOA assisted extended reach EADFB laser, or AXEL for short. For a transmission with a 1.3-μm wavelength, the transmission distance was limited to 40 km because of the large fiber loss of 0.3 dB/km. To overcome this kind of transmission distance limit, we demonstrated a 1.3-μm AXEL with significantly increased power conversion efficiency. In addition, a 25-Gbit/s 80-km transmission by using AXEL and APD-ROSA was firstly achieved beyond the limitation of transmission distance. In contrast, with respect to an L-band wavelength range, a large chromatic dispersion severely limits the transmission distance. Then, we also investigated the AXEL with 1.57 μm wavelength range, and found that the SOA can operate as both optical booster and chirp compensator. Furthermore, the extension of 10-Gbit/s transmission to 80-km and enhancement of modulated light output power to 9.0 dBm were simultaneously achieved by taking advantages of its chirp compensation effect and high power conversion efficiency. The presented results indicate that the AXEL is an attractive candidate for a high-efficiency modulated light source with any wavelength range.
The unfolded universe of elementary particles. A geometric explanation of the standard model structure
We propose a geometric explanation of the standard model of Glashow, Weinberg and Salam for the known elementary particles. Our model is a generic Quantum Field Theory in dimension four, obtained by developing along a Lorentz sub-manifold the lagrangian of Einstein and Dirac in dimension twelve. The main mechanism which gives birth to the standard model is a certain gauge fixing of triality, which permits to identify the multiplicity of fermions, as seen from the four dimensional world, with the eight unseen dimensions of the generating universe. In this way we get the known tables of particles, explaining the series of fermions and the gauge bosons. We suggest that the Higgs field dynamics could appear through a bosonization of the right handed neutrino and correspond to a displacement in the unseen dimensions. We also propose hypotheses for dark matter, and perhaps dark energy. Then we suggest predictions to go beyond the standard model.