ABSTRACT
Integrated silicon nitride waveguides of 100â nm height can achieve ultralow propagation losses below 0.1â dB/cm at the 1550â nm wavelength band but lack the scattering strength to form efficient grating couplers. An enhanced grating coupler design based on an amorphous silicon layer on top of silicon nitride is proposed and demonstrated to improve the directionality of the coupler. The fabrication process is optimized for a self-alignment process between the amorphous silicon and silicon nitride layers without increasing waveguide losses. Experimental coupling losses of 5â dB and a 3â dB bandwidth of 75â nm are achieved with both regular and focusing designs.
ABSTRACT
Natural and experimental poisonings by Cestrum laevigatum are described in goats. Histologically, livers had marked centrolobular and midzonal coagulative necrosis and hemorrhage. Spontaneous toxicosis by this plant in goats has not been previously reported.