Nonreciprocal light propagation in a silicon photonic circuit

Optical communications and computing require on-chip nonreciprocal light propagation to isolate and stabilize different chip-scale optical components. We have designed and fabricated a metallic-silicon waveguide system in which the optical potential is modulated along the length of the waveguide such that nonreciprocal light propagation is obtained on a silicon photonic chip. Nonreciprocal light transport and one-way photonic mode conversion are demonstrated at the wavelength of 1.55 micrometers in both simulations and experiments. Our system is compatible with conventional complementary metal-oxide-semiconductor processing, providing a way to chip-scale optical isolators for optical communications and computing.     

Tolerance of parsley varieties to Orobanche

Parasitic plants infest numerous plants throughout the world depleting them of nutrients, minerals and water. Orobanche species are chlorophyll-lacking root holoparasites that cause severe damage to broad-leaved crops. Orobanche aegyptiaca and Orobanche crenata parasitize field, vegetable, fodder, flower and herb crops in the Mediterranean region. Curled parsley (Petroselinum crispum), a major crop in the dry herb industry in Israel, is highly susceptible to O. aegyptiaca and O. crenata and in infested fields suffers severe yield and quality damage. An in vitro study in polyethylene bags, greenhouse experiments in soil-filled pots and trials in a naturally Orobanche-infested field were performed in order to screen and test for differential susceptibility of parsley varieties to O. aegyptiaca and O. crenata. Results revealed that the parsley varieties Garland and Garbo were tolerant to Orobanche compared to the susceptible varieties Darki, Extra Triple and Kaderava.