23 research outputs found
Evanescent light-matter Interactions in Atomic Cladding Wave Guides
Alkali vapors, and in particular rubidium, are being used extensively in
several important fields of research such as slow and stored light non-linear
optics3 and quantum computation. Additionally, the technology of alkali vapors
plays a major role in realizing myriad industrial applications including for
example atomic clocks magentometers8 and optical frequency stabilization.
Lately, there is a growing effort towards miniaturizing traditional
centimeter-size alkali vapor cells. Owing to the significant reduction in
device dimensions, light matter interactions are greatly enhanced, enabling new
functionalities due to the low power threshold needed for non-linear
interactions. Here, taking advantage of the mature Complimentary
Metal-Oxide-Semiconductor (CMOS) compatible platform of silicon photonics, we
construct an efficient and flexible platform for tailored light vapor
interactions on a chip. Specifically, we demonstrate light matter interactions
in an atomic cladding wave guide (ACWG), consisting of CMOS compatible silicon
nitride nano wave-guide core with a Rubidium (Rb) vapor cladding. We observe
the highly efficient interaction of the electromagnetic guided mode with the
thermal Rb cladding. The nature of such interactions is explained by a model
which predicts the transmission spectrum of the system taking into account
Doppler and transit time broadening. We show, that due to the high confinement
of the optical mode (with a mode area of 0.3{\lambda}2), the Rb absorption
saturates at powers in the nW regime.Comment: 10 Pages 4 Figures. 1 Supplementar
P-fimbriae in the presence of anti-PapA antibodies : new insight of antibodies action against pathogens
Uropathogenic strains of Escherichia coli establish urinary tract infections by attaching to host epithelial cells using adhesive organelles called fimbriae. Fimbriae are helix-like structures with a remarkable adaptability, offering safeguarding for bacteria exposed to changing fluid forces in the urinary tract. We challenged this property of P-fimbriae by cross-linking their subunits with shaft-specific antibodies and measuring the corresponding force response at a single organelle level. Our data show compromised extension and rewinding of P-fimbriae in the presence of antibodies and reduced fimbrial elasticity, which are important properties of fimbriae contributing to the ability of bacteria to cause urinary tract infections. The reduced elasticity found by cross-linking fimbrial subunits could thus be another assignment for antibodies; in addition to marking bacteria as foreign, antibodies physically compromise fimbrial function. We suggest that our assay and results will be a starting point for further investigations aimed at inhibiting sustained bacterial adhesion by antibodies