No abstract

No abstract

A diffraction grating structure for coupling light into or out of a high refractive index waveguide layer on a carrier substrate is formed by irradiating the carrier substrate and/or the layer with UV laser light that is subject to simultaneous, spatially periodic intensity modulation. The modulation may be achieved, for example, by a biprism. The modulated UV light has the effect of periodically modulating the local refractive index of the waveguide layer or of the surface of the substrate to form the diffraction grating.

No abstract

The phenomenon colloquially known as a fiber fuse occurs when an optical fiber carrying high power is damaged or in some way abused. Beginning at the damage site a brilliant, highly visible plasmalike disturbance propagates back toward the optical source at speeds ranging from 0.3 to approximately 3 m/s, leaving in its wake a trail of bubbles and voids. We suggest that the bubble tracks in fused fibers are the result of a classic Rayleigh instability that is due to capillary effects in the molten silica that surrounds the vaporized fiber core. We report measurements of the bubble distribution and the collapse time that are consistent with this contention.