Extended length embedded bragg grating manufacturing method and

Abstract

An arrangement for forming an extended length light redirecting embedded grating in an elongated solid material optical waveguide includes a source that directs a coherent light beam of a frequency in the ultraviolet range in a primary path transversely toward the waveguide. A section of a diffraction grating extends through the primary path at a spacing from the waveguide, and the diffraction grating has a dimension normal to the primary path that exceeds the corresponding dimension of the primary path. Relative movement is effectuated between the waveguide and diffraction grating in unison, and the primary path, so that the light beam is diffracted at the diffraction grating into two mutually frequency shifted partial light beams propagating in diverging secondary paths. The partial light beams are caused to travel toward a shared location of the waveguide where they form an interference pattern that moves longitudinally of the waveguide but respective high intensity fringes of which extend through the waveguide at respective positions that are stationary relative to the waveguide to effect refractive index changes at such positions along an extended length of the waveguide.