Patent ID: 6741769
Filing Date: 2004-05-25
Classification: G02F

Abstract:
An optical device comprising:a substrate having at least one light-guiding core and cladding material surrounding the core; a cladding-modifying element disposed alongside, at least in part, a portion of the light-guiding core, the cladding-modifying element being formed of a material different to the cladding material so that the refractive index difference between the material of the cladding-modifying element and the cladding material is dependent upon the temperature of the cladding-modifying element, and the cladding-modifying element being disposed with respect to the core so that in operating conditions in which the refractive index of the cladding-modifying element is different to the refractive index of the cladding, light passing along the core is coupled by evanescent coupling out of the core and into the cladding-modifying element; and a heating and/or cooling arrangement for altering the temperature of the cladding-modifying element; and wherein the portion of the core is narrowed.