Patent ID: 6925231

Claim:
An optical device having a plurality of optical waveguides and comparing at least one waveguide, which is defined by a core region having first and second sections that are series connected and are capable of transmitting light energy, the core region being surrounded by a cladding that essentially confines the light energy within the core region, the first section of the core region comprising a first length of material whose refractive index increases as temperature increases, wherein the at least one waveguide is temperature-compensating and the second section of the core region comprises a second length of material whose refractive index has a sufficient enough difference of the rate of the variation of the index with the temperature, wherein the second section has a plurality of grooves, filled with the material whose refractive index has a sufficient enough difference of the rate of the variation of the index with the temperature, that are designed in a way the effective width of the second section changes between adjacent wave-guides and where each groove of the second section has the shape of a triangle over its whole length, and the grooves of the second section have different pseudo randomize widths uniform along the lengths of the grooves.