A waveguide, the waveguide having the device and disk drive

Waveguides that include a top cladding layer made of a material having an index of refraction n 4 ; a core bilayer structure, the core bilayer structure including a lower index core layer having an index of refraction n 3 ; and a higher index core layer having an index of refraction n 1 , wherein the higher index core layer includes TiO 2 and one or more than one of Nb 2 O 5 , CeO 2 , Ta 2 O 5 , ZrO 2 , HfO 2 , Y 2 O 3 , Sc 2 O 3 , MgO, Al 2 O 3 and SiO 2 , wherein the lower index core layer is adjacent the higher index core layer; a bottom cladding layer made of a material having an index of refraction n 2 , wherein the waveguide is configured with the higher index core layer of the core bilayer structure adjacent the top cladding layer and the lower index core layer of the core bilayer structure adjacent the bottom cladding layer, and wherein n 4 is less than n 3 and n 1 , and n 2 is less than n 3 and n 1 .