Patent ID: 8644124

Claim:
A waveguide comprising: a first cladding layer, the first cladding layer having an index of refraction, n 3 ; an assist layer, the assist layer having an index of refraction, n 2 , and the assist layer comprising ASi x O y , wherein A is selected from: Ta, Ti, Nb, Hf, Zr, and Y, x is from about 0.5 to about 2.0, y is from about 3.5 to about 6.5, and the atomic ratio of A/A+Si in ASi x O y is from about 0.2 to about 0.7; and a core layer, the core layer having an index of refraction, n 1 , wherein n 1 is greater than n 2 and n 3 , and n 2 is greater than n 3 .