Optical assembly using low DN/DT optical adhesive

Embodiments of an optical assembly and methods of making it are provided. The optical assembly includes a first waveguide, a second waveguide, and an optical adhesive for transmitting optical signals between the first waveguide and the second waveguide. The adhesive includes about 20% to about 60% by volume of first monomers. The first monomers have at least two acrylate or methacrylate groups. The optical adhesive also includes about 40% to about 80% by volume of second monomers. The second monomers have at least one fluorine atom and at least one acrylate or methacrylate group. The optical adhesive has a refractive index of from about 1.40 to about 1.55, and in the temperature range of about 10° C. to about 85° C., the refractive index of the optical adhesive has a thermal drift dn/dT of less than the absolute magnitude of |4×10 −4 /° C.| and the sign of that value is negative.