A linearized thermal and optical model of an optical integrated circuit can be used to temperature-stabilize one or more optical elements of the circuit using active temperature regulation. A primary winding having P turns is coupled with the first and second magnetic cores, a measurement winding having M turns is coupled with the first and second magnetic cores so that current in the primary winding induces current in the measurement winding, and a sense winding having S turns is coupled with the second magnetic core. The coating material contains a solvent of ethylene glycol, propylene glycol ether, water and an alcohol having 1-3 carbon atoms. The first and second portions partially define a fluid communication path between the first and second configurations.