Various embodiments of a hermetically-sealed package and a method of forming such package are disclosed. The package can include a housing having an inner surface and an outer surface, and a non-conductive substrate hermetically sealed to the housing. The package can also include a light source disposed on a first major surface of the substrate and adapted to emit light through the first and second major surfaces of the substrate, and a detector disposed on the first major surface of the substrate and adapted to detect the light emitted by the light source.