A method of fabricating an integrated circuit having a window therein for transmitting optical energy to and/or from an optically active area of the underlying die includes depositing a quantity of an uncured optically transmissive material on the die portion of a integrated circuit preform, placing the window on the surface of the uncured optically transmissive material, placing the so-assembled components into a curing mold having surfaces thereof that establish the dimensional relationship and/or alignment between the window and the optically active area or areas of the underlying die, and curing the optically transmissive material to establish the dimensional relationship and/or alignment between the window and the optically active area or areas of the underlying die, and, thereafter, applying a conventional encapsulating material thereto to form the final package.