A semiconductor device includes: a transistor layer including components of at least one transistor, a waveguide having a long axis extending in a first direction, and an alpha interconnection layer over the waveguide; a stack of metallization layers over the transistor layer, the stack including one or more beta interconnection layers interposed between corresponding pairs of neighboring ones of the metallization layers; and a heater in the alpha interconnection layer or in one of the one or more beta interconnection layers; and wherein, relative to a second direction substantially perpendicular to the first direction, the heater substantially overlaps at least a portion of the waveguide.