An optical broadband emitter and the method of making such a broadband emitter are described. Intermixing of closely coupled multiple quantum wells, especially carrier tunneled coupled quantum wells, is described using nano-imprinting of a gel like dielectric layer such as a sol-gel derived SiO.sub.2 layer into multiple stepped or graded sections to form intermixing cap regions of different thickness. A thermal annealing process is performed to condense the SiO.sub.2 intermixing cap and induce intermixing. A superluminescent diode is described having multiple electrodes deposited over multiple sections of different bandgaps in which each individual electrode can be either forward or reverse biased to different degrees such that each diode section can individually function as a sub-band spontaneous emitter, an amplifier/attenuator, a photon-absorber, a transparent waveguide, or a photodetector/optical power monitor.