A wearable therapeutic device is disclosed. An optically transmissive resin can have a surface provided with metallic films formed thereon and be employed to seal an LED chip and wires therein. Some embodiments connect to a segmented circumferential connection plate. Thus, for instance, the invention could be used to drain hoses used to drain black andor gray waste water holding tanks of recreation vehicles, motor homes, travel trailers, campers, airplanes, and boats. The residual error may manifest itself as an asymmetry in the diffraction spectra. In other embodiments, semiconductor nanocrystals are embedded within matrixes to form a nanocrystal density gradient, thereby creating an effective refractive index gradient.