Embodiments of spectral filters with dye-impregnated nano-spheres are described herein. Other embodiments may be described and claimed. In some embodiments, a spectral filter comprises a host material that includes a plurality of nano-particles embedded within. The particles include a dye having an absorption band of wavelengths and have a size selected to resonate at a range of wavelengths that is within the absorption band. The particles may be selected to resonate in either a plasmon mode or a whispering-gallery mode.