Embodiments of apparatus for providing radiant energy in the form of electromagnetic radiation are provided herein. In some embodiments a radiation source for electromagnetic radiation includes a tubular body formed from a material transparent to electromagnetic radiation; a filament disposed within the tubular body; and a reflective coating disposed on a portion of the tubular body to form a reflective portion, wherein the reflective portion is configured to minimize reflection of electromagnetic radiation emanating from the filament during use back to the filament.