A system for forming a laser-sustained plasma includes a gas containment element, an illumination source configured to generate pump illumination, and a collector element. The gas containment element is configured to contain a volume of a gas mixture. The collector element is configured to focus the pump illumination from the pumping source into the volume of the gas mixture contained within the gas containment element in order to generate a plasma within the volume of the gas mixture that emits broadband radiation. The gas mixture filters one or more selected wavelengths of radiation emitted by the plasma.