Combined selective emitter and filter for high performance incandescent lighting

The efficiency of incandescent light bulbs (ILBs) is inherently low due to the dominant emission at infrared wavelengths, diminishing its popularity today. ILBs with cold-side filters that transmit visible light but reflect infrared radiation back to the filament can surpass the efficiency of state-of-the-art light-emitting diodes (LEDs). However, practical challenges such as imperfect geometrical alignment (view factor) between the filament and cold-side filters can limit the maximum achievable efficiency and make the use of cold-side filters ineffective. In this work, we show that by combining a cold-side optical filter with a selective emitter, the effect of the imperfect view factor between the filament and filter on the system efficiency can be minimized. We experimentally and theoretically demonstrate energy savings of up to 67% compared to a bare tungsten emitter at 2000 K, representing a 34% improvement over a bare tungsten filament with a filter. Our work suggests that this approach can be competitive with LEDs in both luminous efficiency and color rendering index (CRI) when using selective emitters and filters already demonstrated in the literature, thus paving the way for next-generation high-efficiency ILBs.