5. Conclusions and outlook

Nanophotonics, at the crossroads of engineering and scientific development, gives a second life to heat sources. Thermal sources are a multidisciplinary field requiring a subtle balance between thermics, electromagnetism and materials. Most of the sources developed over the last ten years or so are still laboratory objects that need to mature further before they can be integrated into systems for gas measurement, infrared camera calibration or energy applications (radiative cooling, lighting, thermophotovoltaics). At the same time, there are still a number of challenges to be met by these sources, particularly in each of the major families mentioned in the article. First of all, we still need to improve performance in terms of spectral or angular finesse – while limiting the energy lost radiatively at other wavelengths or in other directions. In addition, modulation of thermal emission...