4. Conclusion

As we said in the introduction, the concept of metamaterials is both very old and very recent. In electromagnetics, the notion of left-handed materials only took shape in 2001. Despite this, the development of studies is exponential, even if it is still relatively modest in France. Hopes are relatively high for microwaves, as this concept offers the prospect of developing original applications (ultra-compact smart antennas, phase shifters, filters, etc.). In this field, the use of metamaterials may gradually become a technique like any other, with specific applications that would otherwise be impossible to achieve. In optics, and also in the intermediate range of terahertz frequencies, progress has been slower because the technology involved is more delicate. But recent technological developments around large-scale flexible structures and three-dimensional nanometric structures in optics...