Losses in left-handed materials

Interest in negative refractive index, or left-handed (LH) materials, has escalated rapidly over the last few years and it now appears that useful LH materials may be realizable in the microwave region. However there is also considerable interest in LH materials for infrared and visible applications. The purpose of this paper is to explore the limitations of LH materials at short wavelengths due to inherent losses. Our conclusions are that it may be quite difficult to achieve useful LH materials at wavelengths less than about 10 microns using current approaches.