Trapping the light fantastic

摘要

Storing or confining light without absorbing it is of great importance for both science and technology. A device or system for trapping light is known as an optical resonator, and its most basic component is some kind of reflecting surface or region - a mirror in the general sense of the word. The most common type of mirror, a glass surface covered with a thin metal layer, has been around for two millennia, and mirrors of this type are crucial components of many optical systems. However, metal-based mirrors do absorb light to some degree. So, in modern optics research, scientists have developed many types of reflecting surfaces and resonators based on other principles. Given the tremendous and long-standing emphasis that optics places on trapping light, it is surprising that a substantially new type of mirror could still be discovered, but that is precisely what Hsu et al. have done (page 188 of this issue).