As a fundamental mystery, light has inspired scientists for centuries. Across the electromagnetic spectrum, from long-wavelength infrared radiation through X-rays and high-energy γ-rays, light is an indispensable tool for probing matter in atomic and solid-state physics and astrophysics, as well as in chemistry, biology and medicine. Yet research into the fundamental nature of light and its potential uses remains among the most vibrant areas of science.
In the decade to come, optics research and applications will rapidly progress along several lines. As illustrated recently, promising avenues include the fundamental exploration of how light interacts with matter, the engineering of new materials with hitherto unknown optical properties, and efforts to put light to use in powerful new schemes for information processing and communication.
The movement of electrons in atoms or molecules, or inside bulk materials, underlies the properties of all matter, including the chemistry that sustains life. Electronic events take place on a short time scale of around 10–18 seconds (1 as)1, and it is only recently that physicists have devised laser light sources that come close to being able to take snapshots this quickly2. These laser pulses make ‘light-wave electronics’ possible, not only to study electron motion in precise detail, but also to steer individual electrons during chemical reactions so as to form desired chemical bonds. Short pulses of light with tailored properties have also been used to manipulate the collective quantum behaviour of many electrons in complex materials.
The interaction of intense X-ray laser beams with atomic nuclei has also opened up the new field of nuclear quantum optics3. An intense laser field might cause an electron to be released from an atom and then to collide again with that atom with high energy. This effect mimics the action of a high-energy particle accelerator and might soon be used to probe the physics of the atomic nucleus.