Given that the laser’s full potential as a tool has yet to be realized, the 21st century is set to become the century of photonics (named for the photon, or light quantum). For example, laser light – in the form of sequences of ultrashort light pulses is now elucidating the nature of quantum processes in ever greater detail, allowing researchers to characterize the incredibly fast dynamics of electrons within atoms.

Lasers have also become established in medicine, and current research trends include the quest for laser-based procedures for the early diagnosis and treatment of cancer. These efforts seek to exploit the ability of ultrashort laser pulses to identify the organic compounds (generally referred to as ‘metabolites’) present in samples of biological fluids. In principle, this makes it possible to generate a ‘molecular fingerprint’ that reflects the donor’s state of health – because the range of metabolites produced by healthy cells differs in certain ways from those synthesized in tumour cells, for example. Pulsed laser light interacts with the atoms in all these chemical compounds in highly specific ways such that particular frequencies are absorbed, depending on the structure of the molecule. Analysis of the transmitted spectrum therefore enables one to identify the molecular species that are present in a blood sample, and their concentrations. The method could one day enable doctors to detect cancers at very early stages, when they are relatively easy to treat successfully.