Laser technology—the ability to generate intense and coherent light with controllable properties—is one of the most significant enabling achievements of 20th-century science. Because atoms interact through the electromagnetic force, researchers can probe—and in some cases control—the properties and dynamics of atomic, molecular, or condensed matter systems with unprecedented precision simply by applying external, controlled electromagnetic fields.
In recent years, nonlinear-optical techniques that convert one frequency of light to another have played an increasingly pivotal role in that technology—a role second in significance only to that of the laser itself. Optical frequency doubling or parametric amplification, for instance, converts laser light into coherent radiation tunable over the near-IR, visible, and near-UV regions of the spectrum. Recent years have also seen the development of ultrashort-pulse technologies. The uncertainty principle ΔEΔt ≥ ħ/2 dictates that a very short pulse of light must have broad spectral bandwidth. However, generating...
