Overview

The organic dye laser has found many applications in scientific research because of its unusual flexibility. Its output wavelength can be tuned from the near-ultraviolet into the near-infrared; the use of frequency-doubling crystals can extend emission further into the ultraviolet. Dye lasers can be adjusted to operate over an extremely narrow spectral bandwidth, producing ultrapure light for studies of optical properties of materials in very narrow wavelength regions. They also can produce ultrashort pulses, with durations much shorter than a picosecond.

This versatility comes at a cost in complexity. Individual dyes can emit light at a broader range of wavelengths than other lasers, but a range that is still narrow compared with the entire visible spectrum. Tuning wavelength across the entire visible range requires several changes of dye. The dyes degrade, and because they must be dissolved in a solvent, require a complex liquid-handling system. They require excitation with a separate source of intense light, another laser or a flashlamp, which adds to the cost and complexity, although the choice of pump sources does give some added flexibility. Complex optics are needed to produce either ultranarrow-linewidth output or picosecond pulses, and the two cannot be produced simultaneously. Designers of dye lasers have made great strides to build systems which can be used readily by biologists, chemists, and others whose specialties are far from laser technology, but dye lasers are still more scientific instruments than industrial tools.

Dye lasers have made vital contributions to spectroscopy. It was not long after...