Diode lasers and spectroscopy

A wide variety of new laser applications would be feasible if we had tunable, single-frequency laser sources that were compact, lightweight and operated with low power consumption. Some of these applications include: atmospheric and process monitoring, atomic and molecular spectroscopy, ultrasensitive detection and analytic applications, lidar and ranging, and new optical frequency/length references. Semiconductor diode lasers can now meet these challenges in many cases, particularly for laboratory experiments. Extension of this technology to higher powers, extended wavelength coverage, and transportable instrumentation is on the near term horizon. For some time now it has been possible to construct single-frequency tunable diode laser systems that operate at many wavelengths in the red and near IR spectral region. Even commercial tunable diode laser systems are now readily available at most of the wavelengths accessible with commercial semiconductor lasers chips.