Diode lasers for frequency standards and precision spectroscopy

As they apply to frequency standards and precision spectroscopy the characteristics and technology of tunable diode lasers are briefly reviewed. It is now possible to use nonlinear optical techniques and high quality diode lasers to extend the useful wavelength coverage of semiconductor lasers into the UV, the IR and even millimeter-wave spectral regions. Progress in developing an all diode-laser system for cooling, trapping and precision spectroscopy of calcium is discussed. New measurements indicated that two-stage optical cooling of calcium may be feasible; this should improve the accuracy of the 657 nm optical wavelength/frequency reference.