Search

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.

We present a study of a two-photon double-resonance transition in cold cesium atoms in a magneto-optic trap. A closed five-level density matrix model of the system is developed to characterize the double-resonance Autler–Townes-split absorption line shape. Comparing this model with experimental spectra, we gain insight into the dominant process involved in trapping atoms, in particular, the importance of the interference of the six trapping laser beams. This system is used to probe transient effects in the trap as well as collective effects of the trapped atom cloud resulting from the intentional misalignment of the trapping beams.

Transitions between excited states of laser-cooled and laser-trapped rubidium and cesium atoms are probed by use of fiber and diode lasers. High-resolution Doppler-free spectra are detected by observation of the absorption and fluorescence of light from the intermediate level of two-step cascade systems. The optical double-resonance spectra show Autler-Townes splitting in the weak probe limit and more complicated spectra for a strongly coupled three-level system.