DIODE-LASER-NOISE-BASED SPECTROSCOPY OF ALLOWED AND CROSSOVER RESONANCES

This paper analyses the extraction of spectroscopic information on an atom via use of held fluctuations in a diode laser, wherein the statis tics of diode-laser radiation are modeled by a phase-diffusion process . Using Monte Carlo methods, we solve density-matrix equations for a t hree-level V system, driven by this fluctuating held, tuned approximat ely to the two allowed transitions. The model is very general and allo ws us to incorporate arbitrary field strengths and bandwidths. We sugg est two different signal detection schemes, each of which provides ins ight into different aspects of the energy-level structure in an atomic sample. Specifically, if intensity fluctuations in the field radiated from the sample are spectrally analyzed, via a homodyne technique, on e can isolate contributions that are linear and quadratic in the radia ted held, and these reveal resonances at the allowed transition freque ncies of the atom. If we employ direct detection instead of the homody ne method, then the crossover transition is also revealed in the signa l. The strengths of these resonances are very sensitive to the bandwid th of the field fluctuations, as well as the details of the held stati stics. We also discuss the role of Stark shifts at higher intensities.