Adiabatic following and slow optical pulse propagation in rubidium vapor

Short pulses of narrow-line low-intensity dye-laser light nearly resonant with the Zeeman-split 2P1/2 esonance line (7948 A) of rubidium were observed to propagate through dilute rubidium vapor as slowly as (1/14)c. These slow pulse velocities showed that most of the energy in the propagating wave was contained by the vapor as coherent atomic excitation. The observed pulse velocities vp are in good agreement with the equation vp=dw/dk for the group velocity obtained from linear-dispersion theory. Also, the experimental results are quantitatively explained by adiabatic following, in which the pseudomoments of the atoms remain aligned along the effective field of the laser light. The adiabatic-following model allows for a direct comparison of our results with the work on self-induced transparency. For high-intensity light, adiabatic following predicts a nonlinear pulse velocity and the possibility of observing self-steepening.Peer reviewedElectrical and Computer Engineerin

Coherent excitation, incoherent excitation, and adiabatic states

Coherent excitation of an atomic excited state occurs during the propagation of near-resonant light pulses and is responsible for the induced polarization. Simultaneously, incoherent excitation occurs due to the relaxation processes described by the absorption coefficient. Here, the theory for the coherent and incoherent excitation is initially presented in terms of the traditional vector model. While a complete understanding of the two-level system is provided by the vector model, it is shown to be incomplete when the problem of directly monitoring the coherent and incoherent excitation is considered. This is because this latter problem involves more than two levels. For this more complicated multilevel problem, adiabatic states are introduced to gain further understanding. The adiabatic states are the stationary states of the atom in the presence of the near-resonant laser field; they help to explain the intimate connection between the coherent excitation and the two-photon resonance. Experimental measurements of the coherent and incoherent excitation associated with near-resonant pulse propagation in Rb vapor are presented. The double-resonance technique used a relatively strong pulsed dye laser tuned near the 5S1/2 5P1/2 transition (7948 A) of Rb to produce the coherent and incoherent excitation, and a weak, tunable cw dye laser tuned in the region of the 5P1/2 6D3/2 transition (6206 A) to monitor this excitation, In agreement with theory, the experimental results demonstrate that coherent excitation is responsible for two-photon absorption, while the incoherent excitation corresponds to one-photon absorption to the 5P1/2 state.Peer reviewedElectrical and Computer Engineerin

Absorption Bands of Alkali metals Due to the Presence of Forcign Gases

Author Institution: University of OregonPresentations without an abstract printed in the proceedings do not have an abstract (image or text) in the Knowledge Bank record

Bandes d'absorption du rubidium et du césium en présence des gaz etrangers

Des bandes d'absorption étroites et diffuses sont observées du côté des courtes longueurs d'onde du second membre de la série principale du rubidium et du césium en présence de gaz étrangers (He,Ne, A, N2 et H 2). La position et la largeur de la bande dépendent de la nature des gaz employés. L'écartement de ces bandes de la raie principale voisine croît du Ne, à N2, à He et à H2, et pour un même gaz étranger, il est plus grand dans le cas du rubidium que dans le cas du césium. L'intensité de la bande augmente avec la concentration de l'atome alcalin et aussi avec celle du gaz étranger