On the theory of double optical resonance

Robert Serber

D P O'Brien, S. Swain

The authors examine the theory of optical double resonance using two lasers whose finite linewidths are produced by the process of phase-diffusion. Their lineshapes, which are nonLorentzian, are characterised by a bandwidth B and a cut off C. The authors are concerned with obtaining an analytic theory; they achieve this by assuming the ratio B/C to be small and work to first order in B/C (although the method can be extended to higher order in B/C). They obtain analytic expressions for the optical double resonance spectrum and discuss the results of recent experiments by Hogan et al. (1978) and Nitz et al. (1981) in which it was found that the asymmetry of the peaks in the optical double resonance spectrum changed with detuning. It is found that a qualitative understanding can be achieved but that a full quantitative comparison is not yet possible.

Nikolay N. Bogolubov, Tran Quang, A.S. Shumovsky

Alan Corney

Michio Takami

The theory of optical-microwave double resonance is extended to the case of the off-resonant optical field. Line shapes for fixed optical and variable microwave frequencies are calculated under various conditions by the density matrix method. Analytical expressions are given for small microwave or small optical saturation. When the off-resonance is much greater than the Doppler width of the optical transition, optical Stark effect and optical-microwave two-photon transition are the principal effects. When the signal is observed as a variation of microwave absorption, the former effect is much stronger than the latter. When the signal is detected optically, the two-photon and the stepwise transitions for small microwave saturation are the effects with the same order of magnitude, while the optical Stark effect is a secondary effect. The line shapes are also calculated numerically for arbitrary microwave and optical saturation.