Resonance Induced in an Effective Field by Modulated Light

Krystyna Kolwas

Philippe Lalanne

Arup Neogi

We investigate the effect of an induced sum-frequency signal on the transient modulation of interband-resonant probe light by a train of intersubband-resonant coupling light pulses in undoped quantum wells. The origin of the generated sum-frequency signal lies in the asymmetry of the three-level quantum well structure. The modulation characteristics are found to be significantly affected in the presence of a strong sum-frequency signal that builds up proportionately to the input probe field.

John N. Dodd, George William Series, Martin John Taylor

Abstract This work is an experimental study of the modulation which has been found in resonance radiation when the fluorescing vapour is subjected to static and radio-frequency magnetic fields, as in the double resonance experiment of Brossel & Bitter. The particular example chosen for study in this work also was the resonance line λ 2537 Å of mercury. The experimental observations are compared with the predictions of a theoretical treatment which has already been published. The phenomenon was studied under a variety of geometrical configurations. When the polarization of the exciting light allowed excitation to only one excited state (a component of a Zeeman multiplet), the depth of modulation was found to depend on the closeness to resonance of the frequency, ω0, of the radio-frequency field to the Larmor precessional frequency, ω = γH , in the static field H. When the polarization of the exciting light allowed excitation to more than one component of the multiplet, resonance effects were found in the depth of modulation and in the mean intensity of the fluorescent light at fields where the applied frequency was equal, not to the Larmor frequency alone, but to combinations of the Larmor frequency with the nutational frequency. From a quantum-mechanical point of view, these new phenomena are related to the interference effects which are found in resonance fluorescence when there is degeneracy between excited states: in the present case the degeneracy is induced by the radio-frequency field. The ease with which the geometrical conditions could be altered allowed the theory to be tested in considerable detail without quantitative assessment of the resonance line contours: nevertheless, a quantitative study was made of one particular feature. The predictions of the theory were confirmed at all points where they were tested.

George William Series

Bo Fang, Lei Xu, Jie Wang +2 more

In this paper, we reviewed the theoretical and experimental studies on the manipulation of the group delay of light based on the transverse phase modulation effect induced by a Gaussian beam. We introduced the basic theory of slow and fast lights in a thin nonlinear material based on the transverse phase modulation effect. We introduced a simple but effective technique to actively and chromatically control the group velocity of light at arbitrary wavelength, therefore, eliminating the requirements on the optical nonlinearity and the photonic resonance at the signal wavelength. Furthermore, a technique to improve the transverse-modulation-induced relative delay of light in nonlinear media through the combination of an optical nonlinearity and a resonant Fabry-Perot cavity was introduced and theoretically demonstrated in ruby as an example. The introduction of a resonant Fabry-Perot cavity can improve the relative delay by orders of magnitude. The techniques of active chromatic manipulation and resonant improvement of the group delay of light may have potential applications in optical information processing and optical communication network.