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Abstract:
We present the results of an experiment proving in principle that negative (anomalous) dispersive transparent media can be realized. The Ca-transition 4s(2) S-1(0) --> 4s4p(1)P(1) at lambda = 423 nm was chosen to investigate the absorption and index of refraction spectra of a two-level system strongly driven at resonance. For the simultaneous high precision measurement of loss and phase shift imposed on a probe field during the interaction with a chopped Ca-atomic beam we used a novel spectrometer which is based on a phase modulated Mach-Zehnder interferometer. So far, a dispersion of partial derivative(omega)n(o), = -(3.1 +/- 1.0) X 10(-10)/MHz accompanied by residual absorption of alpha(0) = (0.125 +/- 0.040)%/cm has been achieved. These values are compared to the requirements which have to be achieved for a certain application of negative dispersion without absorption, that is for a broadband high build-up cavity (white-light cavity)
