Anomalous dispersion: a new measurement approach

A technique for instantaneously viewing discrete points along an anomalous dispersion curve has been successfully demonstrated. A Fabry-Perot interferometer was used to spatially resolve the axial modes of an HF probe laser. A Michelson interferometer, one leg of which contained an HF absorption cell, imposed lines of constant phase. Recorded fringe shifts could then be used to determine the refractive-index change between axial mode frequencies, thus enabling construction of the dispersion profile.