FIELD-CORRELATION EFFECTS IN 2-PHOTON ABSORPTION FROM RANDOMLY AMPLITUDE-MODULATED LASER FIELDS

We report measurements of the absorption spectrum for two-photon absor ption from a variety of randomly amplitude-modulated laser fields. The fields are generated by modulating the output of a stabilized tunable ring dye laser external to the laser cavity. As such, the field stati stical properties are controllable and well characterized. The fields which we have used in this investigation include the real Gaussian fie ld, the complex Gaussian field, and the real Gaussian field with a coh erent component. For the last field, an interesting correlation effect is seen when the coherent component is in phase or 90 degrees out of phase with the stochastic component. We have also investigated the eff ect of partial correlation of the two counterpropagating fields used i n the measurements. In all cases we find excellent agreement between t he measured absorption spectra and those calculated from the known fou rth-order field-correlation functions.