Lineshapes in Nonlinear Spectroscopy

Abstract

Much precision metrology and the determination of fundamental constants depends on spectroscopy of atoms and molecules. Generally the limiting factor in precision spectroscopy is the lineshape, both the width and the various shifts of the center. To reduce the broadening and shifts a number of nonlinear spectroscopic techniques have been developed. These are techniques where the signal is proportional to the product of two or more oscillating fields. I would like to give a general discussion of the lineshapes obtained in the two most widely used techniques which will be mentioned at various times during the conference in the context of specific experiments or uses. The lineshapes I will consider are those encountered in the separated oscillatory fields approach introduced by Ramsey, and in saturated absorption spectroscopy.