Controlling stimulated coherent spectroscopy and microscopy by a position-dependent phase.

We study the role of geometry dependent phase shifts in stimulated coherent spectroscopy, a special class of heterodyne optical spectroscopy techniques. We generalize the theoretical description of stimulated spectroscopy to include spatial phase effects, and consider the measured material response for several representative excitation and detection configurations. Using stimulated Raman scattering microscopy as an example, we show that different components of the material response are measured depending the position of the object in focus. We discuss the implications of the position dependent phase in stimulated coherent microscopy and point out a detection configuration in which its effects are minimized.