Nonlinear photoemission for viewing guided or evanescent waves

Photoelectrons generated by multiphoton absorption can be used to form images of evanescent waves or modes in optical waveguide surface structures. With high resolution electron optics, it is possible to observe detail in the photoelectron image that is much smaller than the light wavelength. This technique therefore may be useful in revealing submicron waveguide defects and in visualizing evanescent wave phenomena. In this paper the chatacteristics of this method are discussed, and preliminary experiments in which nonlinear photoemission images of GaAs and LiNbO3were obtained are described.