Channel waveguides of Rb+exchanged single‐crystal KTiOPO4were studied by micro‐Raman spectroscopy. Rb+exchange causes a disruption of the long‐range translational (crystal) symmetry of the lattice and a tilting of the TiO6octahedra. The ability to nondestructively map the chemical and physical structure related to the optical properties of channel waveguides is demonstrated. ©1995 American Institute of Physics.