Abstract: An electro-optical device having a non-volatile programmable refractive index. The device includes: a waveguiding structure with waveguiding material, the waveguiding structure defining an optical beam path, where the waveguiding structure includes a transition metal oxide with oxygen vacancies that migrate when exposed to an electric field; and a plurality of electrodes for applying an electric field to a region including the transition metal oxide with oxygen vacancies; where the transition metal oxide and the electrodes are arranged such that under the applied electric field the oxygen vacancies migrate in a direction that has a component which is radial relative to a center of the beam path. Further, there is provided a method for making the electro-optical device, including: fabricating the waveguiding structure; positioning a plurality of electrodes for application of an electric field; and arranging the transition metal oxide and the electrodes.