3-D Integrated Optical Microcircuits in Lithium Niobate Written by Spatial Solitons

Integrated optical microcircuits are structures based on optical waveguides to confine light and consequently to make it realize operations and functionalities. Consequently, the basic element of any integrated circuit is the waveguide. It is constituted of 3 main spatial regions: the propagating core and the surrounding media, the upper and lower ones. In order to confine light, the propagating core must show a higher refractive index than the surrounding media in order to ensure a total reflection regime of the optical rays trapped inside the core area. Consequently, the propagating light proceeds inside the waveguide with a particular configuration called mode, which means the overall interference between all the trapped waves. According to the refractive index contrast between core and surrounding media and according to the transverse dimension of the waveguide, one or many modes can propagate: however, if there is just one mode or many, the characteristic of every mode is to keep its transverse profile constant along the whole propagation. Thus, the mode is a steady-state solution of the light propagation equation inside the confining structure called eigenstate.