Polymeric slot waveguide phase shifter with liquid crystal cladding: numerical modeling and fabrication flow

In this paper we present the scheme of an optical phase shifter based on a SU-8 slot waveguide with a liquid crystal upper cladding. It has been obtained after an evaluation of the fabrication process flow and the numerical optimization/modeling of waveguides. We studied numerically the achievable phase shift through a combination of 2D Finite Element Method and index ellipsoid diagram. We also show that a slot configuration of the waveguides allows to sustain both quasi-TE and quasi-TM modes, while ensuring more interaction between the guided signals and the cladding. The choice of the materials and fabrication processes was operated by selecting established methods and procedures, and gauging the compatibilities. Given the high phase shifting efficiency and the accessibility of the fabrication processes, this component can be a key element for the development of compact and inexpensive devices which are suitable for many applications in computation, communication and sensing.