Efficient Coupling Mechanisms for Planar Integrated Optical Systems

Planar optics is well suited for various applications within the fields of optical interconnects, telecommunication, security etc. Due to the use of diffractive optical elements, the overall efficiency of systems demonstrated so far is rather small, i.e. in the range of a few percent. A specific problem is the efficient coupling of the optical beam into the substrate. Diffractive optics is here limited by the trade-off between minimum feature size, deflection angle and efficiency of the deflection grating. The coupling efficiency can be increased significantly e.g. by using prisms or prism arrays. In this case the locations of the object and image planes might be shifted. Furthermore the optical path lengths for different object points vary significantly. We investigate the impact of these aspects on the optical design of the overall system. To this end we compare the optical performance of planar optical imaging systems based on the standard 4f-imaging configuration. Simulations of the imaging quality of the systems for different coupling mechanisms as well as optimum designs are presented.