Fast and Accurate Free Space Propagation Based on Automatic Operator Selection

Several methods are well established for free space propagation including spectrum of plane waves (SPW), Fresnel propagation, far field integral and geometrical optics. From these methods only SPW is a method without a physical error. However, in order to keep numerical errors small, SPW often requires large computer resources. On the other hand, the requirements of other operators are often smaller but their physical error might be too large depending on the particular propagation task. In the talk we present a new propagation technique that selects automatically the most appropriate propagation operator in terms of physical and numerical error and computational effort. The selection is based on estimates that take into account the field to be propagated and the propagation distance. We show that the resulting automatic operator covers a wide range of propagation tasks. Additionally the approach gives an insight into numerical and physical approximation properties of the basic propagation operators for different types of fields and propagation distances. The software LightTrans VirtualLab(TM) provides the described methods and is used for the numerical examples that are shown.