Diffractive near-field array generators

ABSTRACT In this paper, we compare and summarize the features of two types of two-dimensional array illuminators - the binary zoneplate array and the Talbot array illuminator - both producing a spot array in the near field without the addition of any opticalcomponent. Numerical evaluations of the illumination efficiency are based on the scalar theory. We present and discussfurthermore the experimental results obtained by such array illuminators when fabricated under the same conditions, i.e., by optical lithography and two masks (four-level binary optics). INTRODUCTION Array illuminators are passive optical devices that provide an efficient distribution of optical power of a single optical beam to an array of active areas or optical input ports. Efficient optical multiplexing is considered important for highly-parallel opticaldata processing systems, spatial light modulators, and optical interconnects'. The motivation behind this work is to sort out features and drawbacks of both the Talbot array illuminator (TAIL) and thebinary zone plate array (BZPA) 2 to look at their similarities and differences, and finally to obtain a better picture of which