Diffractive Optics in Free-Space OptoElectronic Computing Systems

Optical interconnections have been shown to have advantages over electrical interconnections in terms of speed, energy, and density for global links1. In addition, the flexibility of optical interconnections permits efficient electronic layouts that can improve the performance of electrical connections in an opto-electronic computing system. Optical interconnections systems are currently a very active area of research2,3,4,5. These systems typically combine electronic circuits, opto-electronic transmitters and receivers, and optical elements. Electronic circuits are usually designed, optimized, and fabricated using standard VLSI technology. Many technologies are available for opto-electronic transmitters and receivers; in our case, we will use either Si/PLZT6,7 or Si/MQW8 technologies. Similarly, there is a wide choice of technologies available for the optical elements in the system. In this paper we first present some results on diffractive elements for Free-Space Interconnection systems fabricated using e-beam direct write technology. Then we discuss the design and optimization of the diffractive elements used in a particular free-space optical interconnection scheme: the optical transpose interconnection system (OTIS); where we have used CodeV®9 optical system design software package to design and optimize several different systems based on both refractive and diffractive micro-optic technologies. In addition, we have explored the possibility of using a volume holographic element to replace the need for a polarizing beam splitter in the system.