Design, assembly, and testing of an objective lens for a free-s pace photon i c switching system

Free-space optical switching and computing systems utilize macroscopic optical elements such as holograms, gratings, lenses, and mirrors as their basic hardware building blocks. In these systems, information is carried by arrays of beams of light that are collimated, manipulated, and focused onto spatial light modulators (SLMs) in a stage-by-stage fashion. The photonics switching work at AT&T Bell Laboratories has involved the fabrication of several prototype systems18 with increasing complexity and functionality. The motivation in developing free-space optical switching systems is the opportunity offered by optics to interconnect a large number of communication channels at a high bit rate. There are various engineering issues involved in a practical optical system for switching and computing. In this paper, the design, assembly, and testing of a lens for a free-space multistage optical switching system capable of manipulating an array of 4096 beams are discussed.