Minimum lens complexity design approach for a free-space maro-optical multi-chip; global interconnection module

摘要

The FAST-Net (Free-space Accelerator for Switching Terabit networks) concept uses an array of wide field-of-view imaging lenses to realize a high-density shuffle interconnect across an array of smart-pixel integrated circuits. This paper presents a design approach for these lenses that achieves the minimum complexity required to meet the emands of the FAST-Net concept's off-axis multi-chip environment. Generalized eikonals for arbitrary surface were examined to determine the performance bounds for the FAST-Net optical system.s Then an alaysis provided an estimate of 6 for the number of spherical surfaces needed to achieve good optical resolution and distortion performance across an array of 10-micron dameter VCSEL sources that are imaged onto an array of 50-micron wide detectors. A ray trace simulation confirmed this number. Subsequent analysis evaluated the achievable efficiency of replacing spherical surfaces with aspherical ones. By exploiting the mismatch between the low numerical aperture VCSELs and relatively higher numberical aperture interconnection optics, it was found that 3 aspherical surfaces could replace 6 spherical surface in the FST-Net system for the specified performance criteria. A lens design that utilizes 3 asperhical surfaces and achieves necessary registration and resolution of th FAST-Net system was determined. The results provide a general framework for the design of wide field-of-view free space interconnection systems that incorporate high-density VCSEL arrays.