Planar lightwave integrated circuits with embedded actives for board and substrate level optical signal distribution

© 2004 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.DOI: 10.1109/TADVP.2004.831894As the data rate of integrated circuits dramatically increases, interconnection speed at the backplane and board levels are beginning to limit system performance, which drives investigations into alternative interconnection technologies. Critical factors to consider when evaluating alternative interconnection approaches include interconnect speed, power consumption, area, and compatibility with current backplane and board integration technologies. Optical interconnections can achieve very high speed with a significant reduction in interconnect footprint compared to transmission lines, robust signal quality in high-density interconnection systems because of immunity to electromagnetic interference, and potentially simple to design (compared to transmission lines) lines with materials which can be postprocessed onto printed wiring boards or integrated into the board structure. This paper explores design options for planar optical interconnections integrated onto boards, discusses fabrication options for both beam turning and embedded interconnections to optoelectronic devices, describes integration processes for creating embedded planar optical interconnections, and discusses measurement results for a number of integration schemes that have been demonstrated by the authors. In the area of optical interconnections with beams coupled to and from the board, the topics covered include integrated metal-coated polymer mirrors and volume holographic gratings for optical beam turning perpendicular to the board. Optical interconnections that utilize active thin film (approximately 1-5 µm thick) optoelectronic components embedded in the board are also discussed, using both Si and high temperature FR-4 substrates. Both direct and evanescent coupling of optical signals into and out of the waveguide are discussed using embedded optical lasers and photodetectors