Vertically Pluggable and Compact 10-Gb/s$\,\times\,$12-Channel Optical Modules With Anisotropic Conductive Film for Over 100-Gb/s Optical Interconnect Systems

Abstract

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> We have developed a vertically pluggable and compact 12-channel optical module for intercabinet and intracabinet optical interconnections. Error-free and over 10 Gb/s operation of the optical module with an electrical and optical connector have been demonstrated. The module is designed to be 10 mm in width, 10 mm in length, and 6 mm in thickness so that it can be placed around the central processing units. This compact optical module can be mounted on the inner board area. Further, this module is vertically pluggable in the <formula formulatype="inline"><tex Notation="TeX">${z}$</tex></formula>-direction, i.e., in a direction that is perpendicular to the board. Because of the vertical pluggability, the optical modules can be repaired much more easily. The optical connector used in the low-height module has 12 fine-drawn graded-index multimode fibers (MMFs). These fibers have a high relative refractive index difference (<formula formulatype="inline"><tex Notation="TeX">$\Delta$</tex></formula>) and are bent with a 2 mm radius of curvature. The electrical connector consists of an anisotropic conductive film that is sandwiched between an alumina substrate and a printed circuit board with a clamp spring. We have used the alumina substrate to mount the optical device and the driver integrated circuit, because of its high thermal conductivity. In order to reduce cost, we have not used either a microlens or a metal-coated mirror in the optical module. Furthermore, passive alignment between the MMFs and the optical device has been achieved using guide pins assembled in the alumina substrate. </para>