Optical Fiber Array Connector Designed for Assembly Automation
Authors: Terry P Bowen, Aleksandar K Angelov, Steve Dellinges, Thomas Huegerich, Wayne Montoya, Frances T Peralta, Nick Pugliano, Sandeep Razdan, Jibin Sun, Jian Wang, John Wasserbauer, and Haipeng Zhang Company: TE Connectivity Date Published: 2/11/2014
Pan Pacific Symposium
Abstract: A new sub-assembly compatible with standard MT / MPO connectors was designed and fabricated. The sub-assembly precisely aligns optical fiber arrays on the MT standard footprint, so that mating to legacy MT / MPO connectors is possible. The prospect of staging multi-level fiber arrays into a single MT (mechanical transfer) connector with a design intended for automation of the fiber termination is the thrust of this paper. A typical MT fiber array installation procedure consists of coating removal of the fibers, threading them into tight fitting fiber bores, an adhesion/fixation step, followed by removal of excess fiber length, and finally optical polishing of the fiber/ferrule end-face. This complicated process is time consuming, and the longitudinal threading of fibers into the MT fiber bores is difficult to automate. The fiber gripper sub-assembly presented in this paper will facilitate precision placement of the optical fibers using a lateral motion for the fiber presentation and placement. This is a key step designed to enable automation of the process. In this paper, the design concept, and two fabrication procedures of the proposed fiber-gripper are demonstrated. Wafer scale technologies are implemented in the fabrication. In a first option, a polymer material such as SU-8, commonly adapted in the MEMS field, is utilized. This negative-tone, photo-epoxy is deposited as a thin film on the wafer substrate. A trench array is created using standard photolithography steps such as spin coating, followed by a soft bake, UV-illumination, post-exposure bake and development. A hard bake / final cure has been added to insure that the SU-8 functionality is permanently set. The resulting photo-imaged resist ridge structures feature thermally cross-linked vertical sidewalls that form periodically spaced trenches where the optical fibers are inserted. SU-8 is known for its mechanical strength, chemical resistance, and thermal stability. The linear array of ridge structures is on a pitch of 250 um. Fundamental studies on thickness distribution and variability were conducted. In a second option, wet etched silicon v-groove arrays were formed to provide the accurate fiber positioning structures. Statistical data on dimensions of the structures by profilometry were collected. We were able to consistently produce good quality alignment structures with well-defined features.