Low-cost and facile assembly strategy for fiber ribbons and integrated optical waveguides with MT-ferrule-compatible optical connector

Abstract

Polymer waveguides are expected to be applied to optical circuit boards for high-speed optical interconnection where conventional connectors are normally required. We presented a novel optical connector assembled optical printed circuit board (OPCB) approach that possessed potential to meet packaging requirements, including reflow-soldering-compatibility, high reliability and low insertion loss. An in-plane coupling technique that actively mechanically transferable (MT) connectorized on rigid FR4 substrate with alignment features was demonstrated. Here, 230 mm-long waveguides with step index and approximate 50×50 μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> geometric profiles were fabricated. The propagation loss of the waveguide was approximately 0.15 dB/cm at the wavelength of 850 nm, which was sufficiently small to satisfy the basic requirement for optical circuit boards. A dicing saw process was used to fabricate the alignment slots that was used for carrying MT-ferrule-compatible optical connector. The polymer waveguides were butt-coupled with the standard MT-type connectors to realize optical coupling between optical waveguides and fibers. Besides, the manufacturing, optical functionality, and environmental reliability of the related multimode optical waveguide devices were also investigated. The average total insertion loss of optical waveguide channels was approximately 6.5 dB, and optical return loss was measured to be -35 dB or even lower. Moreover, the high-speed optical signal transmission tests have been demonstrated that error-free and clear eye openings were achieved at a data rate of 10 Gb/s. The fabricated rigid optical circuit board with MT connectors could withstand 1000 hours 85 °C/85%RH relative humidity test, 1000 hours thermal shock test as well as 5 cycles of lead-free reflow soldering test. Hence, the presented low-cost, mass-productive and facile assembly strategy of connector to seamlessly interface optical fiber ribbons with polymer optical waveguides has attractive practical application in board-level high-speed optical interconnection.