Sn–Ag–Cu Solder Reflow-Capable 28-Gb/s × 4-Channel High-Density Parallel-Optical Modules

This paper describes a unique solution to the next-generation high bit-rate and high channel-density parallel-optical links whereby the size of parallel-optical modules would have to be considerably reduced. Since the main problem concerning the size of optical-to-electrical conversion part is associated with the mounting of the parallel-optical module to the printed-circuit-board (PCB), this paper puts forward a remarkably compact parallel optical-module design that can be soldered directly onto the PCB. That is made possible by the high temperature tolerance of 250 °C required for Sn-Ag-Cu solder-reflow process. The miniature parallel-optical module measures only 10.5 mm in length, 6.5 mm in width, and 1.5 mm in height. The resulting parallel-optical modules are capable of four-channel error-free parallel pseudo-random binary sequence 2³¹-1 transmission at 28 Gb/s without using clock and data recovery as well as feed-forward error correction (FEC); hence, these parallel-optical modules are applicable in next-generation high-density 100 Gb/s Ethernet applications that use FEC.