High speed board-to-band interconnection system using optical slots for backplane applications

Abstract

A practical optical board-to-board interconnection system was proposed with transmitter/receiver processing boards and an optical backplane made of polymer-waveguide-embedded, optical PCB. As connection components between the transmitter/receiver processing boards and backplane board, optical slots were suggested to enable easy and repeatable insertion and extraction of the boards with micrometer precision. The basic concept of the optical board-to-board interconnection system is as follows; 1) Metal optical bench is integrated with optoelectronic devices, driver and receiver circuits, polymer waveguide and access line (printed circuit board) PCB module. 2) Multimode polymer waveguide inside an optical backplane, which is embedded into PCB, 3) Optical slot and plug for high-density (channel pitch : 500 $\microm$) board-to-board interconnection. The optical and electrical total losses occurred in an optical board-to-board interconnection system were analyzed via a system power budget design. And optical and electrical signal integrity (SI) problems were discussed and solved by ADS momentum simulation in electrical regions and a ray tracing method in optical regions. Through the analysis, differential traces resistant to electrical crosstalks were designed for the transmission lines in transmitter and receiver boards and optical coupling between VCSEL chips and multimode waveguide were completed through the analysis of 1.0 dB misalignment tolerance in the optical loss. In this dissertation, misalignment tolerance satisfying 1.0 dB optical coupling loss are analyzed as $\plusmn$ 8 $\microm$ and $\plusmn$ 7 $\microm$, respectively. The simulation results showed enough alignment margins for the total power budget. The polymer waveguide technology can be used for transmission of data between transmitter/receiver processing boards and backplane boards. The main components are low-loss tapered polymer waveguides and a novel optical plug and slot for board-to-boar...