High-Bandwidth and Large Coupling Tolerance Graded-Index Multimode Polymer Waveguides for On-Board High-Speed Optical Interconnects

Abstract

Abstract-Optical interconnects have attracted significant research interest for use in short-reach board-level optical communication links in supercomputers and data centres. Multimode polymer waveguides in particular constitute an attractive technology for on-board optical interconnects as they provide high bandwidth, offer relaxed alignment tolerances, and can be cost-effectively integrated onto standard printed circuit boards (PCBs). However, the continuing improvements in bandwidth performance of optical sources make it important to investigate approaches to develop high bandwidth polymer waveguides. In this paper, we present dispersion studies on a graded-index (GI) waveguide in siloxane materials designed to deliver high bandwidth over a range of launch conditions. Bandwidth-length products of >70 GHz×m and ~65 GHz×m are observed using a 50/125 μm multimode fibre (MMF) launch for input offsets of ±10 μm without and with the use of a mode mixer respectively; and enhanced values of >100 GHz×m are found under a 10× microscope objective launch for input offsets of ~18 × 20 μm 2 . The large range of offsets is within the -1 dB alignment tolerances. A theoretical model is developed using the measured refractive index profile of the waveguide, and general agreement is found with experimental bandwidth measurements. The reported results clearly demonstrate the potential of this technology for use in high-speed board-level optical links, and indicate that data transmission of 100 Gb/s over a multimode polymer waveguide is feasible with appropriate refractive index engineering.Index Terms-optical interconnections, polymer waveguides, multimode waveguides, waveguide dispersion

Monolithic optical link in silicon-on-insulator CMOS technology

“…Here, a maximum on-off keying speed of only 70 kHz was reached. SOI technology also offers monolithic waveguiding, which has shown potential applications in high-level hybrid integration for cost-effective high-performance computing [22,23]. Significant advances have been made to integrate optical data communication in the past, but most of them utilized hybrid solutions for inter-chip data transfer [1,23].…”

Bandwidth Enhancement in Multimode Polymer Waveguides Using Waveguide Layout for Optical Printed Circuit Boards

“…Due to the ever increasing demand for higher interconnection bandwidth, conventional copper-based electrical interconnects impose a performance bottleneck owing to their inherent disadvantages. Optical technologies provide a promising solution to this issue owing to their advantages over their electrical counterparts: higher bandwidth, lower crosstalk and improved power efficiency [2]. Multimode polymer waveguides are considered to be an excellent candidate for use in board-level optical interconnects enabling the formation of electro-optic (EO) printed circuit boards (PCBs).…”

Low loss, flexible single-mode polymer photonics

“…Despite these advantages, single-mode polymer waveguides generally exhibit much higher propagation losses compared to their multi-mode counterparts. While propagation losses as low as 0.03 dB/cm have been demonstrated in multi-mode waveguides [25][26][27][28][29][30][31][32][33], the minimal loss figures in single-mode waveguides remain at 0.14 dB/cm (at 808 nm wavelength [33]) mainly due to increased modal overlap with roughness and defects at the core/cladding interfaces.…”