A Novel Soft-lithography Based, Vertically Coupling Structure For Multilayered Optical Interconnection

Today, we live in the midst of an information explosion. The rapid development of computing and communications technologies has opened an entirely new world. Although the ability of information processing of electronic system increasing steadily, the means of interconnecting these devices has remained relatively stationary, relying on conductive electrical lines. The performance of advanced electronic systems is increasingly limited by constraints imposed by interconnects and this limitation will inevitably become more serious as the operating frequency increases and the feature size reduces. Electrical interconnects suffer from problems such as frequency dependent loss, EMI and crosstalk at high data rates that limit the available bandwidth, and become the main bottleneck on the performance of systems.Optical interconnects have gained interest worldwide over the last years in view of their ability to offer a possible solution to the bandwidth problems associated with electrical interconnects. Optical interconnects, which have proven their potential in chip-to-chip communication systems on main boards, transport data faster, consume less power and transfer data more accurately at high data rates.A novel vertical coupling structure is designed for multilayered optical interconnect in this paper, one of most promising approaches for high speed communications in next-generation computer. In addition, we fabricate this newly designed interconnection using soft lithography technique, which can dramatically reduce cost, simplify production procedures and increase efficiency.First, the paper discusses the disadvantages of electrical interconnection and advantages of optical interconnection, and introduces the presently basic conditions of optical interconnection.Then, detailed design for the vertical coupling structure is followed. The layer-to-layer coupling features a simple structure with an insertion loss as low as 0.05dB. For four cross-sections of 30×30μm~2,50×50μm~2 , 100×100μm~2 , and 200×200μm~2 calculations for cross-over of up to 6 layers were performed using ray-tracing simulation tool ZEMAX, it was found that a low-loss coupling can be achieved as the ratio of cross height to traveling distance is about 0.128.At last, Prototypes were fabricated by using soft-lithography and measurement agrees with the calculated result in general.