Research On Optic Interconnection Networks On Chip Based On Microring Resonators

Interconnection networks must transport an always increasing information density and connect a rising number of processing units, but their inherent limitations are the difficulties. More attentions are paid to the bandwidth, power consumption and the anti-interference performance based on electrical interconnection, which are difficult to meet the need of development. Moore’s Law is beening broken sooner or later. At the same time, optical interconnection has already had the trend of making up for and even replacing the electrical interconnection, with the development of optical interconnection. It has the huge advantages in bandwidth, power consumption and the anti-interference performance. Optical interconnection has already been the key to break through the bottleneck, especially new photonic devices can be directly integrated in CMOS technology.In this paper, optical interconnection networks on chip based on the microring resonators are studied, which includes the design of the basic components and the optimization of networks topology on chip. The main researches are as follows:(1) We systematically summarize the whole process of the design of optical interconnection networks on chip based on the microring resonators. It concludes the selection of materials, the design of basic cascaded-double-rings and intersected-double-rings and the selection of networks, which are described in detail.(2) The performance parameters of cascaded-double-rings and intersected-double-rings are derived by the transfer matrix, such as transmission characteristic(T), field enhancement factor(FE), fineness(F) and free spectrum rang(FSR), et al. Then we know how the coupling coefficient and the radius(R) have influence upon these parameters and finally complete the design of basic components. The cascaded-double-rings is designed at a resonance wavelength of 1550 nm, and its radius is 6.987 μm, width of waveguide is 200 nm, the gaps are 90 nm(between direct waveguide and ring) and 80 nm(between ring and ring). While the intersected-double-rings at an resonance wavelength of 1550 nm is also completed, with the radius of 6 μm, width 270 nm, gap 80 nm.(3) We focus on the point to point N×N interconnection networks based on cascaded-double-rings, and describe a 4×4 network as an example. Thermal tuning is employed to make the microrings to be in resonance or not. The design has many advantages, for example, it is easy to integrate and make use of less rings. The insertion loss is about 2.2 d B, extinction ratio is more than 140 d B, and FSR is about 20 nm. Only two rings are needed to be deal with when routing a signal, which helps to reduce energy consumption.(4) We also make attempts to complete the 8×8 Benes network based on intersected-double-rings. With the completed intersected-double-rings, we design the 8×8 Benes network, and optimize the connection waveguide between different units. By the simulation, the performance improvements in the areas and energy consumption are proved in comparison with crossbar network and Clos network.