25 September 1998 Polyimide-based guided-wave multigigabit per second optical clock signal distribution system for Cray T-90 supercomputer
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Proceedings Volume 3417, Photopolymer Device Physics, Chemistry, and Applications IV; (1998) https://doi.org/10.1117/12.323482
Event: Lasers and Materials in Industry and Opto-Contact Workshop, 1998, Quebec, Canada
Abstract
We report the formation of polyimide-based H-tree waveguides for a multi-GBit/sec optical clock signal distribution in a Si CMOS process compatible environment. Such a clock distribution system is to replace the existing electronic counterpart associated with high-speed supercomputers such as Cray T-90 machine. A waveguide propagation loss of 0.21 dB/cm at 850 nm was experimentally confirmed for the 1-to-48 waveguide fanout device. The planarization requirement of the optical interconnection layer among many electrical interconnection layers makes the employment of tilted grating a choice of desire. Theoretical calculation predicts the 1-to-1 free-space to waveguide coupling with an efficiency as high as 95 percent. Currently, a coupling efficiency of 35 percent was experimentally confirmed due to the limited index difference between guiding and cladding layers. Further experiments aimed at structuring a larger guiding/cladding layer index differences are under investigation. To effectively couple an optical signal into the waveguide through the tilted grating coupler, the accuracy of the wavelength employed is pivotal. This makes the usage of the vertical cavity surface-emitting lasers (VCSELs) and VCSEL arrays the best choice when compared with edge-emitting lasers. Modulation bandwidth as high as 6 GHz was demonstrated at 850 nm. Such a wavelength is compatible with Si-based photodetectors.
© (1998) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Hong-Fa Luan, Linghui Wu, Bipin Bihari, Jianhua Gan, Ray T. Chen, Suning Tang, Randy W. Wickman, Bruce R. Pecor, Yung-Sheng Liu, "Polyimide-based guided-wave multigigabit per second optical clock signal distribution system for Cray T-90 supercomputer", Proc. SPIE 3417, Photopolymer Device Physics, Chemistry, and Applications IV, (25 September 1998); doi: 10.1117/12.323482; https://doi.org/10.1117/12.323482
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