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Proceedings Paper

Polyimide-based guided-wave multigigabit per second optical clock signal distribution system for Cray T-90 supercomputer
Author(s): Hong-Fa Luan; Linghui Wu; Bipin Bihari; Jianhua Gan; Ray T. Chen; Suning Tang; Randy W. Wickman; Bruce R. Pecor; Yung-Sheng Liu
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Paper 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.

Paper Details

Date Published: 25 September 1998
PDF: 5 pages
Proc. SPIE 3417, Photopolymer Device Physics, Chemistry, and Applications IV, (25 September 1998); doi: 10.1117/12.323482
Show Author Affiliations
Hong-Fa Luan, Univ. of Texas/Austin (United States)
Linghui Wu, Univ. of Texas/Austin (United States)
Bipin Bihari, Univ. of Texas/Austin (United States)
Jianhua Gan, Univ. of Texas/Austin (United States)
Ray T. Chen, Univ. of Texas/Austin (United States)
Suning Tang, Radiant Research, Inc. (United States)
Randy W. Wickman, Cray Research, Inc. (United States)
Bruce R. Pecor, Cray Research, Inc. (United States)
Yung-Sheng Liu, General Electric Research and Development Ctr. (Taiwan)

Published in SPIE Proceedings Vol. 3417:
Photopolymer Device Physics, Chemistry, and Applications IV
Roger A. Lessard, Editor(s)

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