Optical interconnects

Handbook of Optical Interconnects, edited by Shigeru Kawai... 

For data transfer applications the modulation speed of an emitter is a decisive parameter. Here the long lifetime of the excited state in PS becomes problematic. The fall time of the EL is usually in the ps regime, while somewhat shorter values are reported for the rise time. Only for devices based on OPS has a significantly shorter fall time (0.03 ps) been reported [WalO]. For small signal modulations of the EL from PS, frequencies in the order of 1 MHz are reported Ts4, Co5]. Such modulation frequencies are sufficient for display applications. For data transfer via optical interconnects, however, they are much too low. 

J. J. Fijol, E. E. Fike, P. B. Keating, D. GUhody, J. Leblanc, S. A. Jacobson, W. J. Kessler, M. B. Frish, Fabrication of silicon-on-insulator adiabatic tapers for low loss optical interconnection of photonic devices, Proc. SPIE 4991, 157-170 (2003). 

These characteristics show that perfluorinated polyimides are promising materials for waveguides in integrated optics and optical interconnect technology. The thermal, mechanical, and optical properties of perfluorinated polyimides can be controlled by copolymerization in the same manner as partially fluorinated polyimides. ... 

Stability for use in optical interconnects. In the near future, optoelectronic integrated circuits and optoelectronic multichip modules will be produced. Materials with high thermal stability will thus become very important in providing compatibility with conventional 1C fabrication processes and in ensuring device reliability. Polyimides have excellent thermal stability so they are often used as electronic materials. Furuya et al. introduced polyimide as an optical interconnect material for the first time. Reuter et al. have applied polyimides to optical interconnects and have evaluated the fluorinated polyimides prepared from 6FDA and three diamines, ODA (3), 2,2-bis(3-aminophenyl) hexafluoropropane (3,3 -6F) (4), and 4,4 -6F (2), as optical waveguide materials. 

The simple analysis presented above confirms that new formulations are required to produce stable, reliable products for field use. Practical system requirements, as defined by Mil Spec conformity and the use of standard fabrication and assembly processes, definitely require that a electro-optic polymer system with better thermal properties than thermoplastic acrylates be developed. That this is true for optical interconnection boards and modules is not surprising because of their complexity. It is perhaps remarkable that it remains true for even simple devices, such as a packaged, pigtailed traveling-wave modulator. The ultimate success of electro-optic polymers will be their use in cost-effective products that are used by systems designers. 

As the materials mature, it is expected that practical fabrication problems will be solved, and that eventually various grades of E-0 polymers will be available, like photoresist is today, for a variety of different applications and needs. For this reason, polymers represent a unique, potentially powerful addition to the library of materials comprising optoelectronic components, and polymer devices provide new and novel approaches to optical interconnection, electronic packaging, and integrated optics. 

Electrical and Optical in Same Board Multilevel Optical Interconnects... 

The ability to integrate an electro-optic material with other optical devices, e.g. light sources and detectors, and with electronic drive circuits is important. Integrability implies that the electro-optic materials and the processing of these materials are compatible with the other components, and that electrical and optical interconnects can be fabricated. Polymer glasses are widely used in the fabrication of electronic devices and device interconnects. Polymers are also used as photoresists and as dielectric interlayers for electrical interconnects. As a result, a body of knowledge already exists concerning planarization methods of polymers on substrates, the definition of microscopic features, and the fabrication of microstructures in planar polymer structures. 

Nanoparticles are rapidly gaining popularity in biomedical, optical and electronic areas. Zapping tumors with multi-walled carbon nanotubes, solar cells to light-attenuators and chip-to-chip optical interconnects in futuristic circuitry are some of the potential applications. Thus finding novel ways for the synthesis of these new age materials is of paramount interest where radiation chemistry is modesdy playing a role and the chapter on metal clusters and nanomaterials deals with these aspects. 

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