An experimental and theoretical study of the offset launch technique for the enhancement of the bandwidth of multimode fiber links

• Published in: Journal of lightwave technology 1998-03, Vol.16 (3), p.324-331
• Main Authors: Raddatz, L., White, I.H., Cunningham, D.G., Nowell, M.C.
• Format: Article
• Language: English
• Subjects: Applied sciences; Bandwidth; Circuit properties; Connectors; Electric, optical and optoelectronic circuits; Electronics; Ethernet networks; Exact sciences and technology; Integrated optics. Optical fibers and wave guides; Optical and optoelectronic circuits; Optical fiber communication; Optical fiber dispersion; Optical fiber LAN; Optical fiber theory; Optical fibers; Refractive index; Stability
• ISSN: 0733-8724; 1558-2213
• DOI: 10.1109/50.661357

This paper reports an experimental and theoretical study of bandwidth enhancement in multimode fiber links achieved by using offset launch techniques. It is found, both from theory and experiment, that an up to four-fold bandwidth enhancement can be obtained compared to standard overfilled launch techniques despite exciting over 50% of the fiber modes, thus allowing good stability. The enhancement technique is found to be achieved for a range of fibers with different core diameters and core refractive index profiles. The level of bandwidth enhancement depends upon the inherent bandwidth of the fiber, being particularly effective in improving the performance of low bandwidth "worst case" fibers. The launch is found to be stable with respect to environmental variations, showing bandwidth enhancement for injection positions or connector offsets of up to 5 /spl mu/m from optimum. In addition, unlike many restricted launch techniques, it is found to be tolerant to angular fiber misalignment for angles up to 6/spl deg/ from normal.