Compensation of Multimode Fiber Dispersion Using Adaptive Optics via Convex Optimization

• Published in: Journal of lightwave technology Vol. 26; no. 10; pp. 1295 - 1303
• Main Authors: Panicker, R.A., Kahn, J.M., Boyd, S.P.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 15.05.2008; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Adaptive algorithms; Adaptive optics; Algorithms; Applied sciences; Circuit properties; Compensation; Constraint optimization; Convex analysis; Dispersions; Electric, optical and optoelectronic circuits; Electronics; Exact sciences and technology; Impulse response; Integrated optics. Optical fibers and wave guides; Intersymbol interference; Nonlinear filters; Optical and optoelectronic circuits; Optical fiber dispersion; Optical fiber polarization; Optical fibers; Optical modulation; Optical propagation; Optimization; Phased arrays; Reflectivity; Spatial light modulators; spatial light modulators (SLMs); Studies; Second order; spatial light modulators (SLMs); Multimode fibers; Adaptive algorithm; Eye diagram; Computational complexity; Convex programming; Implementation; Optimization; Optical fiber dispersion; Simulation; Intersymbol interference; Pulse response; Spatial light modulators; Adaptive optics; Reflectance
• ISSN: 0733-8724; 1558-2213
• DOI: 10.1109/JLT.2008.917324

In this paper, we propose a provably optimal technique for minimizing intersymbol interference (ISI) in multimode fiber (MMF) systems using adaptive optics via convex optimization. We use a spatial light modulator (SLM) to shape the spatial profile of light launched into an MMF. We derive an expression for the system impulse response in terms of the SLM reflectance and the field patterns of the MMF principal modes (PMs). Finding optimal SLM settings to minimize ISI, subject to physical constraints, is posed as an optimization problem. We observe that our problem can be cast as a second-order cone program, which is a convex optimization problem. Its global solution can, therefore, be found with minimal computational complexity, and can be implemented using fast, low-complexity adaptive algorithms. We include simulation results, which show that this technique opens up an eye pattern originally closed due to ISI. We also see that, contrary to what one might expect, the optimal SLM settings do not completely suppress higher order PMs.