Multimode Optical Fibers With Harmonically- Tempered Refractive Index Profile Functions

Abstract

We introduce a new approach for design of refractive index profile functions in multimode optical fibers. The main feature of the proposed scheme is the low-parameter independent control of mode properties, achieved by tempering refractive index profile functions with additive oscillating components. As a proof-of-concept, we demonstrate acquisition of two modified graded-index multimode fibers with substantially reduced differential mode group delay (DMGD) for fifteen LP modes. For a fixed wavelength, the first fiber reveals max <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$|$</tex-math></inline-formula> DMGD <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$|$</tex-math></inline-formula> of 810 fs/km that is two orders of magnitude smaller than that of the current best result. The second fiber provides max <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$|$</tex-math></inline-formula> DMGD <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$|$</tex-math></inline-formula> not exceeding 50 ps/km in S, C and L bands. Finally, we show that the obtained optimized fiber properties can be unaffected by realistic manufacture imperfections for a wide range of wavelengths, thus highlighting high potential of the proposed design scheme.