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arXiv · 1307.4268

Optically induced mode conversion in graded-index fibers using ultra-short laser pulses

Tim Hellwig·Till Walbaum·Carsten Fallnich
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Abstract

We propose the use of graded-index few-mode fibers for mode-conversion by long-period gratings (LPG) transiently written by ultrashort laser pulses using the optical Kerr effect. The mode inter- action is studied by numerically solving the multi-mode coupled nonlinear Schroedinger equations. We present highly efficient conversion of the LP 01 - into the LP 11 -mode preserving the pulse shape in contrast to previous results in step-index fibers. Furthermore, mode conversion using different wavelengths for inducing and probing the LPG is shown. Due to the flat phase-matching curve of the examined modes in the graded-index fiber, mode-conversion can be observed for probe center wavelengths of 1100nm up to 1800nm with a write beam centered around 1030nm. Therefore, a complete separation of the probe from the write beam should be possible as well as the application of optically induced guided mode conversion for all optical modulation across a broad wavelength range.

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Tim Hellwig, Till Walbaum, Carsten Fallnich. 2013-09-19. Optically induced mode conversion in graded-index fibers using ultra-short laser pulses. https://doi.org/10.1007/s00340-013-5645-5

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