International Journal of

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In this paper, by including Raman scattering in the coupled-mode equations, the scalar modulation instability in photonic crystal fibers is investigated. The evolution of the pump, Stokes and anti-Stokes waves along the fiber as well as the conversion efficiency for two cases, with and without Raman effect, are studied. The effect of anti-Stokes seed and the pump depletion on the evolution of Stokes wave is also considered. Moreover, the parametric gain when it is affected by Raman gain is dealt with. The results show that it is important to take into account Raman scattering, especially for wide-bandwidth parametric amplifiers which results in an asymmetric spectrum and more amplification of the Stokes wave.

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A polymethylmethacrylate (PMMA) microstructured polymer optical fiber (mPOF) is fabricated and characterized. Using the cut-back technique the fiber loss is measured which is higher than the step-index silica fibers. Through a novel experimental scheme, the backward Stokes spectrum of the fabricated mPOF is recorded over a range exceeding 3000 cm^‑1 during the cut-back method and compared with that of step-index silica fiber. Especially, the gain coefficient of the Raman peak at 2950 cm^‑1 is directly measured, that is without comparing with other known material. The results show a very good agreement with those obtained through other experimental schemes.