Supercontinuum decoherence due to XPM-assisted Raman amplification in normal dispersion fibers for polarization or wavelength offset pulses

Feehan, James and Price, Jonathan (2019) Supercontinuum decoherence due to XPM-assisted Raman amplification in normal dispersion fibers for polarization or wavelength offset pulses. Journal of the Optical Society of America B, 37 (3), 635-644. (doi:10.1364/JOSAB.379563). (In Press)

Record type: Article

Abstract

We report the importance of cross-phase modulation (XPM) on the coherence of a low-energy probe pulse co-propagating with a high-energy pump pulse which generates incoherent supercontinuum in all-normal dispersion (ANDi) fiber due to Raman amplification of quantum noise. By investigating numerous fiber and pulse parameters we show consistently that for weak probe pulses the XPM from the pump is the dominant influence on the degradation of the probe coherence. We show that the faster decoherence at the pump leading edge means that the probe coherence is reduced more significantly when the probe has a higher group velocity, i.e., when an orthogonally-polarized probe is aligned to the fast (lower refractive index) axis of the fiber or when a co-polarized probe has a longer central wavelength. Simulations show that this effect occurs for both polarization maintaining (PM) and non-PM ANDi fibers and can result in a probe decoherence rate which is higher than that of the pump. These previously unreported results extend our earlier scalar simulations showing incoherent supercontinuum within a single pulse.

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