Broadband tuning of polarization modulation instability in microstructured optical fibers

The wideband tuning of strong bands generated through polarization modulation instability (PMI) in microstructured optical fibers (MOFs) is reported. Tunability is achieved by exploiting the dependence of the phase-matching condition on the fiber's chromatic dispersion and birefringence, which is particularly sensitive when the fiber is pumped near the zero-dispersion wavelength. MOFs designed to accomplish PMI phase-matching when they are infiltrated with ethanol and pumped at 1064 nm were designed and fabricated. Taking advantage of the large thermo-optic coefficient of ethanol, both chromatic dispersion and birefringence were varied through temperature. Wavelength shifts from 937 nm to 863 nm (anti-Stokes) and from 1231 nm to 1387 nm (Stokes) are demonstrated. Such a tuning range corresponds to a frequency shift between the pump and a PMI sideband ranging from 1274cm^-1 to 2189cm^-1.