Generation of Raman sidebands aided by a CW Stokes signal

We experimentally demonstrate that adding a continuous wave Stokes signal to a picosecond pulse will significantly expand the spectra or help to generate broad cascaded Raman sidebands in an index-guided photonic crystal fiber when pumping in the normal dispersion regime. The generated twelve Raman peaks, spaced by similar to 13.2 THz, contain four Stokes and six anti-Stokes peaks, and spread over a broad spectrum range of 893-1491 nm. Each peak has a 3-dB line width smaller than 0.5 nm. The cascaded Raman sidebands make it promising to get the wavelength-tunable Raman sources. (C) 2013 Published by Elsevier Ltd.