Generation of Raman sidebands aided by a CW Stokes signal

• Broad cascaded Raman sidebands in PCFs are experimentally demonstrated.
• Each peak has the 3 dB line-width smaller than 0.5 nm.
• The generated cascaded Raman sidebands contain four Stokes and six anti-Stokes peaks, and spread over a broad spectrum range of 893–1491 nm.

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 ~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.