Switchable dual wavelength picosecond fiber laser source operating around 780 nm for advanced Raman spectroscopy

A picosecond laser emitting alternatively two wavelengths separated by 1 nm around 780 nm is demonstrated. This source is designed for advanced Raman spectroscopic measurements for which two spectra at two different pump wavelengths are acquired. The difference between the two measurements permits to discriminate the Raman contribution from the noise (SERDS). For such purpose, we developed a mode-lock fiber laser delivering a broad optical spectrum around 1560 nm which provides, through filtering with Fiber Bragg Gratings, the two required wavelengths operation. Second Harmonic Generation at 780 nm is then performed with a fibered coupled bulk PPLN.