Flexibly tunable multiwavelength Raman fiber laser based on symmetrical bending method

A practically tunable multiwavelength Raman fiber laser based on few-mode fiber Bragg gratings without additional multichannel filters is investigated. We achieved high quality of the Raman laser output with a high extinction ratio of more than 45 dB. The number of lasing wavelengths can be adjusted by the properties of few-mode Bragg gratings with multiple resonant wavelengths. The lasing wavelength of Raman fiber laser can be readily controlled by the tension and compression strain, which correspond to the directional bending curvature change. The dynamic range of lasing wavelength change was more than 15 nm.