title: High-power and highly efficient operation of wavelength-tunable Raman fiber lasers based on volume Bragg gratings.
abstract: Highly efficient and high-power operation of Raman fiber lasers in fixed-wavelength and wavelength-tunable cavity configurations based on a graded-index multimode fiber is reported. Fixed-wavelength and wavelength tunable operating regimes are achieved using volume Bragg gratings (VBGs) with center wavelengths of 1658 nm and 1750 nm, respectively. The fixed-wavelength laser yielded a maximum output power of 10.5 W at 1658.3 nm with a FWHM linewidth of ~0.1 nm for the launched pump power of 23.4 W, corresponding to a slope efficiency of 82.7% with respect to the launched pump power. The measured beam quality in the form of M² factor is ~1.35, corresponding to the fundamental mode of the fiber. For the wavelength-tunable Raman fiber laser, a wavelength tuning range of 37 nm from 1638.5 to 1675.1 nm is obtained with a maximum output power of 3.6 W at 1658.5 nm for the launched pump power of 13.0 W.
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.forename: Deyuan
authors.initials: D
authors.lastname: Shen
authors.forename: Haitao
authors.initials: H
authors.lastname: Huang
authors.forename: Chujun
authors.initials: C
authors.lastname: Zhao
authors.forename: Xiaoqi
authors.initials: X
authors.lastname: Zhang
authors.forename: Dianyuan
authors.initials: D
authors.lastname: Fan