Voltage-tuned multiwavelength Raman ring laser with high tunability based on a single fiber Bragg grating.

A practical scheme for a tunable multiwavelength Raman fiber ring laser based on a single fiber Bragg grating with a voltage-controllable coil heater is investigated. The number of phase-shifted regions within a single fiber grating determines the number of reflection peaks and the number of lasing wavelengths in the multiwavelength Raman fiber ring laser. A stable multiwavelength Raman fiber ring laser with low output peak-power fluctuation of less than 0.5 dB at room temperature is achieved. A multiwavelength Raman fiber ring laser with a high extinction ratio of more than 50 dB is realized. High flatness is obtained for three lasing peaks, and the lasing peak-power difference is measured to be less than 0.2 dB. A voltage-controllable coil heater with heating elements is used to effectively control three lasing wavelengths in the multiwavelength output, and the tunability of each lasing wavelength is measured to be 0.11 nm/V.