Research On Wavelength-tunable Fiber Lasers At 2?m

Due to being located in the atmospheric transmission window and covering the spectral absorption peaks of H2O?CO2 and other molecules, eye-safe lasers at 2 ?m have a variety of attractive applications in the fields of atmospheric remote sensing and biomedical. All-fiber wavelength-tunable fiber lasers at 2 ?m have attracted a lot of attentions in recent years due to their compact configuration, wide wavelength-tunable ranges and high stability. This paper carried out comprehensive researches on wavelength-tunable fiber lasers at 2 ?m. By utilizing a wideband tunable filter, we achieve all-fiber widely tunable Tm/Ho-codoped fiber laser and Tm-doped fiber laser, respectively. By utilizing a master oscillator power amplifier system, we achieve a wavelength-tunable laser at 2 ?m with more than 100 W output power. The primary contents are shown as follows :1. The research background of wavelength-tunable fiber lasers at 2 ?m is introduced. According to the material of the gain fiber used in laser, the developments of wavelength-tunable Tm-doped, Ho-doped and Tm/Ho-codoped fiber lasers at 2 ?m are reviewed. The development trend of wavelength-tunable lasers at 2 ?m is analysed.2. We design and achieve an experimental scheme of an all-fiber widely tunable Tm/Ho-codoped fiber laser. By utilizing a diffraction grating based tunable filter as the wavelength selection device, we achieve an all-fiber Tm/Ho-codoped fiber laser with wavelength-tunable range of 1727-2030 nm. The 303 nm wavelength-tunable range of the laser is the widest among the reported all-fiber rare-earth-doped fiber lasers. The influence of pump power and Tm/Ho-codoped fiber length on the wavelength-tunable range of the laser is researched. The experimental results show that with the increase of pump power, the short-wavelength end of the Tm/Ho-codoped fiber laser wavelength-tunable range is extended towards the short-wavelength direction. With the increase of Tm/Ho-codoped fiber length, the short-wavelength end of the Tm/Ho-codoped fiber laser wavelength-tunable range is extended towards the long-wavelength direction.3. We design and achieve an experimental scheme of an all-fiber wavelength-tunable Tm-doped fiber laser with more than 100 W output power. Firstly, we achieve a widely tunable Tm-doped fiber laser. By utilizing a master oscillator power amplifier system to scale up the output power of the wavelength-tunable Tm-doped fiber laser and optimizing the length of Tm-doped fiber used in the main amplifier, an all-fiber wavelength-tunable Tm-doped fiber laser with more than 100 W output power is first reported. The output powers of the laser in the wavelength-tunable range of 1940-2050 nm are all achieved more than 100 W. The maximum output power of the laser is achieved 115 W at 1950 nm with the slope efficiency of 51.67%.