Wavelength-Switchable And Q-switched Fiber Lasers Experimental Research

Fiber lasers possess many good qualities, such as wide range of wavelength,excellent beam quality,highly converted efficiency and long working time, which not only make them play an increasing role in the communication field, but also become one of the most widely researched laser sources in the field of laser technology recently, especially in the field of high power double-clad doped fiber laser, which has become a researching focus nowadays. With the pursuit of high power and the extreme power limit of single fiber laser, the coherent combination of fiber lasers has become a new researching focus. In this paper, we focus on the research of fiber laser and coherent combination of fiber lasers, and meantime obtain a series of achievements. Main works are abstracted as follows:1. A narrow linewidth dual-wavelength switchable Erbium-doped ring fiber laser was obtained, which was based on the principle of interaction of fiber loop mirror(FLM),fiber Bragg grating(FBG) and polarization controller(PC), and the stable work in single or dual-wavelength could be achieved by adjusting the PC at room temperature, the wavelength separation is 0.07 nm and linewidth is less than 0.04 nm.2. With a phase mask, the fiber Bragg gratings can be fabricated directly in a multimode double-clad Yb³⁺-doped fiber as the frequency selective mirror, utilizing the multimode FBG, we designed a multi-wavelength double-clad fiber laser. Through adjusting the polarization controller, single-, dual-, triple- and four wavelengths stably output respectively can be achieved at room temperature. The wavelength was near 1060 nm and linewidth was less than 0.02 nm; under a 25 W pump power of 976 nm laser, the maximum output power of the laser was above 6 W in multi-wavelength.3. A high power passive Q-switched fiber laser was designed by using a GaAs wafer as the saturable absorber and the D-shape inner clad Yb³⁺-doped fiber. The maximum average output power is 7.2 W at 1080 nm wavelength, with the shortest pulse duration of 580 ns and the highest peak power of 160 W when the laser was pumped with a 25 W diode laser operating at 976 nm. The highest repetition rate is 77 KHz with the energy of 93.5μJ. The graph of pulse repetition rate versus pump power was researched, and the aspects of affecting pulse duration also was analyzed.4. The basic theory and main methods of coherent combination of fiber lasers was studied in this paper, and through a primary experiment of self-organization coherent combination with two fiber lasers, only a power combination of them was achieved due to less coherent character of the two fiber laser,. In this experiment, one fiber laser output is 0.968 W, and the other fiber laser output is 0.910 W, while the combination power is 1.87 W.