Study Of 1550 Nm And 2μm Fiber Lasers Based On Nonlinear Effects

Fiber laser is one of the most important technologies in modern photonics research and industry, thanks to its wide application in almost every fields of society. Due to the boosting demands of fiber-optic communication, fiber sensing systems, and microwave generation, fiber lasers operated near 1550 nm have been well developed. On the other hand, with the "eye-safe" property,2μm waveband has attracted much attention and become one of the hot topics, due to its potential in spectroscopy, next generation fiber-optic communication, wind measurement, and medical surgery. Aiming at these applications, the thesis presents our studies of 1550 nm multiwavelength fiber optical parametric oscillator (FOPO), thulium-doped fiber laser, 2μm Brillouin laser based on chalcogenide fiber, and 2 μm hybrid Brillouin-thulium multiwavelength fiber laser.Briefly, the history and recent development of laser technology as well fiber technology are presented. Then we focus on the 1550 nm multiwavelength fiber lasers and claim the advantages of multiwavelength FOPOs in practical uses.The fruitful applications of 2 μm waveband, together with the recent development in 2 μm laser sources, are also introduced, resulting in the necessity of 2 μm fiber laser technology.Brought with the potential in WDM fiber-optic networks, the principles of fiber optical parametric amplifier (FOPA) and FOPO are introduced. Then, FOPA’s optimal pump setup and several optical comb-like filters are investigated. After analyzing the recent research work on multiwavelength FOPOs, three novel multiwavelength FOPOs based on Sangac ring, Lyot-Sangac ring and Mach-Zehnder interferometer were proposed and demonstrated with a fixed, switchable and tunable wavelength spacing, respectively. In conclusion, the series of multiwavelength FOPOs would be proper candidates for specific applications.Starting with the introduction of 2 μ waveband and its role in spectroscopy, medical surgery, and nonlinear photonics research, a few possible schemes realizing 2 lasers are presented, including rear-earth element ion doping method and diode laser technology. The advantages of thulium doping scheme are then investigated, and based on which, we propose a wavelength tunable 2 μm thulium-doped fiber laser. With a Fabry-Perot filter as the wavelength decision element, a 70 nm tuning range of our laser was obtained and a wavelength sweeping operation was demonstrated.Then, practical applications like spectroscopy and gas sensing at 2 μm are studied. Based on the advantages of 2 μm waveband and narrow linewidth operation, a scheme of 2 μm low threshold Brillouin laser is proposed. The principle and key parameters of stimulated Brillouin scattering (SBS) process are well investigated. Recent research work in this field is then introduced, to which some improvements are made to meet the challenge of realizing a Brillouin laser operated at 2 μm. We proposed and demonstrated the first Brillouin laser at 2 μm based on suspended-core chalcogenide fiber. A record-low threshold of 52 mw was obtained, which was 2 orders lower than previous report based on silica single mode fiber (SMF). Moreover, the size of the gain medium was also 10 times smaller.Finally, we look into the next generation fiber-optic communication technology and sensing system, in which 2 μm multiwavelength fiber lasers act as the key elements. Then we analyze the previous reports of 2 μm multiwavelength fiber lasers and propose the idea of employing SBS effect. We proposed and demonstrated the first hybrid Brillouin-thulium multiwavelength fiber laser, whose wavelength spacing could be flexibly switched between single and double Brillouin frequency-shift. A good temporal output power stability and wavelength tunability were also offered, which effectively extends the lasers’ potential in practical applications.This thesis concentrates on experimental studies as well as theoretical analysis. Pursuing the application at both 1550 nm and 2 μm, several novel fiber laser schemes were proposed and experimentally demonstrated. We believe, these work would be of favor and importance to the community of 1550 nm and 2 μm fiber lasers.