Research On Single-Mode Brillouin/Erbium Fiber Lasers And Their Applications

High-accuracy distributed Brillouin optical fiber sensors promise great significances in architectural health detection, fire and mountain collapse alarming, etc. For high-precision signal demodulation in Brillouin sensors, a beam of Brillouin-frequency-shift light is demanded as the referenced light in heterodyne-detection Brillouin optical time domain reflectmetry (BOTDR) or detecting signal in Brillouin optical time domain analysis (BOTDA). Based on Brillouin fiber lasers, Brillouin/erbium fiber lasers (BEFLs) have potential applications in Brillouin fiber sensors, due to their Brillouin-frequency-shift output. Besides, their narrow linewidth (~kHz) and high output power (~mW) promise great applications in coherent optical communication, interferometry sensors, microwave photonics and etc. So researches on single-mode BEFLs are of important realistic significances.On the Bases of application potentials of BEFLs in distributed Brillouin optical fiber sensors and many other fields, this thesis studies single-mode Brillouin/erbium fiber lasers including operation principles, output characteristics verses cavity structures and parameters, and applications to optical carrier suppression. By combining the Brillouin pump pre-amplification technique, a single-mode ultra-short ring-cavity (~10m) Brillouin/erbium fiber laser adopting single-mode fiber is actualized. The main work and innovation are as follows:(1) The basic principles of BEFLs are analyzed in detail, including stimulated Brillouin scattering and erbium-doped fiber amplifying. The laser structure and operating process as well as laser rate equations are detailed introduced.(2) A BEFL of 4.9km single-mode fiber is constructed and investigated on its laser and residual pump output characteristics, including spectrum, output power, laser modes and their relations with Brillouin pump, erbium-doped fiber pump, single-mode-fiber length as well as intracavity tunable bandpass filter.(3) By combining tunable bandpass filter and Brillouin pump pre-amplification technique, with only 5m single-mode fiber, a single-mode ultra-short ring-cavity BEFL is realized. It presents excellent properties, including low threshold, high output power (~10mW) and wide tunable range over C-band. The ultra-short-cavity BEFL is the key to further researches on single-frequency BEFL.(4) A BEFL of 25km single-mode fiber is constructed and investigated on its optical carrier-suppression characteristics. Its potential applications in distributed Brillouin fiber sensing are analyzed in detail.