Study On Fiber Laser Based On Special Fiber Filter

Single-wavelength, dual-wavelength and multi-wavelength fiber lasers with high performance have broad application prospects in the field of high-speed large-capacity optical communication systems, Radio Over Fiber systems, coherent optical communication systems and optical sensing networks. And the good performance, high stability, low cost, easy to manufacture and easy to integrate fiber filter, is a key devices for single-wavelength, dual-wavelength and multi-wavelength fiber laser with high-performance. In this paper, with the help of the National Natural Science Foundation of China and Beijing Jiao tong University Outstanding doctoral student of science and technology innovation fund projects, to study the novel fiber filters for breakthrough, several novel fiber filters based on special fiber are conducted in-depth theoretical and experimental research, and the structure and performance of single-wavelength, dual-wavelength, and multi-wavelength fiber laser based on research several novel filters were designed and optimized, respectively. The main innovative results obtained are as follows:1. The dual channel MZ interferometer filter based on asymmetric twin-core fiber (DPMZI-ATCF) was proposed and designed to improve the performance of dual-wavelength lasers. The model of the DPMZI-ATCF was established by a transfer matrix method. By combining theories and experiment, the reflection spectrum characteristics of the filter was studied. a comb spectrum with the same wavelength intervals and different reflectivity was obtain. a single or double switch switchable wavelength erbium-doped fiber laser (EDFL) was designed and fabricated using the filter experimentally. The side mode suppression ratio greater than62.47dB of the dual-wavelength fiber laser was achieved, and wavelength interval was tuned from0.155nm to4.041nm. The laser as Photo-millimeter wave technology microwave photonics offers students an ideal light source.2. The dual-pass MZ interferometer filter based on dual polarization maintaining fiber (DPMZI-PMF) was proposed. A single or double switchable wavelength EDFL was designed and fabricated using the filter experimentally. By adjusting the polarization controllers (PCs), the single-and double-wavelength laser output was switched, the single-wavelength laser with3dB line-width0.0146nm, and side mode suppression ratio(SMSR) up to69.55dB was obtained, while the SMSR of the dual-wavelength laser was greater than64.0dB, wavelength tunable interval range has been further expanded, the minimum wavelength spacing was reduced to0.084nm, the maximum wavelength interval was added to4.28nm.3. The single-and dual-wavelength switching and wavelength EDFL was proposed and fabricated in experiment. A composite filter was made of a transmission type loop filter (TRT)/reflective type loop filter (RRT) and the DPMZI-PMF filter. By adjusting the PCs and using the filter, single and double switches and tunable wavelength laser output were obtained separately. Single and dual wavelength were adjusted in the wide range from1561.03nm to1569.16nm and1563.57nm to1568.88nm respectively, while the dual-wavelength spacing was tuned from0.01nm to4.34nm, and the dual-wavelength laser possessed a peak power balance. Compared with other methods, to achieve the same peak power output of the dual-wavelength laser. The laser had advantages of output wavelength stability, easy to control, and low cost.4. A stable and tunable single wavelength EDFL with high SMSR based on a compounded fiber filter, which was composed of high-precision optical fiber (HF-F) filter and DPMZI-PMF filter, was proposed and fabricated. A single-wavelength laser with linearly polarization and SMSR as high as72.11dB was achieved, and The output laser wavelength was tunable in the range of1560.37nm to1568.56nm. The laser had a good prospect in the field of optical communication systems, long distance optical sensor networks and optical measurements.5. A stable switchable multi-wavelength linear cavity fiber lasers was presented based on nonlinear rotational effects (NPR). By using non-linear loop mirror symmetrical structures, the NPR effects, which effectively suppressed homogeneous broadening effect in erbium-doped fiber. Using asymmetric twin-core fiber (ATCF) as a wavelength selection filter, up to52lasing wavelengths with signal noise ratio (SNR)of more than32dB was achieved. The mulitiwavelength fiber laser could be used as a multi-channel DWDM system ideal source.6. Using ATCF filter, a switched multi-wavelength fiber laser was proposed based on a stable complex physical mechanisms. By introducing NPR effects and polarization dependent loss effects-complex physical mechanisms, the homogeneous broadening effect in erbium-doped fiber had been effectively controlled, thereby mode competition and mode hopping had also been suppressed.45lasing wavelengths with a SNR up to41.5dB was obtained. The mulitiwavelength fiber laser provided an efficient source for high-capacity dense wavelength division multiplexing systems and optical sensing networks.