Study On Super-Fluorescent Source And Spectral Division

Since erbium-doped fiber super-fluorescent source has put forward in1989, Super-fluorescent light with high output power, wide spectral width, low coherency, easy fiber coupling, good stability and low noise figure is considered as the promising broadband light source and is developing rapidly. How to use the existing communication system to widen the communication capability in order to meet increasingly demands has became the hotspot of the optical communication research realm, when all kinds of data services require more and more transmission bandwidth. Study indicated that using C-band and L-band signal transmission at the same time to achieve expansion in the existing WDM system directly, is a very effective method to fully exploiting the bandwidth of fiber optical transmission potential. Therefore, super-fluorescent light is the key device in WDM system and its development in future is of important significance for increaseing the capacity of optical fiber communications system.In this context, this paper did a research of software simulation and experimental studies on super-fluorescent light source, respectively C-band and L-band ASE source for the formation of a more rational structure model, and got better results. On this basis, their Spectra division experiments were also conducted to study, with the hope that this research could provide theoretical and experimental information for expanse WDM communication systems.First, the paper introduced the development of light, the advantages of super- fluorescent light, the status quo at home and abroad and relevant background knowledge, and also did a relatively detailed presentation about the different super- fluorescent light pumped structure - with the pump, reverse-pumped and pumped two-way.Secondly, from the theory and the principle of super-fluorescence, level structure and rate equations of erbium ions, the characteristic parameters and super- fluorescent light of the different structures (one way forward, after the one-way, two-way forward, Two-way after and the structure of optical fiber amplifier), this thesis did a more detailed elaboration. And introduced some important passive optical devices used in the experiment (such as fiber Bragg grating, fiber-optic ring mirror, optical round, etc). All of this, made a brief presentation for the paper to lay a solid theoretical foundation.At the same time, this paper used OptiAmplifier software simulation to observe the effects of certain parameters to output spectrum of Super-fluorescent light, such as pump power, mirror in different parameters, length of erbium-doped fiber.Thirdly, the experimental study about super-fluorescent light was done. C-band and L-band super-fluorescent light experimental model was built. Having used two erbium-doped fibers with different concentration and a broadband fiber- optic ring mirror which could reflect part of super-fluorescent into erbium-doped optical fiber and make optical amplification again, the Super-fluorescent Source output power was effectively improved. The results of the C-band super-fluorescent light experimental model are as follows: threshold power is 5mW, output power increase with the pump power linearly, when the pump power is 120mW, a high output optical power of 46mW can be gained with power stability of±0.02dB, and the efficiency of output optical power compared to pump power is about 40 percent, while maintaining low intensity noise.In the design of The L-band super-fluorescent light, through software simulation we can see that the high concentration of erbium fiber can make up for the length of erbium fiber, therefore, this paper used a higher concentration of erbium-doped fiber as a gain medium. Compared with previous literature, greatly reduce the length of erbium-doped fiber to produce L-band fluorescence light. The experimental results of model can be as follows: threshold pump power is 18mW, output power increase with the pump power linearly, when the pump power is 120mW, a high output optical power of 25mW can be gained with power stability of±0.02dB, and the efficiency of output optical power compared to pump power is about 24.5 percent. Finally, we focused on the design of two different Super-fluorescent light source spectra division structure. The series-wound spectra segmenting system is putting a number of Fiber Bragg Grating tandem which separate a single wavelength of light from super fluorescent light, exporting through corresponding optical circulator. Through the analysis of experimental results, as each Fiber Bragg Grating class brought a loss, the optical power will be reduced step by step after transmitting grating tandem. Therefore, optical power passed series-wound spectra segmenting system is not balanced. Parallel Spectra segmentation system using a coupler is divided into four-way and put a Fiber Bragg Grating in every way. Through the analysis of experimental results, it found that compared with the series-wound system, although optical power of super-fluorescent light passed a parallel system is reduced, it can gain more uniform optical power output.Parallel segmentation system was used in this paper to divide up a single- wavelength light, and then a simple modulation transmission experiment was built. This paper set up an experimental platform of modulation. After transmitting 10km distance in single-mode fiber, the receiving en spectral was got and analyzed. The paper found that after the modulation and transmission, the basic shape of the main module has not change, only a slight reduction in peak power. Therefore, the conclusion that the parallel fiber grating system is an ideal multi-wavelength spectrum segmentation model can be gained. The multi-wavelength light source through the model with symmetrical power output value can be used in optical communications wavelength division multiplexing system which can transmit voice, images and video as Simple inexpensive communications source.In sum, this thesis seriously analyzed the principle, design process, debugging process, output characteristic of super-fluorescent source and spectral division, on the hope that these researches could provide worthy theories and the technique support for further research and development of super-fluorescent source.