Research And Design Of Tunable Optic Fiber Delay Line And Broadband Erbium-doped Fiber Source

In recent years, the technology of DWDM and EDF amplifier has been developing fast. The optical fiber communication system makes a direction for wider bandwidth and longer distance. Not only wide bandwidth signal's processing but also broadband light source are demanded. Optical fiber delay line can process signal in frequency or time domain and has many advantages comparing with the traditional electronic delay line. Also the erbium-doped fiber source has many favorable characteristics such as broad spectrum, high and stable output power, low cost and small volume, convenient to couple with single mode fiber. Certainly they will get extensive application in the future, and starting the research work right now seems to be very meaningful.Based on the principle of optical fiber delay line, several modules of delay line are introduced compendiously. In chapter 2, we will introduce several optical delay line and analyze their advantages and disadvantages. Several 3-bit tunable optical fiber delay units are designed and analyzed.In order to improve the delay precision, the technology is researched from two sides in the following chapter: on one hand, the structure of delay unit is redesigned; on the other hand, a new technology using tunable laser as light source of delay system is proposed. By calculating and deducting the states of optical switches and delay error, a new delay unit consisted of six 1x2 optical switches is designed. The theoretical delay in ideal circumstances and the theoretical dynamic delay by altering the wavelength of the LD are simulated respectively. The simulation results indicate that, the mean error of time delay can be amended dynamically, and the delay precision of the optical fiber delay line is remarkably improved.A new structure of broadband light source combine with optic syntonic module is proposed to take the place of tunable laser at the last chapter, and a broadband erbium-doped fiber source is designed and manufactured on the basal conditions of our laboratory. With the wavelength select function of optic syntonic module, we can achieve wavelength's continuous tunable of the broadband erbium-doped fiber source. So the new structure could take the function of the tunable laser completely.Because the tunable optical fiber delay line designed in the thesis has a very low delay error, so it would have very important theoretic and practical meaning in some fields, where there are needs of high delay precisions.