Gain Properties Of Fiber Optical Parametric Amplification Based On Lightwave Regulation

Fiber-optic parametric amplificatiaon (FOPA) is a new optical amplification technique based on four wave mixing (FWM), which has the obvious advantages of providing high gain uniform over a wide wavelength range, complete transparence to the signal bit rate and modulation formate, low noise figure, phase sensitivity, compatible with all fiber devices and so on. What is more, the FOPA has potentional advantages in all optical signal-processing, and it is considered as one of the most suitable optical amplifiable techniques for the future ultra-long-distance dense wavelength division multiplexing (DWDM) all-optial networks. Therefore, the FOPA has attracted increasing attencion recently as a new type of fiber optical amplifier. However, it is a very important issue to find some new ways of increasing and optimizing the gain spectrum of the FOPA. Considering the profound background, in this work, the lightwave regulation method is presented and concentrated on the influcnes to the gain properties of the FOPA, with the purpose of achieving the optimized gain method and investigating them deeply both from the theory and experiment. The main contents of the dissertation are as following.The basic theory of the FOPA is investigated comprehensively at first, as well as the main structure. And based on the principle of the FWM, the theory model is analyzed in the case of one-pump FOPA and two-pump FOPA, respectively, at the same time, both the signal gain without pump depletion and the gain with pump depletion are discussed. The phase matching condition and the analytical solution of signal gain without pump depletion are given for both the one-pump and two-pump cases. What is more, the amplification systems of both the one-pump FOPA and the two-pump FOPA are achieved experimently.The scheme of the FOPA based on lightwave regulation is presented and analized. Afer the derivation of the theory modle of the signal gain without pump depletion, the solution of the signal gain is given, meanwhile, the gain characteristics of the FOPA system is optimized obviously with the simulation and discussion.By using the standard single mode fiber (SSMF) connecting between two high nonlinear fibers (HNLFs), the cascaded systems of FOPA are designed. The SSMF is applied to compencate the phase mismatch parameter of the involed waves. The numerically simulation shows that the signal gain is increased and the gain bandwidth is broaded with the SSMF inserting between HNLFs, and the comb gain spectrum is observed. Furthermore, the amplification experimental flatform is set up and tested, and the result shows that the gain is improved, which is consistently with the simulation mentioned before.Next, the phase shifted fiber Bragg gratting (PS-FBG) is unilized to shift the phase of the pump wave in order to research the influence to the gain of FOPA. With the way of pump phase shifter (PPS), FOPA can gain flattened gain spectrum. In the case of the fixed signal wavelength, compareing with the system without inserting PPS, it can be seen that the phase matching is compensated and the signal gain is increased obviously with using PPS. On the other hand, the flat gain bandwidth is also abtainted by analyzing the gain spectrum.For the first time, the solution to enhance the efficiency of fiber optical parametric amplification is proposed by regulating the idler wave, and both the phase and the power properties of the idler wave are regulated. Firstly, the one-pump FOPA is designed by using an optical bandpass filter (OBPF) between two HNLFs to filter the idler wave, and it shows that both the signal gain and the pump-to-signal conversion efficiency are enhanced, with the gain flatter at the same time. Secondly, a PS-FBG is also adopted between two HNLFs to shift the phase and reflect the power of the idler wave during the amplification processing. The result shows that the phase mismatch is compensated, the relative phase difference of the involved waves is changed and the signal gain is improved clearly. Then influence of the reflectivity and phase shifter of the PS-FBG to the gain property are also discussed. At last, the experimental one-pump FOPA system via fiber Bragg grafting (FBG) reflecting the idler wave between two same HNLFs is constrocted and analyzed. The experimental results show that the sigal gain is increased, and the conversion efficiency of the pump power transferred to the signal power is enhanced synchronously.