Theoretical And Experimental Investigation On Super-broadband Fiber Amplifier

The erbium-doped fiber amplifier (EDFA) is emerging as a landmark in the history of the development of fiber-optic communications, and it accelerates the development of WDM/DWDM (Wavelength Division Multiplexing/Dense WDM) communications systems. At the same time, there appears some further demand to the EDFA as the development of WDM/DWDM, such as the broad bandwidth, automatic gain control and automatic power control.According to the project of super-broadband fiber amplifier and flattened EDFA and thulium-doped fiber amplifier, this dissertation focuses on the study of TDFA, L-EDFA (Long wavelength-band EDFA), and the flatness and gain control of EDFA. The main contents are listed as follows.1. Firstly, the rate equations for population changes and the propagation equations for the pump and signal beams had been introduced. And the Giles Model was deduced in detail. At the last, we studied the change of the gain and noise figure (NF) of the EDFA as the pump power, the length of the erbium-doped fiber (EDF), the pump scheme or the wavelength of the pump beam via stimulation by using the software of Lucent OASIX. The change of the saturated output power as the pump scheme, or the wavelength of the pump beam was also studied.2. We studied the gain flattening of an EDFA by using a high-birefringence fiber loop mirror (FLM). With a two-section high-birefringence FLM, we are able to flatten the amplified spontaneous emission (ASE) profile of an EDFA within a range ±ldB over a 35nm bandwidth in the region from 1527 to 1562nm, under different operating conditions of the EDFA.3. We studied the gain controlling of an EDFA by using a pair of tunable fiber Bragg grating. Various stabilized gain levels that had different range of input signal power and various gains could be achieved by tuning the center wavelength of a grating. The gain excursion can be controlled in the range of ±0.2dB.4. The variations of the gain as the pump power or the length of the EDF were studied by simulation using the software of the company of the Optiwave. And the influence of the ratio of the forward and backward pump power in bi-direction pump scheme to the gain was studied.5. The L-band signal amplifier had been achieved using two different schemes based on using backward ASE as pump resource. And the gain enhancement was studied by using the method of injecting an accessory laser. It is easy for the accessory laser transferring its energy to the closer signal and we found the long wavelength laser is better than short wavelength laser forgain enhancement.6. A novel forward-pumped reflection L-band EDFA (L-EDFA) with a FLM as the reflector was presented. For a given input pump power, compared to the traditional forward-pumped L-EDFA, in the region from 1570 to 1605nm, the gain of the reflection L-EDFA is improved by 5.33dB and the saturation output power is increased by 3dB. The characteristics of the gain and NF and saturation output power of three types of reflection L-EDFA with different pump schemes were studied.7. A novel bi-direction pumped reflection L-EDFA was presented. With the same pump power and the length of the EDF, compared to the traditional forward-pumped reflection L-EDFA, in the region from 1565 to 1615nm, the gain of the bi-direction pumped reflection L-EDFA are enhanced by 1.5-9.4dB, and the NF are descended by 1.3-9.4dB. The gain variety dropped and the 3dB bandwidth is over 30nm, the gain excursion is only +0.45dB in the region from 1570 to 1600nm.8. A flat high efficiency super-broadband source was presented. We achieved a C+L-band super-fluorescent source, in the region from 1524.0 to 1600.4nm, the power of the ASE are over -12.0dBm and the ASE profile excursion is only d:1.4dB in the region from 1539.2 to 1600.4nm. The power of the ASE is 22. lmW and the power conversion efficiency is 18.8%.9. The amplification characteristics of thulium-doped fiber amplifier (TDFA) had been studied using the basic theory for fiber amplifier. The connection between the Tm-doped fluoride fiber and silicon fiber was accomplished, and we studied the TDFA and the reason that the expecting results hadn't achieved had been analyzed. The assumption of the Er-Tm-co-doped silicon fiber had been presented, and we studied the Er-Tm-co-doped silicon in cooperation with the correlative corporation, some results had been got and the further studies are carried...