Study Of Slow Light Based On Erbium-doped Fiber Bragg Grating

As the rising volume of global communications and the limited computer data processing capacity, the requirement of AON (All Optical Network) and optical computer for people is strong so that slow light becomes pop research topic in recent years. When the velocity of the signal is decreased, the signal can be processed and stored conveniently, which would make the AON and optical computer come true. Recently, the method of using doped fiber Bragg grating to achieve an ultra-slow light is concerned particularly. This method can achieve different levels of changes in propagation velocity of signal to gain ultra-slow or ultra-fast light under different experiment conditions.The central wavelength of Erbium-doped fiber Bragg grating (EDFBG) is 1550nm, which can be used in real communication networks. Slow night based on EDFBG can provide signal delay for the optical buffer and optical storage technology. The doped ions in EDFBG are Er3+. The population inversion will occur between energy levels 4I15/2 and 4I13/2 of Er3+ under the action of pump with a certain frequency. Because the transitions between energy levels 4I15/2 and 4I13/2 make the EDFBG's relative refractive index change rapidly in a certain frequency, it will induce fast change of the probe propagation velocity when the signal getting through the EDFBG and gain ultra-slow or ultra-fast light finally.In this study, the expression of the transmission coefficient and group delay of the slow light based on EDFBG in theory are derived, and the numerical simulation to the results with mat lab is given,。We also get some important conclusions through the analyses and argumentation to the results.Fig.1 is the energy level diagram of Er3+ ions. The three-level system is made of energy levels4I15/2, 4I13/2 and 4I11/2. Under the action of pump with a wavelength of 980nm, the level 4I13/2 is populated via a fast decay from the level 4I11/2 so that the population inversion between levels 4I15/2 and 4I13/2 come out. The transition between levels 4I15/2 and 4I13/2 happens under the action of probe with a wavelength of 1533.8nm. Fig.1 The energy level diagram of Er3+ ions.The refractive index modulation of the EDFBG in this paper is n ( z ) = n0 [1 + 2 h cos(2πz / T+ ?)], 0