This paper presents a novel technique for dispersion compensation, employing a linear chirped fiber Bragg grating (CFBG) with a thermal head consisting of several micro-heaters. The micro-heaters temperature are controlled by computer, and the change of micro-heaters temperature will induce the change of grating temperature, and the change of Bragg wavelength, and the change of delay and dispersion of the grating. Thereby, the goal of tunable dispersion compensation to different systems dispersion and the survival dispersion has been achieved.
In this paper, the amplification mechanism of ultra-wide-band telluride-based fiber Raman amplifier (T-FRA) is described, and the Raman gain coefficient spectra of telluride-based fiber are studied thoroughly by compare the stimulated Raman scattering (SRS) characteristics of the telluride-based fiber with silica-based fibers. First, the cooperation of phonons and photons in telluride-based fibers is analyzed. Then the reason why Raman scattering of the telluride-based fibers can lead to a large gain coefficient and Stokes shift is discussed. The physical basis is analyzed in this paper and the energy of molecular vibration is taken into account. A multi-pumping scheme is provided at the end of the paper to apply gain-flattened T-FRA to WDM system.
In this paper, we present a new numerical method for calculating pump power in designing multi-wavelength pumped Raman amplifiers, by using some optimal searching method, we establish a complete computing model to optimize the pump wavelength and power allocation with flat net gain and broad bandwidth. In order to increase precision and degrade computing time a new predictor-corrector linear multistep method is proposed instead of one-step method, which was adopted in traditional designing to calculate power integral for signals and pumps propagating through the fiber. Further more, we adopt the Quasi-Newton iteration method to adjust the pump power efficiently without any manual adjustment. The optimal results show that by using our method, iteration process will be convergent rapidly and relative gain flatness below 5% can be achieved over 100nm bandwidth without any gain equalization devices. The whole optimal method costs within 10 minutes in a common computer.
An experimental setup was established by using a high stability, narrow line bandwidth fiber laser with a fiber optic amplifier, polarization maintaining fiber coupler with split ratio of 50:50 and 95:5 respectively, a fiber optic sensing coil with high birefringence large nonlinear polarization maintaining fiber, and uniform fiber Bragg grating that was used at output port for filtering the excess pumping component. Based on this experimental setup, the threshold power of the pumping laser was deduced, and the relationship of the spectra and intensity between pumping laser component and stokes component with frequency downshift was obtained experimentally.