Study On Ultrashort Optical Pulse Shaping

In many areas, the picosecond and femtosecond pulses had attracted considerable attention. The input pulse generated by the mode-locked laser to Sech2 or Gaussian pulse in some special system. But this method can not get a good application.Firstly, the ultrashort optical pulse shaper was studied in this article. Several methods the pulse shaper were listed and compared in recent years, for example AWG, F-P, M-Z and Fiber gratings et al. Then by introducing the preparation methods, application areas and research methods of fiber gratings, it provided a good theoretical basis for the following.Secondly, Fiber Grating was analyzed. Phase points in an amount of 0,1 and 2 points were added at the average length of the Fiber grating. When the mount of the phase shift point was zero, the transmission windows and the phase jumps were zero on the reflection spectrum. When the mount of the phase shift point was one, the transmission windows were one on the reflection spectrum. When the mount of the phase shift points were two, the transmission windows were two on the reflection spectrum. The phase jumped. By change the length of the grating, the length ratio about the first and second sections grating, the phase, the reflection spectrum characteristic of the fiber grating were changed.Finally, differential effects were proved about the phase-shifted fiber grating. By using the differential effects of phase-shifted fiber grating, the Gaussian pulses were inserted into the phase shift grating, the shapes of the output pulse could be formed to rectangular and triangular. However, by improving the performance of the waveform using one, two, three, four differentiator, the pulse shaper was designed based on the characteristics of the differential phase shift grating. By optimizing the weighting factors for each order derivative of a Gaussian input pulse, the output pulse can be formed to rectangular and triangular. At the same time, the stability and practicality of the pulse shaping system were verified.