Research On The Dispersion Compensation Thin Film Filter

In the generation of femtosecond laser pulse, the pulse would became broaden and exhibit chirp properties due to material dispersion and nonlinear effects; therefore a dispersion compensation device is required to counterbalance such adverse phenomena. Compared with prism pairs and grating pairs, optical thin film dispersive mirror manifest distinguished advantages, especially low insertion loss and high compensation precision.Nevertheless, there are still lots of challenge lie behind, including:difficulty in design when considering reflectivity and dispersion together; high sensitivity to fabrication error; lack of high-precision dispersion measurement device, etc.In order to overcome such difficulties, we made some advancement in design and measurement:(1).Employ and compare Different initial structure for dispersive mirror design; introduce particle swarm optimization as an alternative tool for optimization.(2). Analysis chirped properties and pulse broaden phenomena by Fourier method and wavelet transformation. Employ Finite-difference-time-domain for dynamic simulation of the pulse propagation process, also analysis laser damage properties based on this numerical method.(3).Build a white-light interferometer for precise phase measurement, some home-made dispersive mirrors are measured, and multiple numerical methods are employed to reduce the influence of measurement noise. This device also demonstrates potential in absolute phase measurement, thin film thickness retrieval and bulk material characterization.