We will report the new experimental results on MID femtosecond laser based on a multi-stage optical parametric amplifier, a new nonlinear crystal, SiC, was used for the three waves interaction. Comparative research with KTA crystal were also carried out. With optimized conditions, laser energy up to 520 μJ was obtained with central wavelength of 2.8 μm at 1kHz repetition rate. In this experiment, a home-made femtosecond Ti:sapphire laser system was used as pump laser. The seeding signal was introduced from the 3-mm YAG plate based white continuum and then pre-amplified in three non-collinear amplification stages. With 10-mJ pump energy in the last stage amplifier, laser energy up to 1.8 mJ for signal wave and 520 μJ for idler wave were obtained. Corresponding to a total conversion efficiency of 23.2% (signal plus idler). To maximize the bandwidth of the idler, a numerical model was developed to give an optimum non-collinear angle. As the result, the bandwidth as wide as 525 nm was realized, supporting 27 fs transform-limited pulse generation.
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