优化设计了高功率、高效率掺铒光纤超荧光光源的参数。采用商用掺铒光纤，针对双程后向结构，首先仿真了光源输出功率和带宽随掺铒光纤长度的变化，并用对等实验验证了模拟结果，初步确定掺铒光纤长度的优化范围；理论研究了反射镜反射率对光源性能的影响，计算出最佳反射率并模拟了该反射率下光源的输出光谱；实验研究了抽运功率对光源平均波长的影响，确定了优化的抽运功率范围，并进一步确定了掺铒光纤的优化长度。实验选用110 mW抽运功率，13.74 m掺铒光纤，获得了输出功率为46.9 mW 的高功率光纤光源，其抽运转换效率可达42.6%，且光源保持了约34.54 nm的宽带宽。

A rotation, scaling, and translation invariant local watermarking is proposed with one or two Krawtchouk moment(s) of the original to estimate the geometric distortion parameters including rotation angle, scaling factor, and translation parameter. Krawtchouk moments can be used as private key of watermark extractor. Watermark is inserted into perceptually significant Krawtchouk moments of original, and watermark based on Krawtchouk moments is local. Independent component analysis (ICA) is utilized to extract watermark blindly. Experimental results show that this method has a good robustness against distortions preformed by watermark benchmark -- Stirmark.