提高能量密度的超衍射极限激光光束相位补偿技术

定义了激光光束衍射远场光斑压缩前后的能量比以及能量密度比来衡量超衍射极限激光光束的质量。通过利用反向传递算法设计了合适的补偿相位板，不但对准直放大的单一横模激光光束进行小于光学衍射极限的发散度的压缩，同时又保证光束能量集中于压缩后的远场衍射主瓣中，使压缩后的远场衍射光斑的能量密度增加。给出了相应的实例。这一结论不但解决了光学超分辨中光束压缩与能量损失不可避免这一矛盾，而且为发散度小且能量密度高的超衍射极限激光光束的实验工作以及该类光束的实际应用提供了理论基础。

The ratio of the power and the ratio of the power density are firstly defined to evaluate the quality of the beam beyond the diffraction limits. By use of the inverse transfer algorithm to calculate the phase distribution of an appropriate compensative phase, it is found that the reduction of the divergence of the laser beam beyond the diffraction limits and its power density of the diffraction central spot in the far field after reduction doesn't clearly decrease. This conclusion has more significances for practical applications of Gaussian beam beyond the diffraction limits in laser emitting optics. For the given intensity distribution in the far field with certain reduction ratio and limited energy loss, the reverse structure of phase plate could be calculated according to the inverse algorithms and the phase with continuous spatial distribution is quantified into step-shaped distribution so as to simplify the fabrication of a phase plate. This conclusion not only solves the contradiction of the reduction and the power loss, but also provides the theoretic basis for the experimental study and the practical application of the beam.