Polarization and amplitude hybrid modulation of longitudinally polarized subwavelength-sized optical needle

We present a method of both polarization and amplitude modulations on an incident beam to obtain a longitudinally polarized subwavelength-sized optical needle.A 4-f system with a spatial light modulator is used to generate experimentally a two-mode alternate cylindrical vector beam by polarization modulation,enhancing performance and facilitating implementation.We optimize the beam focusing properties after passing the beam through an annular aperture to obtain amplitude modulation by the simulated annealing algorithm.Numerical results indicate that a sharp focal spot(0.417λ) with a long focal depth(8λ) and a strong longitudinally polarized field can be easily achieved.     

测量任意波片相位延迟量的简便方法

为了更方便的测量待测波片的相位延迟量,提出了简便易行的测量任意波片相位延迟量的方法,无需标准1/4波片,而且还可以利用一套实验系统同时测量2个未知波片的相位延迟量,并从理论上推导出了通用测量公式,从实验上进行了实际测量.