Manipulating And Focusing Of The Vectorial Field In The Broad Band

Vectorial field is the special optical field with space-variant polarized states. For the unique polarization property, it has attracted a great deal of attention in the world. As an important laser source, this field has been considered as the candidate for the optical super-resolution imaging, micro-nano manipulating, laser machining and so on. Based on the diffraction integral theory of the vectorial field, here the pupil filter is designed optimally to satisfy a request for the manipulating and focusing of the vectorial field in the broad band.Based on the achromatic principle of composite wave plate, a pupil filter is presented for the focusing of the broadband vectorial field with the center wavelength 600 nm. This filter is combined of three segmented wave plates. And each of them is divided into four concentric belts with optimized radial parameters and azimuth angle. The optical axis of the two adjacent belts is vertical. For the incident vectorial beam with wavelength 550nm~650nm, the desired special focused field with extended depth of focus, such as needle field with compressed radial width and diffraction-limited tube filed, can be achieved. The result shows that this filter can be effectively used as an effective manipulator for the vector beam with wide waveband in the 100 nm band. This achromatic pupil filter will be beneficial for the development of the focusing theory and applied technology about the wideband vectorial field.Utilizing the diffraction integral theory of vector field and the pupil filtering method with discrete complex amplitude, we presented a tunable complex amplitude filter with six-ring belt to tailor the polarization, amplitude and phase of the incident vectorial field in the wide band(30nm). With optimized cylindrical polarization(o520j=) and discrete amplitude, the generalized cylindrical vector field can be tightly focused into a three-dimensional(3D) flat-top field with extended depth of focus(~10?) by the high numerical aperture(NA) lens. For the main outermost zone and the other five inner zones, we analyzed the intensity distributions of the three polarized components and the total polarized components in the focal region. We found that axially and azimuthally polarized components are the major contributors. The outermost zone offers the central field of the focused field while the other five zones affect the side lobe more obviously. Through adjusting the included angle ? of the double wave plates, we can change the polarization states of incident vector field and alter the structures of the focused fields among the 3D flat-top focused field, needle-like field, tube-like field and the other field with intermediate form. The result is superior to the past research for its adjustable freedom between these forms and it reveals the dynamic relation between the evolved vectorial form of incident field and the vector structure of the focused field. Our work paves a way to achieve the controlled dynamical focused field with long depth of focus. The needle-like field, tube-like filed and the well-matched 3D flat-top focused field will meet applications in optical microscope, optical micro-manipulating, optical micromachining and so on.