In the present communication, we describe how to produce long light distributions in the focal area of a high numerical aperture optical system using a custom modulation function with spiral charge. This analysis expands our previous developments in the field. We analyze the effect of this new element on the behavior of light along the optical axis.
In this work a new type of partially polarized and partially coherent sources is proposed. The coherence characteristics of these sources are dependent on the difference of the radial distances from the source center of the two points to be compared. The coherence is perfect for points located on the same circle centered on the source center and decreases for points that belongs to different concentric circles. The maximum attainable coherence is related to the degree of polarization of the source. Coherence and polarization characteristics of this kind of fields at the source plane and upon free space propagation are analyzed in detail for a simple case. For the particular presented example, a partially polarized and partially coherent field is obtained, whose polarization properties are invariant in propagation.
In this communication we analyze the light field distribution of a highly focused radially polarized beam when passes through a linear polarizer. The polarizer is modeled as a plane-parallel uniaxial absorbing medium with the optical axis parallel to the plate surfaces of the polarizer. Analytical results and numerical calculations are provided.
Dark plasmon modes in metal nanoparticle systems are usually excited by non-optical means. We show that strongly focused illumination can lead to excitation of dark modes. We first use rigorous vectorial diffraction theory to compute the distribution of light at the focus and then numerically calculate the response of single particles and particle dimers. Controlling the distribution of light arriving at the focusing lens by pupil filters enables enhancing the excitation of dark modes. Overall, these results present guidelines for the excitation of dark plasmon modes using standard optical instrumentation.
The target of this communication is to present a method for tailoring the complex amplitude and the polarization at the entrance pupil of a high numerical aperture objective lens in order to obtain focused fields with transverse circular polarization at any plane. Analytical expressions within the framework of the Richards-Wolf vectorial model are derived and some numerical results are presented.
A method for generating beams with arbitrary polarization and shape is proposed. Our design requires the use of
a Mach-Zehnder set-up combined with translucent liquid crystal displays in each arm of the interferometer; in this
way, independent manipulation of each transverse beam components is possible. The target of this communication
is to develop a numerical procedure for calculating the holograms required for dynamically encode any amplitude
value and polarization state in each point of the wavefront. Several examples demonstrating the capabilities of
the method are provided.
Recently, the development of optical setups capable of generating beams with arbitrary polarization have attracted
broad interest. One possible way to implement such devices is by taking advantage of the properties
of liquid crystal spatial light modulators, which act as optical phase retarders controlled by computer. In this
communication we present the design of an alternative experimental setup for the generation of light beams
with arbitrary spatially-variant polarization distribution. The objective is to develop a flexible optical device
capable of dynamically encode any elliptical polarization state in each point of the wavefront. Our approach is
based on a Mach-Zehnder setup combined with a translucent modulator in each path of the interferometer. The
transverse beam components of the incident light beam are processed independently, and modified by means of
their respective modulator displaying a specifically tailored computer generated phase hologram.