Miniature circular polarization analyzer with spiral plasmonic lens

Abstract

A simple spiral plasmonic lens is studied both analytically and numerically. Owing to the geometric phase effect, a spiral plasmonic lens focuses the left-hand and right-hand circular polarizations into spatially separated plasmonic fields. Such a spatial multiplexing of the field distribution is utilized in miniature circular polarization analyzer design. A circular polarization extinction ratio better than 100 is obtainable with a device size as small as 4lambda(spp). The spiral plasmonic lens provides efficient plasmonic focusing while it eliminates the requirement of centering the incident beam to the plasmonic lens, making it suitable for full Stokes parameter polarimetric imaging applications.

Generating Far-Field Orbital Angular Momenta from Near-Field Optical Chirality

“…Currently, chiral nanostructures draw promising routes for enhancing singular optical signatures, thus providing extended control over new functionalities in metamaterial science [5] and biomimetics engineering [6,7]. Interestingly, while the connection between optics and chirality is well established for 3 dimensional (3D) chiral structures, the interaction of chiral light with 2D chiral objects is a topic of on-going debate [8][9][10], with strong potential in physical chemistry for chirality enhancement in the near field [11][12][13].Recently, singular optical effects have been discussed in the near field, in particular in relation to chiral surface plasmon (SP) modes which have been shown to carry orbital angular momentum (OAM) [14][15][16][17]. But until now, singular SP modes and associated spin-orbit coupling have only been probed in the near field [18][19][20].…”

Circular polarization analyzer with polarization tunable focusing of surface plasmon polaritons

“…That is, if the differential value is positive for the LCP light, then it will be negative for the RCP light. (2015) with previously reported CPAs, [19][20][21] an advantage of the proposed scheme is that the differential detection can suppress the noise of the incident light and enhance the sensitivity of the CPA. 23 The basic unit of the CPA consisted of two orthogonal slits which were arranged in a fishbone way and shown in the inset of Fig.…”

“…The extinction ratio was kind of low, but if we consider an area with a diameter of several k sp , it is still comparable to previously proposed CPAs based on a spiral lens. [19][20][21] Moreover, the extinction ratio can be improved by optimizing the parameters (w, l) of the slits and the arrangement (s, d) of the slits.…”

“…Depending on the vortex or focusing SPPs field distribution, circular polarization analyzers (CPAs), based on a spiral plasmonic lens, have been extensively studied. [19][20][21] However, the centers of both the vortex field and the focusing field coincide with the center of the spiral slit. Thus, it is difficult to place an optoelectronic detector in an area with a diameter less than one k sp (wavelength of SPPs) to detect the changes in the field distribution.…”

“…[8][9][10] Moreover, SPPs devices are sensitive to the polarization of the incident light as well. [11][12][13][14][15][16][17][18][19][20][21] The SPPs generated by a semicircular slit are focused in the center for light linearly polarized (LP) along the symmetry axis of the slit, whereas a split of the focus for the orthogonal linearly polarized light and the a transverse shift of the focus for the circularly polarized light can be observed. [11][12][13] In Ref.…”