JEOS:RP - Journal of the European Optical Society Rapid publications
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Electrically tunable, ultranarrowband, circular-polarization rejection filters with electro-optic structurally chiral materials
Full text linkThe transmittance spectrum of a slab of an electro--optic structurally chiral material (SCM) that is helicoidally
nonhomogeneous in the thickness direction and is endowed
with a central 90--twist defect, shows evidence of an ultranarrowband spectral hole when a sufficiently high dc electric field is applied between the entry and the exit planes and the incident light is circularly polarized in opposition to the structural handedness of the SCM. This spectral hole migrates on the wavelength axis as the applied dc electric field is altered in magnitude, thereby suggesting the possible use of a centrally defective, electro-optic SCM slab as an electrically tunable, circular-polarization rejection filter with ultranarrow bandwidth
Mesoscopic magnetism in dielectric photonic crystal meta materials: topology and inhomogeneous broadening
Full text linkWe consider meta materials made from a two-dimensional dielectric rod-type photonic crystal. The magnetic response is studied within the recently developed homogenization
theory and we in particular study the effects of topology and inhomogeneous broadening. While topology itself mainly affects the Mie resonance frequency we find that the
dispersion in the topological radius R of the dielectric rods may lead to significant inhomogeneous broadening and suppression of the negative-mu phenomena for dR/R
High-NA aberration retrieval with the extended Nijboer-Zernike vector diffraction theory
Full text linkThe reconstruction of the exit pupil function of an optical system can basically be carried out by collecting intensity data in the focal region from a certain number of defocused image planes. In this paper we present the first results of such a reconstruction operation for optical systems with a high numerical aperture using a point source in the object plane. The main feature of our approach is the use of the extended Nijboer-Zernike diffraction analysis that has been modified to incorporate vector diffraction effects. The quality of the optical system is expressed by means of a set of complex Zernike coefficients that describe the phase and transmission variation in the exit pupil of the imaging system. The ’vector’ method will be compared to the more common scalar diffraction analysis. We also analyse the practical limits of the vector retrieval process regarding the maximum allowed aberration and the noise of the intensity data. The sensitivity of the method with respect to parameter settings (state of polarisation and value of numerical aperture) is also examined
Multi-kernel deconvolution applied to confocal fluorescence microscopy with engineered point spread function
Full text linkFluorescence microscopy is a powerful technique in biology, because of the immense variety of markers now available. Compared to other methods, its resolution is however limited. In wide-field microscopy, the technique of structured illumination permits to improve the lateral resolution by a factor of two, even surpassing confocal microscopy, which permits a theoretical gain of about 40%. We propose an alternate technique, combining laterally interfering focused beams, which should permit the same gain of resolution in a confocal microscope. Furthermore, this technique, combined with multiple acquisition and multikernel deconvolution, permits a better object reconstruction than classical monokernel deconvolution using a regular excitation point spread function
Inversion of a guided optical vortex
Full text linkWe demonstrate, both theoretically and experimentally, the inversion of the topological charge of a vortex that propagates through an optical fiber. In our experiment, we couple the vortex to a two-mode fiber and we control the charge inversion by deformation of the optical fiber