Pancharatnam-Berry Phase Optical Elements by use  of space-variant subwavelength gratings;

Geometrical Phase

Novel optical phase elements based on the space-domain Pancharatnam-Berry phase.

Unlike diffractive and refractive elements, the phase is not introduced through optical path differences, but results from the geometric phase that accompanies space-variant (transversely inhomogeneous) polarization manipulation. We show that such elements can be realized using computer generated space-variant subwavelength gratings. The elements are polarization dependent, thereby enabling multipurpose optical elements that are suitable for applications such as optical switching, optical interconnects and polarization beam splitting. Optical elements that use this effect to form a desired phase front are called Pancharatnam-Berry phase optical elements (PBOEs).

[1] Spiral phase elements obtained by use of discrete space-variant subwavelength gratings", A. Niv, G. Biener, V. Kleiner, and E.Hasman// Opt. Commun. 251, 306–314 (2005)

[2]Polarization dependent focusing lens by use of quantized Pancharatnam-Berry phase diffractive optics", E. Hasman, V. Kleiner, G. Biener, and   A. Niv // Appl. Phys. Lett. 82, 328-330 (2003)

[3] Space-variant Pancharatnam-Berry phase optical elements with computer-generated subwavelength gratings", Z. Bomzon, G.Biener, V. Kleiner, E. Hasman// Opt. Lett. 27, 1141-1143 (2002)

[4] Formation of Pancharatnam-Berry phase optical elements with space-variant subwavelength gratings", E. Hasman, V. Kleiner, G. Biener, and A. Niv, (Optics in 2002), OPN, Optics & Photonics News, 13, 45 (2002)

[5] Space-variant polarization-state manipulation with computer generated subwavelength gratings, Z.Bomzon, G. Biener, V.Kleiner, E. Hasman// (Optics in 2001), OPN, Optics & Photonics News, 12, 33 (2001)

Vectorial optical fields by use of subwavelength optics

We introduced and experimentally demonstrated propagation-invariant vectorial Bessel beams with linearly polarized axial symmetry based on quantized Pancharatnam-Berry phase optical elements (QPBOEs) and an axicon. QPBOEs utilize the geometric phase that accompanies space-variant polarization manipulations to achieve a desired phase modification. The obtained beam has a propeller-shaped intensity pattern that can be rotated by simple rotation of the polarizer.

[1] Propagation-invariant vectorial Bessel beams obtained by use of quantized Pancharatnam-Berry phase optical elements", A. Niv, G. Biener, V. Kleiner, and E. Hasman// Opt. Lett. 29, 238-240 (2004)

[2] Formation of linear polarized light with axial symmetry using space-variant subwavelength gratings", A. Niv, G. Biener, V.Kleiner, and E. Hasman // Opt. Lett. 28, 510-512 (2003)

[3] Formation of helical beams by use of Pancharatnam-Berry phase optical elements", G. Biener, A. Niv, V. Kleiner, and E. Hasman // Opt. Lett. 27, 1875-1877 (2002)

Polarization Encryption by use of  Pancharatnam-Berry Phase Optics

[2] Thermal image encryption obtained with a SiO₂ space-variant subwavelength grating supporting surface phonon-polaritons", N. Dahan, A. Niv, G. Biener, V. Kleiner, and E. Hasman// submitted to Opt. Lett. (2005)

Real - Time Polarimetry  by use of  space-variant subwavelength gratings

The DSGs are considered wave plates with constant retardation and space-variant fast axes. The formation of the grating is done by discrete orientation of the local subwavelength grooves. The complete polarization analysis of the incident beam is determined by spatial Fourier transform of the near-field intensity distribution transmitted through the discrete subwavelength dielectric grating followed by a subwavelength metal polarizer. Unlike other methods based on Fourier analysis, no active elements are required to determine the polarization state of an incident beam. Our method is suitable for real-time applications and can be used in compact configurations. It is possible to integrate our polarimeter on a two-dimensional detector array for lab-on chip applications to achieve a high-throughput and low-cost commercial polarimeter for biosensing.

[1] Spatial Fourier-transform polarimetry by use of space-variant subwavelength gratings", E. Hasman, G. Biener ,V. Kleiner, and A.Niv// (Optics in 2003), OPN, Optics & Photonics News, 14, No. 12, p. 34 (2003)

[2] Near-field Fourier transform polarimetry by use of a quantized space-variant subwavelength grating", G. Biener, A. Niv, V.Kleiner, and E. Hasman // JOSA A. 20, 1940-1948 (2003)

[3] Real-time analysis of partially polarized light with space-variant subwavelength dielectric grating",  Z. Bomzon, G. Biener, V.Kleiner, E. Hasman// Opt. Lett.  27, 188-190  (2002)

[4] Spatial Fourier-transform polarimetry using space-variant subwavelength metal stripe polarizers",  Z. Bomzon, G. Biener, V.Kleiner, E. Hasman// Opt. Lett.   26, 1711-1713  (2001)

Enchanced Thermal Emission by Surface Plasmon-Polariton and space-variant subwavelength gratings

We have demonstrated a narrow spectral relative emissivity peak for a broad range of observations for a SiO₂ grating. The enhanced thermal infrared radiation, which was obtained only with TM polarization, was attributed to the excitation of SPPs. Using the polarization dependence of the emissivity, a space-variant polarization manipulation of the thermal emission was experimentally demonstrated by controlling the local orientation of the subwavelength grating.

[2] Thermal image encryption obtained with a SiO₂ space-variant subwavelength grating supporting surface phonon-polaritons", N. Dahan, A. Niv, G. Biener, V. Kleiner, and E. Hasman// submitted to Opt. Lett. (2005)

3-D surface measurements

Transverse mode shaping and selection in laser resonators