Gabriel Biener

Radially and azimuthally polarized beams generated by space-variant dielectric subwavelength gratings.

We present a novel method for forming radially and azimuthally polarized beams by using computer-generated subwavelength dielectric gratings. The elements were deposited upon GaAs substrates and produced beams with a polarization purity of 99.2% at a wavelength of 10.6 microm . We have verified the polarization properties with full space-variant polarization analysis and measurement, and we show that such beams have certain vortexlike properties and that they carry angular momentum.

Space-variant Pancharatnam–Berry phase optical elements with computer-generated subwavelength gratings

Space-variant Pancharatnam-Berry phase optical elements based on computer-generated subwavelength gratings are presented. By continuously controlling the local orientation and period of the grating we can achieve any desired phase element. We present a theoretical analysis and experimentally demonstrate a Pancharatnam-Berry phase-based diffraction grating for laser radiation at a wavelength of 10.6microm.

Polarization dependent focusing lens by use of quantized Pancharatnam–Berry phase diffractive optics

Quantized Pancharatnam–Berry phase diffractive optics using computer-generated space-variant subwavelength dielectric grating is presented. The formation of the geometrical phase is done by discrete orientation of the local subwavelength grating. We discuss a theoretical analysis and experimentally demonstrate a quantized geometrical blazed phase of polarization diffraction grating, as well as polarization dependent focusing lens for infrared radiation at wavelength 10.6 μm.

Formation of helical beams by use of Pancharatnam–Berry phase optical elements

Spiral phase elements with topological charges based on space-variant Pancharatnam-Berry phase optical elements are presented. Such elements can be achieved by use of continuous computer-generated space-variant subwavelength dielectric gratings. We present a theoretical analysis and experimentally demonstrate spiral geometrical phases for infrared radiation at a wavelength of 10.6microm .

Manipulation of the Pancharatnam phase in vectorial vortices.

Linearly polarized vectorial vortices are analyzed according to their Pancharatnam phase and experimentally demonstrated using a geometric phase element consisting of space-variant subwavelength gratings. It is shown that in the absence of a Pancharatnam phase, stable vectorial vortices that have no angular momentum arise. In contrast, if a Pancharatnam phase is present the vectorial vortices have orbital angular momentum and collapse upon propagation.

Polarization beam-splitters and optical switches based on space-variant computer-generated subwavelength quasi-periodic structures

Polarization beam-splitters and optical switches based on subwavelength quasi-periodic structures are presented. By locally controlling the orientation and period of the subwavelength grooves, birefringent elements for which the optical axes vary periodically, are realized. We present a theoretical discussion of these elements, as well as a detailed description of the design and realization procedures. We show experimental results for infra-red radiation at a wavelength of 10.6 μm.

Propagation-invariant vectorial Bessel beams obtained by use of quantized Pancharatnam-Berry phase optical elements

Propagation-invariant vectorial Bessel beams with linearly polarized axial symmetry based on quantized Pancharatnam-Berry phase optical elements are described. The geometric phase is formed through the use of discrete computer-generated space-variant subwavelength dielectric gratings. We have verified the polarization properties of our elements for laser radiation at 10.6-microm wavelength and also demonstrated propagation-invariant, controlled rotation of a propeller-shaped intensity pattern through the simple rotation of a polarizer.

Formation of linearly polarized light with axial symmetry by use of space-variant subwavelength gratings

We present a novel method for forming linearly polarized axially symmetric beams with various polarization orders that is based on computer-generated space-variant subwavelength gratings. We introduce and experimentally demonstrate that our space-variant polarization state manipulations are accompanied by a phase modification of a helical structure that results from the Pancharatnam-Berry phase. We have verified the polarization properties of our gratings for laser radiation at 10.6-microm wavelength.

Space-variant polarization manipulation of a thermal emission by a SiO2 subwavelength grating supporting surface phonon-polaritons

Space-variant polarization manipulation of thermal emission in a narrow spectral-peak is presented. The emission is attributed to surface phonon-polariton excitation from space-variant subwavelength SiO/sub 2/ gratings. We experimentally demonstrated thermal emission in an axially symmetric polarization distribution.

Highly coherent thermal emission obtained by plasmonic bandgap structures

We demonstrate an extraordinary quasimonochromatic thermal emission with high spatial coherence length (lc>2400λ) and a quality factor Q=2320 at radiation frequencies that are much smaller than the plasma frequency of metal (ω≪ωp). This emission is achieved by forming a plasmonic bandgap, which is obtained by a periodic structure on a metallic surface. Such a structure modifies the dynamics of the surface wave and results in a van Hove singularity [Van Hove, Phys. Rev. 89, 1189 (1953)] in the spectral density of states while maintaining a large coherence length.