The term photonic crystals appears because of the analogy between electron waves in crystals and the light waves in artificial periodic dielectric structures. During the recent years the investigation of one-, two-and three-dimensional periodic structures has attracted a widespread attention of the world optics community because of great potentiality of such structures in advanced applied optical fields. The interest in periodic structures has been stimulated by the fast development of semiconductor technology that now allows the fabrication of artificial structures, whose period is comparable with the wavelength of light in the visible and infrared ranges.

http://ieeexplore.ieee.org/iel5/6354/16969/00781867.pdf

Photonic crystals

Optical Solitons From Fibers To Photonic Crystals

We experimentally demonstrate a single sensor virtual ghost imaging (VGI) configuration that uses the physics of nearly diffraction free light sources to penetrate partially obscuring media or turbulent media and generate images of remote opaque objects. Randomly displaced nearly diffraction free Bessel beams provided improved illumination patterns for VGI and resolving small distant targets. VGI recovered the image of objects even when the coarse illuminating Bessel beam was transmitted through obscuring and turbulent media or through a small transversely displaced aperture. Bessel beam experiments are compared with Gaussian beam experiments under similar conditions.

Virtual ghost imaging through turbulence and obscurants using Bessel beam illumination

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Liquid Crystals Physical Properties And Nonlinear Optical Phenomena

Nonlinear Optical Properties of Liquid Crystals

Detailed and comparable investigations of the time evolution of the readout erasure of 1D
and 2D annular symmetry photonic lattice structures optically induced by nondiffracting
Bessel beam technique were performed. The lattices were recorded with the use of cw single
mode 532 nm, 17 mW laser beam in photorefractive LiNbO3:Fe and LiNbO3:Fe:Cu crystals, the latter
having also photochromic properties. While the 1D Bessel-like refractive lattice had
micrometric scale modulation in the radial direction, the 2D complex lattices inducted by
Bessel standing wave were a combination of annular and planar refractive gratings with
~10 μm period in the radial and
half-wavelength standing wave 266 nm period in the axial directions. The study of
photochromic properties of LN:Fe:Cu crystal at 532 nm showed 1.6 times increase of
absorption coefficient with increase of illuminating intensity from 12.5 to
96.8 mW/cm2,
which opened a direct way of essential decrease of the erasure of the stored lattices
during readout by weaker probe beam at the recording wavelength. Investigations showed
that the erasure constants for 1D and 2D lattices in LN:Fe:Cu crystal are larger than in
LN:Fe crystal (6150 and 5150 s, and 3080 and 698 s, respectively). The nondestructive
refractive lattices recorded by Bessel beam technique will assist the different
applications in all optical devices and communication systems and have particular interest
for experiments on light localization and spatial soliton formation in structured
nonlinear media.

Nondestructive readout of holograms recorded by Bessel beam technique in LiNbO3:Fe and LiNbO3:Fe:Cu crystals

Azimuthally modulated higher order rotationally symmetric Bessel-like optical patterns were generated by coherent superposition of two co-propagating Bessel beams – either in or out of phase. By changing the distance between the beam centers, a whole variety of transition states can be realized. As one prominent example, a 4-fold symmetry quadrupole-like photonic structure was optically inducted in an SBN crystal and nonlinear beam propagation in such a photonic wave-guiding structure is investigated in both self-focusing and self-defocusing regimes. The proposed device serves as an all-optical 2d 1 × 4 photonic interconnect.

Controlled soliton formation in tailored Bessel photonic lattices.

A novel counter-propagating Bessel beam technique is suggested and realized for optical formation of complex two-dimensional (2D) refractive lattice structures in photorefractive materials. The 2D complex lattices optically induced by the suggested method are a combination of annular and planar gratings with refractive index modulation in the radial direction in the transverse plane and the in axial direction along the optical beam propagation. The recording of the lattices is performed by 532 nm and 633 nm laser beams. The counter-propagating beam geometry builds up the Bessel standing wave with periodic annular structure in each anti-node. The refractive lattices are recorded in Z- and Y-cut 2 mm thick photorefractive lithium niobate crystals singly doped by Fe and doubly doped by Fe and Cu. The readout of recorded lattices is performed by Gaussian red and green probe laser beams. The direct observation of recorded lattices by optical phase microscope is also performed. The formed photonic structures ha...

Bessel standing wave technique for optical induction of complex refractive lattice structures in photorefractive materials

Optical induction of Bessel-like lattices in methyl-red doped liquid crystal cells

A counter-propagating Bessel beam technique is suggested and realized for creation of 2-dimensional (2D) holographic
periodic structures (PS) in photorefractive materials. 2D PS formed by the suggested method is a combination of
annular and planar gratings. The Bessel beam is formed by optical element - axicon. The recording of the gratings are
performed by single mode He-Ne laser beam at 633 nm. The counter-propagating beam geometry builds up the Bessel
standing wave with periodic annular structure in each anti-node. The refractive gratings are recorded in Z and Y-cut 2
mm thick Fe doped lithium niobate crystals via electro-optic effect. The read-out of 2D PS is performed by Gaussian
and Bessel beams. Diffraction patterns in transmission and reflection are observed. The formed 2D PS have the halfwavelength
standing wave period of ~300 nm in longitudinal direction, the period of ~10 μm in radial direction, and up
to 10 % diffraction efficiency.

Rafael Drampyan

Papers

Nondestructive readout of holograms recorded by Bessel beam technique in LiNbO3:Fe and LiNbO3:Fe:Cu crystals

Controlled soliton formation in tailored Bessel photonic lattices.

Bessel standing wave technique for optical induction of complex refractive lattice structures in photorefractive materials

Optical induction of Bessel-like lattices in methyl-red doped liquid crystal cells

New holographic method for formation of 2D gratings in photorefractive materials by Bessel standing wave