Dipolar and symmetrical heptamethine dyes featuring strong linear absorption in the near-infrared spectral range (700−900 nm) were prepared at a gram scale. X-ray crystallographic structure of dipolar chromophore is described revealing remarkable planarity polyenic chain due to central ring molecule. These chromophores present promising nonlinear properties telecommunication wavelengths (1400−1600 nm): (i) significant two-photon cross-sections measured using femtosecond Z-scan method, (ii)...

We describe the programmable spatial beam shaping of 100-kHz, 4-microJ amplified femtosecond pulses in a focal plane by wave-front modulation. Phase distributions are determined numerical iterative procedure. A nonpixelated optically addressed liquid-crystal light valve is used as tailoring device. Top-hat, doughnut, square, and triangle shapes 20-microm size obtained plane. Their suitability for laser machining demonstrated.

A new two-wave-mixing interaction with gain through a Bi12SiO20 liquid-crystal light valve is presented. We show that the diffraction of pump beam in direction weak signal leads to net amplification beam, no need for phase shift between interference pattern and induced index grating. 10 150-ms response time are obtained 8.8-µm-thick layer, total intensity interacting beams only 200 µW/cm2, an ac external voltage ±6 V. Image also demonstrated.

In the paraxial Debye regime, simple and power-efficient pupil filters are designed to break diffraction limit along a large depth of focus (DOF) for Gaussian beam. Dependences superresolution factor, DOF gain, Strehl ratio, sidelobe strength, axial intensity nonuniformity on profile in plane characterized using numerical method. Optimal filter designs proposed either high-resolution or ultra-large-DOF applications followed by experimental verifications.

By exploiting the highly chromatic behavior of semiconductor structures with mesoscopic dimensions only slightly smaller than wavelength, efficient diffraction is maintained over almost one octave.

The bandwidth demands in mobile communication systems are growing exponentially day by as the number of users has increased drastically over last five years. This data explosion, together with fixed service limitations, requires a new approach to support this increase demand. Solutions based on lower-frequency microwave wireless may be able meet demand short term. However, small-cell mass deployment requiring total capacities 1 Gb/s/km <sup xmlns:mml="http://www.w3.org/1998/Math/MathML"...

A fully 3-D-printed wideband metamaterial absorber, characterized by an absorptivity above 0.95 in the X and Ku-bands with a fractional bandwidth of 0.71, is presented this letter. 250 mm × sample, total thickness 6.3 (0.26λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ), fabricated exploiting fused deposition modeling technique commercial filaments. To achieve absorption, hyperbolic pyramidal shape designed vertically stacking...

This paper presents a 2D-beam-steering antenna for Satcom applications based on simplified Risley scanner, which consists of leaky-wave feed and single deflector fabricated by additive manufacturing. Such configuration simplifies classical scanners, where source illuminates combination two prisms. The pointing direction the radiated beam is controlled relative azimuthal positions between deflector. comprises modulated metasurface fed quasi-optical system to maximize its aperture efficiency....

This letter presents a new type of metasurface, which consists checkerboard-type layout, made electrically small complementary metallic patches and apertures. Depending on whether the patches' vertices are interconnected or not, structure may not support propagating quasi-TEM mode. feature offers possibility designing arbitrary transmission line paths checkerboard metasurface (CBMS) by dynamically changing vertex connections. An equivalent network model is proposed for CBMS validated through...

Thanks to the growing development of printable materials dedicated microwave applications, 3D printing technology is bringing new opportunities RF engineering. In this paper, a fully 3D-printed metasurface absorber with pyramidal shape and operating in wide frequency band 7.6-17.4 GHz was designed, fabricated using FDM method, characterized. The proposed structure permits absorption more than 90% energy an impinging electromagnetic wave normal incidence. measurement setup validated on...

We report a new nearly degenerate two-wave mixing interaction in photorefractive Bi12SiO20 crystals which the signal beam is time modulated at high frequency. The coupling phenomena and integration properties of crystal allow us to achieve differential gain γdiff on transmitted beam. dependence versus duty cycle analyzed. Amplification regeneration periodic, or random sequences information bits are experimentally demonstrated.

An external cavity with a binary phase grating has been developed to achieve the coherent beam addition of five quantum-cascade lasers emitting at 4.65 μm. The combining these emitters is achieved by or Dammann able separate an incident into beams equal intensities 75% efficiency. A CW output power ~ 0.65 W corresponding efficiency 70% good quality obtained. More results concerning power, combining, stability and spectrum are exposed.

In this letter, the performance of a diffractive gradient index lens antenna, constructed by using dielectric subwavelength structuration and manufactured three-dimensional printing, is compared to ones conventional antennas in small footprint configuration. It discusses advantages drawbacks each configuration compares simulated measured gain performances. shows that structured antenna can achieve superior approaches, combined with 1 dB bandwidth 10.9%, thanks engineering artificial index....

We demonstrate correction of laser wave-front distortions by use an adaptive-optical technique based on a light valve. The setup consists achromatic and adjustable-sensitivity sensor corrector relying optically addressed liquid-crystal spatial modulator. Experimental results with strongly aberrated beams focused close to the diffraction limit are presented for cw regime. Additional experiments pulses measurement damage thresholds show that this approach is relevant phase ultraintense pulses.

A complete real-time cross-correlator using both a photoconductive bismuth silicon oxide [Bi12Si020 (BSO)] liquid crystal light valve for data input and photorefractive BSO as dynamic holographic filter is presented. Some specific properties of this optical processor are reported. The following optimum operating conditions the were used in experiment: driving voltages, 30 Vrms; frequency, 300 Hz; writing energy blue-green spectral range, 150 /uJ cm -2. For 15µm thick pentylcyanobiphenyl...

We consider optimization of hybrid imaging systems including a pupil mask for enhancing the depth field and digital deconvolution step. In previous paper [Opt. Lett. 34, 2970 (2009)] we proposed an criterion based on signal-to-noise ratio restored image. use this in order to optimize different families phase or amplitude masks compare them, objective basis, desired defocus ranges. show that increasing number parameters allows one obtain better performance.

We present a new beam-shaping technique with an intracavity optically addressed liquid-crystal spatial light modulator. The Nd:YAG resonator is able to deliver beams various profiles such as flat-topped super-Gaussian and square-shaped beams.

Interest in utilizing additive manufacturing for RF applications has increased remarkably recent years thanks to the potential producing complex and lightweight parts, as well reducing costs processes. However, materials available 3D-printing are not developed microwave thus do have required properties applications. In this paper, we present a new composite material based on COC (Cyclic Olefin Copolymer) polymer loaded by titanium oxide (TiO <sup...

A new hybrid method for the analysis of diffractive optical elements, which combines fully vectorial and scalar theories, is presented. It suitable use with elements arbitrary large zone, even when local feature size order wavelength. To assess its applicability, we have performed cross-checking tests. The model shown to accurately predict many properties based on two-dimensional artificial dielectrics, like useful energy diffracted into interest or deterministic loss high diffraction orders...

Imaging systems that combine a phase mask in the pupil and digital postprocessing may have better performance than conventional ones. We built such system to enhance depth of field an uncooled thermal camera. The masks are binary, their structures optimized thanks image quality criterion, they been realized with three different technologies give equivalent results. deconvolution is performed real time graphics processing unit. A significant increase factor 3 has obtained.

Increasing the depth of field (DOF) compact visible high resolution cameras while maintaining imaging performance in DOF range is crucial for such applications as night vision goggles or industrial inspection. In this paper, we present end-to-end design and experimental validation an extended depth-of-field High Definition camera with a very small f -number, combining six-ring pyramidal phase mask aperture stop lens digital deconvolution. The deconvolution algorithm are jointly optimized...

This article presents a large-aperture flat off-axis lens operating in the Ka-band around 30 GHz and fully 3D-printed by FDM (Fused Deposition Modelling) technique with high-permittivity dielectric material. The refractive index profile, which is required to transform spherical wave into tilted plane wave, implemented structuring material at sub-wavelength scale. fabricated 460mmdiameter composed of 20 000 circular pillars whose diameter varies from 0.8 mm 2.6 mm. To best our knowledge, this...

Projection systems based on liquid-crystal displays (LCD's) offer new opportunities to display high-definition and large-size TV images. There are two types of LCD projector architectures: the 3-LCD architecture uses one for each primary color, red, green, blue, whereas a single-LCD configuration employs only paved with color filters. The is simple compact but suffers from poor luminous efficiency because losses in filters: filter transmits ~1/3 flux emitted by lamp. To increase this optical...