Vectorial Modulation Research Articles

Flexible generation of the generalized vector vortex beams

We extend the existing vector vortex beams and demonstrate the creation of the generalized vector vortex beams, which is based on the superposition of any pair of orthogonal polarized base vectors with different spiral phases. Besides, we propose and experimentally demonstrate a flexible optical configuration, which modulates the generalized vector vortex beams through the phase-only liquid crystal spatial light modulators. Compared with the conventional vectorial modulation techniques, the explicit superposition and coaxial alignment of two laser beams are not required in our scheme. The theoretical derivation based on Jones matrix is demonstrated, and we experimentally verify the distribution of polarization and phase by measuring Stokes parameters and interference fringe, respectively. Such a proposed light field has potential applications in the domains as optical communication, nanoparticle manipulations.

Vector modulation instability in birefringent graded-index multimode fibers

We study vectorial modulation instability occurring inside a birefringent graded-index (GRIN) fiber when the two polarization components of the optical field are coupled nonlinearly through cross-phase modulation. In the scalar case in which only modes of one polarization are excited, the geometric parametric instability is known to produce an infinite number of sidebands around the wavelength of the input optical beam. We show that the birefringence of a GRIN fiber splits each of these sidebands into a triplet, whose frequency spacing depends on the differential group delay between the orthogonally polarized components. We verify the predictions of the linear stability analysis numerically by solving two coupled nonlinear Schrödinger equations that include spatial self-imaging effects through an effective nonlinear parameter. We present results for both continuous and pulsed optical beams experiencing normal or anomalous group-velocity dispersion inside a GRIN fiber.

Multi‐carrier transmission of vectorial modulation schemes using electronic transceivers at 588 GHz

A reported is presented on the first communication system using vectorial modulation schemes above 500 GHz. Using Schottky-based electronic technologies at 588 GHz, potentialities of high-level multi-carrier modulation schemes for wireless links are analysed. The wireless link is composed of an emitter with a sub-harmonic mixer for up-conversion from 294 to 588 GHz and carrier modulation. A pumped zero-bias detector is used at reception. Mono-carrier signalling is realised using an up to 32-symbol modulation scheme and multi-carrier terahertz transmission is also achieved using several modulation schemes in parallel.

Polarization mode dispersion and vectorial modulational instability in air–silica microstructure fiber

The birefringence of an air-silica microstructure fiber has been studied by measurement of the fiber polarization mode dispersion (PMD) over the wavelength range 545-640 nm. The experimental results are shown to be in good agreement with vectorial numerical calculations, assuming an elliptical core with an eccentricity of 7%. We also report controlled experiments studying nonlinear vectorial modulation instability in the fiber, yielding 3.9-THz modulational instability sideband shifts that are in good agreement with theoretical predictions based on the calculated fiber dispersion and PMD characteristics.

Vectorial diffraction patterns and limits of Brewster ellipsometry

A vectorial modulation transfer function approach of diffraction patterns observable around Brewster's incidence is proposed. The good agreement between experimental results and vectorial model will allow the correlation of refractive index measurement accuracy with the average magnitude of surface defects. Consequences in the metrology of refractive index gradients will then be briefly discussed.

Imaging with polarized light: the vectorial modulation transfer function of a polarizing plate

A vectorial modulation transfer function or spatial frequency response of optical imaging systems including linearly polarizing components is defined, calculated and compared to experimental results and to the classical scalar paraxial theory. This exact linear polarizer modulation transfer function calculus could be of particular interest in new ellipsometric measurement methods accuracy, especially for high resolution metrology and polarization imaging analysis.