We have proposed an ultracompact all-optical photonic crystal AND gate based on nonlinear ring resonators, consisting of two Kerr nonlinear photonic crystal ring resonators inserted between three parallel line defects. We have employed a Si nanocrystal as the nonlinear material for its appropriate nonlinear properties. The gate has been simulated and analyzed by finite difference time domain and plane wave expansion methods. The proposed logic gate can operate with a bit rate of about 120 Gbits/s.

All-optical ultracompact photonic crystal AND gate based on nonlinear ring resonators

We present a simple and efficient method to generate any cylindrical vector vortex (CVV) beams based on two cascaded metasurfaces. The metasurface works as a space-variant Panchratnam-Berry phase element and can produce any desirable vortex phase and vector polarization. The first metasurface is used to switch the sign of topological charges associated with vortex, and the second metasurface is applied to manipulate the local polarization. This method allows us to simultaneously manipulate polarization and phase of the CVV beams.

Generation of cylindrical vector vortex beams by two cascaded metasurfaces

We propose theoretically and verify experimentally a method of combining a q-plate and a spiral phase plate to generate arbitrary vector vortex beams on a hybrid-order Poincare sphere. We demonstrate that a vector vortex beam can be decomposed into a vector beam and a vortex, whereby the generation can be realized by sequentially using a q-plate and a spiral phase plate. The generated vector beam, vortex, and vector vortex beam are verified and show good agreement with the prediction. Another advantage that should be pointed out is that the spiral phase plate and q-plate are both fabricated on silica substrates, suggesting the potential possibility to integrate the two structures on a single plate. Based on a compact method of transmissive-type transformation, our scheme may have potential applications in future integrated optical devices.

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Generation of arbitrary vector vortex beams on hybrid-order Poincaré sphere

We propose and experimentally demonstrate a novel interferometric approach to generate arbitrary cylindrical vector beams on the higher order Poincare sphere (HOPS). Our scheme is implemented by collinear superposition of two orthogonal circular polarizations with opposite topological charges. By modifying the amplitude and phase factors of the two beams, respectively, any desired vector beams on the HOPS with high tunability can be acquired. Our research provides a convenient way to evolve the polarization states in any path on the high order Poincare sphere.

Generation of arbitrary cylindrical vector beams on the higher order Poincaré sphere.

We propose and experimentally demonstrate a novel interferometric approach to generate arbitrary cylindrical vector beams on the higher order Poincare sphere. Our scheme is implemented by collinear superposition of two orthogonal circular polarizations with opposite topological charges. By modifying the amplitude and phase factors of the two beams, respectively, any desired vector beams on the higher order Poincare sphere with high tunability can be acquired. Our research provides a convenient way to evolve the polarization states in any path on the high order Poincare sphere.

Generation of arbitrary cylindrical vector beams on the higher order Poincare sphere

We have introduced a novel class of higher-order spatial optical Ince-Gaussian solitons (IGSs) that constitute the third complete family of exact and orthogonal soliton solutions of the Snyder-Mitchell model. The transverse structure of the IGSs is characterized by the Ince polynomials and has an inherent elliptical symmetry. The IGSs form the exact and continuous transition modes between Hermite-Gaussian solitons and Laguerre-Gaussian solitons.

Ince-Gaussian solitons in strongly nonlocal nonlinear media

Starting from the vector angular spectrum of the electromagnetic beam, the analytical vectorial structure of the radially polarized beams (RPBs) is presented. The energy flux distributions of the RPBs are demonstrated. The physical pictures of the RPBs are well illustrated from the vectorial structure. This particular electromagnetic field is entirely transverse magnetic, and on axis it only has a longitudinal (z) electric-field component (i.e., no transverse electric field and no magnetic field at all on axis).

Analytical vectorial structure of radially polarized light beams.

Based on the Snyder-Mitchell model in the Cartesian coordinate system, exact analytical Hermite-Gaussian (HG) solutions are obtained in strongly nonlocal nonlinear media. The comparisons of analytical solutions with numerical simulations of the nonlocal nonlinear Schrodinger equation show that the analytical HG solutions are in good agreement with the numerical simulations in the case of strong nonlocality. Furthermore, we demonstrate that HG functions can be expressed as a linear superposition of individual Gaussian functions with a π phase difference under the appropriate conditions.

Hermite-Gaussian breathers and solitons in strongly nonlocal nonlinear media

A radially polarized elegant beam (RPEB) in which the argument of the Laguerre part is complex is introduced and studied. The nonparaxial and paraxial propagation properties of the RPEB are demonstrated analytically and numerically in free space in terms of the vectorial Rayleigh-Sommerfeld formulas. The electric field distribution of the RPEB preserves the radial polarization at any propagation position. For the lowest-order RPEB and the lowest-order radially polarized beam cases, the general expressions for the nonparaxial propagation field are identical in free space. The exact on-axis expression of the RPEB has been provided in closed-form terms for an arbitrary transverse beam size.

Propagation of radially polarized elegant light beams

We have presented a novel family of paraxial laser beams, which are called Airy complex variable function Gaussian (ACVF-Gaussian) beams. The ACVF-Gaussian beams are formed by the product of an Airy complex variable function and a Gaussian function. Unlike Airy-Gaussian beams, which are nondiffracting, the ACVF-Gaussian beams, which have a rotating phase term are diffracting and rotating. The rotating velocity decreases when the propagation distance increases. We have analyzed the evolution of the Poynting vector and angular momentum density of the ACVF-Gaussian beams as they propagate in free space.

https://iopscience.iop.org/article/10.1088/1367-2630/11/10/103029/pdf

Qi Guo

Papers

Ince-Gaussian solitons in strongly nonlocal nonlinear media

Analytical vectorial structure of radially polarized light beams.

Hermite-Gaussian breathers and solitons in strongly nonlocal nonlinear media

Propagation of radially polarized elegant light beams

Airy complex variable function Gaussian beams