Plane Light Wave Research Articles

Twin Photonic Hooks Generated by Twin-Ellipse Microcylinder

Recently, two special photonic jets, photonic hooks and twin photonic jets, have been proposed to deal with complex conditions in nanoscale manipulation. Photonic hooks are generated by a single light plane wave and an asymmetric microparticle, while the twin photonic jets are produced by two incident light beams. In this letter, we presented and demonstrated a method to combine photonic hooks and twin photonic jets. A single light plane wave and a symmetric microparticle, twin-ellipse microcylinder, are used in this research. The curvature degree, length and maximum E 2 field enhancement of twin photonic hooks are varied significantly, with the change of refractive indices and shape of twin-ellipse microcylinder. And a liquid-immersed core-shell is built to achieve a flexible tunability.

Plasmonic properties of a honeycomb structure formed by metallic nanoparticles

Abstract This work reports on a study regarding the plasmonic properties of a honeycomb-like structure that is formed by silver and gold nanoparticles. A honeycomb structure is proposed, and its plasmonic characteristics under the irradiation of a plane-wave light are numerically calculated, with several parameters being varied, including the radius of the nanoparticles, the separation between adjacent nanoparticles, and the polarization of the incident light. In the honeycomb, highly localized electric fields created by the oscillation of surface electrons are observed, and the associated electromagnetic hot spots are revealed in the vicinity of the noble metals. The results demonstrate that localized electric fields can be generated in the honeycomb-like structure, due to the plasmonic coupling between the metallic nanoparticles, and the hot spots can be adjusted by varying the values of the nanoparticles’ radius, the separation, as well as the incident light’s polarization. The plasmonic characteristics of the metal–nanoparticle honeycomb structure revealed in this study may be useful in the designs of plasmonic devices that utilizes localized, intensive electromagnetic hot spots.

Dual-wavelength plasmonic perfect absorber suitable for refractive index sensing

In this paper, a plasmonic perfect absorber (PPA) based on metal-insulator-metal-insulator-metal (MIMIM) structure has been designed for refractive index sensing of glucose solutions (analyte) and then a new method has been proposed for fast, low-cost, and easy measurement of sensor’s sensitivity. Simulation results show that the absorption spectrum of the proposed sensor has two resonance peaks that with an increase in analyte refractive index, both of them are red-shifted. In our proposed measurement technique, two conventional single-wavelength lasers (with wavelengths of 1050 nm and 1750 nm) are used for vertical plane wave light illumination on the structure. Then, the absorbed powers at 1750 nm (A2) and 1050 nm (A1) wavelengths are calculated and variation of the absorption ratio (A2/A1) due to change of analyte refractive index would be introduced as the sensitivity of sensor (S = Δ(A2/A1)/Δn). Obtained results show that the increase of analyte refractive index from n = 1.312 to n = 1.384 will result in an increase of sensor’s sensitivity from 9.3/RIU to 33.475/RIU.

Kramers-Heisenberg dispersion formula for scattering of twisted light

An extremely active research topic of modern optics is studying how light can be engineered to possess forms of structure such as a twisting or a helical phase and the ensuing optical orbital angular momentum (OAM) and its interactions with matter. In such circumstances, the plane-wave description no longer suffices and both paraxial and nonparaxial solutions to the wave equation are desired. Within the framework of molecular QED theory, a general formulation is developed for the scattering of twisted light beams by molecular systems through the Kramers-Heisenberg dispersion formula and ensuing scattering cross section, which takes account of the effects of the phase and intensity structure of twisted light, revealing scattering effects not exhibited by unstructured, plane-wave light. The theory is applicable to linear scattering as well as to nonlinear optical effects for both chiral and nonchiral species, and explicit results are derived for Rayleigh and Raman scattering (including second-order contributions), Rayleigh and Raman optical activity, and their circular-vortex differential scattering analogs. These processes necessitate the inclusion of magnetic-dipole and electric-quadrupole coupling terms, as well as the usual leading electric-dipole interaction term. It is seen that the coupling of electric quadrupole moments to structured light affords a unique sensitivity to the phase properties of the beam, most importantly, its optical OAM, and its inclusion permits the contribution to the scattering cross section proportional to the square of the mixed electric dipole-quadrupole polarizability to be evaluated for which interesting features result. These include its discriminatory behavior arising from circularly polarized input radiation and its dependence on the topological charge, which can also serve to enhance scattering. Also presented are results for a contribution of identical order proportional to the pure electric-dipole and quadrupole polarizabilities.

Influence of turbulence structure with different scale on aero-optics induced by supersonic turbulent boundary layer

Studying the effects of turbulent structure with different scale on aero-optics is of great significance to improve the accuracy of wavefront measurement and simulation, and to guide the suppression of aero-optics through large eddy breakup. Based on the high-spatial resolution (11.4 μm/pixel) density field of the supersonic (M∞ = 3.0) turbulent boundary layer (SPTBL) obtained by Nano-tracer-based planar laser scattering (NPLS) technique, the curvelet transformation is used to extract the density field at a specific turbulence scale. The statistical results of the propagation of Gaussian plane light wave in the corresponding density field at different turbulence scales are calculated. The smaller the scale of turbulence structure is, the less contribution it makes to aero-optical distortion. The fully developed SPTBL has less effect on the beam center offset (x¯), but more obvious effect on the beam spread about the center (x'2¯). x¯ is mainly caused by the turbulent structure with relatively large scale (turbulence characteristic length scale Lj>δ), while the contribution of large-scale structure to the x'2¯ is not significant. The x'2¯ is mainly caused by the turbulent structure with relatively small size (Lj≈0.13δ) in the flow field. The smaller scale (Lj<0.94θ) turbulence structure has less influence on the x¯ and x'2¯. θ can be also used as a validation index of aero-optical effective scale.

Generation of superposition modes by polarization-phase coupling in a cylindrical vector orbital angular momentum beam

Polarization and spatial phase are independent characteristics for the linearly-polarized plane light wave. These characteristics can be coupled when the light field has an inhomogeneous polarization state in space and time. Inhomogeneous polarization appears in the vector beam. The polarization-phase coupling takes place by introducing the orbital angular momentum to the vector beam. In this paper, the polarization-phase coupling in the vector orbital angular momentum beam has been examined. The polarization-phase coupling induces Laguerre-Gaussian modes with different orders, and the resultant electric field is a superposition of induced Laguerre-Gaussian modes. The analytical expressions for the resultant electric fields have been derived under the paraxial approximation and confirmed by numerical calculation.

The angular momentum of an isotropic cholesteric liquid crystal induced by a plane elliptically polarized wave near the phase transition temperature

The interaction of an elliptically polarized plane light wave with a cholesteric liquid crystal in the isotropic phase within the pretransition temperature range has been considered. The density vector of the light wave angular momentum has been shown to change periodically with the propagation coordinate. The dependence of the acquired by the medium angular momentum on the length of the cholesteric liquid crystal cuvette has been found.

Light propagation in and outside a sphere illuminated by plane waves of light

Light propagation in and outside a sphere illuminated by plane waves of light

Prediction of resonant frequencies of a dual-wavelength plasmonic perfect absorber as a sensor by resistor–inductor–capacitor circuit models

A plasmonic perfect absorber (PPA) based on a metal–insulator–metal–insulator–metal structure has been designed for refractive index sensing of glucose solutions (analyte). Then resistor–inductor–capacitor equivalent circuit models based on dimensions, the position of the components, and materials used in the structure have been developed to predict resonance frequencies of the absorber. Simulation results show that in the perpendicular incidence of a plane wave of light within 5 to 9 μm wavelengths, for the analyte placed over sensor surface with a refractive index of n = 1.312; the output absorption spectrum of the device has two resonance peaks, respectively, on λ1 = 6441.01 nm and λ2 = 7909.74 nm wavelengths. When the refractive index of analyte increases to n = 1.384, both resonant peaks are red shifted. Sensitivities (S = Δλ / Δn) of the first and second resonance peaks have been obtained as S1 = 1287.083 nm / RIU and S2 = 1142.5 nm / RIU, respectively.

An infrared narrow-band plasmonic perfect absorber as a sensor

In this paper, we propose a nanoscale Infrared Plasmonic Perfect Absorber (IPPA) based on Metal-Insulator-Metal (MIM) structure with two different nano- apertures in the upper metal layer for sensing the refractive index of liquids (analyte), and use the 3D FDTD numerical method in order to obtain the absorption spectrum of each structure for perpendicular incidence of a plane wave light within 1500–1850 nm wavelength range. Simulation results show that, a resonance peak is obtained in each spectrum. When the analyte refractive index increases, the resonance peak have a red shift. Once, in nano-aperture design by rectangular branches, FWHM and Figure of Merit (FOM) of resonance peak were obtained, 89.50 and 2.91, respectively. Also, in nano-aperture design by sharp tip triangular branches, FWHM and FOM of resonance peak were obtained, 57.98 and 3.04, respectively. The analysis of electromagnetic fields show that, the field localization at the tips of the aperture branches increases, and the bandwidth of the resonance peak is reduced. Hence, the achieved FOMs are very suitable for different liquids sensing with refractive indices close to each other in a narrow-band spectral range.

Study the Acousto-Optic Spatial Filters Diffracted Light at Zeroth-Order Using MATLAB

This paper introduces the essentials of acousto-optics with the theory and applications using MATLAB. There are some software used to process acousto-optics filter and the implementation details of any acousto-optics algorithm are inaccessible. Our work is focused on software used to solving the coupled equations in Bragg diffraction by creating MATLAB function for use in Bragg regime and acoustic-optic spatial filtering and employing mainly the MATLAB program for solving this problem. We review the role of acousto-optic and spatial filtering for high-pass spatial filtering. Classically, acousto-optic interactions comprise scattering of photons by energetic phonons into higher and lower orders. Standard weak interaction theory describes diffraction in the Bragg regime as the propagation of a uniform plane wave of light through a uniform plane wave of sound, resulting in the well known first- and zeroth-order diffraction. We investigate Raman-Nath diffraction corresponding to near-Bragg diffraction. A result shows the dependence of various scattered orders on the incident angle/Bragg angle illustrating the Bessel function dependence.

Nanoscale chiral surface relief of azo-polymers with nearfield OAM light.

An optical vortex with orbital angular momentum (OAM) can be used to induce microscale chiral structures in various materials. Such chiral structures enable the generation of a nearfield vortex, i.e. nearfield OAM light on a sub-wavelength scale, thereby leading to further nanoscale mass-transport. We report on the formation of a nanoscale chiral surface relief in azo-polymers due to nearfield OAM light. The resulting nanoscale chiral relief exhibits a diameter of ca. 400 nm, which corresponds to less than 1/5-1/6th of the original chiral structure (ca. 2.1 µm). Such a nanoscale chiral surface relief is established by the simple irradiation of uniform visible plane-wave light with an intensity of <500 mW/cm2.

Quantum features in the orthogonality of optical modes for structured and plane-wave light.

A fundamental photon creation-annihilation commutation relation underpins the familiar quantum formulation of optics. However, an internal inconsistency becomes apparent in the pursuit of structured light applications. This requires the relationship between operator commutation and mode orthogonality to be recast in a form ensuring full consistency with the precepts of quantum theory. A suitable reformulation, shown to register correctly an intrinsic quantum uncertainty in the associated interactions, has special relevance to optical vortex physics-particularly with regard to information content-through its connection to the degrees of freedom in the associated radiation modes.

Analysis of angular momentum properties of photons emitted in fundamental atomic processes

Many atomic processes result in the emission of photons. Analysis of the properties of emitted photons, such as energy and angular distribution as well as polarization, is regarded as a powerful tool for gaining more insight into the physics of corresponding processes. Another characteristic of light is the projection of its angular momentum upon propagation direction. This property has attracted a special attention over the last decades due to studies of twisted (or vortex) light beams. Measurements being sensitive to this projection may provide valuable information about the role of angular momentum in the fundamental atomic processes. Here we describe a simple theoretical method for determination of the angular momentum properties of the photons emitted in various atomic processes. This method is based on the evaluation of expectation value of the total angular momentum projection operator. To illustrate the method, we apply it to the text-book examples of plane-wave, spherical-wave, and Bessel light. Moreover, we investigate the projection of angular momentum for the photons emitted in the process of the radiative recombination with ionic targets. It is found that the recombination photons do carry a non-zero projection of the orbital angular momentum.

Can light wave behave as a beam as it is scattered by a particulate medium?

The possibility for a particulate medium to produce field which can behave as a beam is discussed. It is demonstrated that when a plane light wave is scattered from a particulate medium, the beam condition, i.e., the condition under which the scattered field could retain its beam-like form, is governed by both the property of each particle and the property of the distribution characteristic. As an example, the scattered field of a collection of Gaussian-distributed particles is discussed, and some special cases are investigated to illustrate the beam condition.

Orbital angular momentum generation via a spiral phase microsphere.

Vortex beam carrying orbital angular momentum (OAM) attracts much attention in many research fields for its special phase and intensity distributions. In this Letter, a novel design called the spiral phase microsphere (SPMS) is proposed for the first time, to the best of our knowledge, which can convert incident plane wave light into the focused vortex beam that carries OAM with different topological charges l=±1 and ±2. The vortex beam generation is verified by a self-interfered modification of the SPMS. The generation of the vortex beams by the SPMS irradiated by a single-wavelength incident light is studied using the CST MICROWAVE STUDIO simulation. The SPMS provides a new approach to achieve high-efficiency and high-integrated photonic applications related with OAM.

Effect of Substrate and Nanoparticle Spacing on Plasmonic Enhancement in Three-Dimensional Nanoparticle Structures

Surface plasmon polaritons associated with light-nanoparticle interactions can result in dramatic enhancement of electromagnetic fields near and in the gaps between the particles, which can have a large effect on the sintering of these nanoparticles. For example, the plasmonic field enhancement within nanoparticle assemblies is affected by the particle size, spacing, interlayer distance, and light source properties. Computational analysis of plasmonic effects in three-dimensional (3D) nanoparticle packings are presented herein using 532 nm plane wave light. This analysis provides insight into the particle interactions both within and between adjacent layers for multilayer nanoparticle packings. Electric field enhancements up to 400-fold for transverse magnetic (TM) or X-polarized light and 26-fold for transverse electric (TE) or Y-polarized light are observed. It is observed that the thermo-optical properties of the nanoparticle packings change nonlinearly between 0 and 10 nm gap spacing due to the strong and nonlocal near-field interaction between the particles for TM polarized light, but this relationship is linear for TE polarized light. These studies help provide a foundation for understanding micro/nanoscale heating and heat transport for Cu nanoparticle packings under 532 nm light under different polarization for the photonic sintering of nanoparticle assemblies.

Changes in the spectrum produced by scattering from a synchronous rotation system of two anisotropic particles

The scattering of a polychromatic plane light wave incident upon a synchronous rotation system of two anisotropic particles is investigated. The analytical expression for the spectrum of the scattered field is obtained. Numerical examples are given to show the phenomena of spectral shift and spectral switch of the scattered field during the synchronous rotation of the two anisotropic scatterers. The influences of the off-center parameter and the direction of scattering on the spectral changes are discussed.

Three-dimensional analysis of free-space light propagation based on quantum mechanical scattering theory of light

In this paper, a free-space light propagation analysis between 3-dimensional (3-D) volumetric spaces is proposed. In contrast to conventional scalar diffraction, the proposed theory is based on quantum mechanical scattering providing a general volumetric analysis for the free-space light propagation. Assuming a plane wave light incidence, we obtained a new analytic formula for 3-D volumetric convolution, which provided a transfer function in a closed form used for caculating the electric fields at the observation points. The proposed method was consistent with the conventional numerical methods for a 2-dimensional aperture and can be further applied to exact calculation of diffraction fields from 3-D surfaces, providing a compact reconstruction algorithm for 3-D images in a computer generated hologram.

Average intensity and scintillation of light in a turbulent biological tissue

Scintillation is one of the most important properties of light propagating through random media. The scintillation index of plane and spherical light waves as well as of a Gaussian beam propagating in the turbulent biological tissue is developed. Expressions of average intensity of Gaussian beams through turbulent tissue are also derived. Effects of the biological tissue turbulence on the average intensity and scintillation index are discussed in the numerical simulations. An analysis of the threshold between the weak and strong regimes of biological tissue turbulence is made with the variation of outer scale of turbulence. The results are of utmost importance for any applications involved light beam propagation through tissues, especially the cases where the average intensity and spreading properties of the light field should be taken into account to evaluate the system performance and investigations in the structures of biological tissue.