Polarization-dependent Interference Research Articles

Metasurface-assisted multidimensional manipulation of a light wave based on spin-decoupled complex amplitude modulation.

Achieving arbitrary manipulation of the fundamental properties of a light wave with a metasurface is highly desirable and has been extensively developed in recent years. However, common approaches are typically targeted to manipulate only one dimension of light wave (amplitude, phase, or polarization), which is not quite sufficient for the acquisition of integrated multifunctional devices. Here, we propose a strategy to design single-layer dielectric metasurfaces that can achieve multidimensional modulation of a light wave. The critical point of this strategy is spin-decoupled complex amplitude modulation, which is realized by combining propagation and geometric phases with polarization-dependent interference. As proofs of concept, perfect vector vortex beams and polarization-switchable stereoscopic holographic scenes are experimentally demonstrated to exhibit the capability of multidimensional light wave manipulation, which unlocks a flexible approach for the multidimensional manipulation of a light wave such as complex light-wave control and vectorial holography in integrated optics and polarization-oriented applications.

Dynamic generation of giant linear and circular dichroism via phase-change metasurface

Dichroism, an important property for the manipulation and characterization of polarization states, has been widely studied. However, owing to the inherent relationship between linear and circular polarization, it is difficult to generate high linear dichroism (LD) and circular dichroism (CD) in the same structure. Previous study can only solve this problem in the condition of oblique incidence. Here, a method is proposed to generate high LD and CD under normal incidence without any structural changes. By the design of metamolecule composed of two pairs of twin nanopillars, the polarization-dependent interference from those twin nanopillars can be utilized to achieve giant dichroism. Meanwhile, the phase state of Sb2S3 is introduced as an additional degree of freedom to further control the polarization-dependent interference thus generating LD and CD in the same structure. Moreover, the proposed method can achieve both LD and CD in transmission as well as reflection modes. This full-space feature was not achieved before. Due to the compactness and excellent performance, we envision that this work will advance the development of tunable dichroic devices and flat polarization optical elements in the optical integrated system.

A Simple Phase-Sensitive Surface Plasmon Resonance Sensor Based on Simultaneous Polarization Measurement Strategy.

The SPR phenomenon results in an abrupt change in the optical phase such that one can measure the phase shift of the reflected light as a sensing parameter. Moreover, many studies have demonstrated that the phase changes more acutely than the intensity, leading to a higher sensitivity to the refractive index change. However, currently, the optical phase cannot be measured directly because of its high frequency; therefore, investigators usually have to use complicated techniques for the extraction of phase information. In this study, we propose a simple and effective strategy for measuring the SPR phase shift based on phase-shift interferometry. In this system, the polarization-dependent interference signals are recorded simultaneously by a pixelated polarization camera in a single snapshot. Subsequently, the phase information can be effortlessly acquired by a phase extraction algorithm. Experimentally, the proposed phase-sensitive SPR sensor was successfully applied for the detection of small molecules of glyphosate, which is the most frequently used herbicide worldwide. Additionally, the sensor exhibited a detection limit of 15 ng/mL (0.015 ppm). Regarding its simplicity and effectiveness, we believe that our phase-sensitive SPR system presents a prospective method for acquiring phase signals.

Independent Amplitude Control of Arbitrary Orthogonal States of Polarization via Dielectric Metasurfaces.

Exquisite polarization control using optical metasurfaces has attracted considerable attention thanks to their ability to manipulate multichannel independent wavefronts with subwavelength resolution. Here we present a new class of metasurface polarization optics, which enables imposition of two arbitrary and independent amplitude profiles on any pair of orthogonal states of polarization. The implementation method involves a polarization-dependent interference mechanism achieved by constructing a metasurface composed of an array of nanoscale birefringent waveplates. Based on this principle, we experimentally demonstrate chiral grayscale metasurface and chiral shadow rendering of structured light. These results illustrate a general approach interlinking amplitude profiles and orthogonal states of polarization and expands the scope of metasurface polarization shaping optics.

Polarization-Dependent Interference of Coherent Scattering from Orthogonal Dipole Moments of a Resonantly Excited Quantum Dot.

Resonant photoluminescence excitation (RPLE) spectra of a neutral InGaAs quantum dot show unconventional line shapes that depend on the detection polarization. We characterize this phenomenon by performing polarization-dependent RPLE measurements and simulating the measured spectra with a three-level quantum model. The spectra are explained by interference between fields coherently scattered from the two fine structure split exciton states, and the measurements enable extraction of the steady-state coherence between the two exciton states.

Spectrally efficient polarization multiplexed direct-detection OFDM system without frequency gap.

We experimentally demonstrate a spectrally efficient direct-detection orthogonal frequency-division multiplexing (DD-OFDM) system. In addition to polarization-division multiplexing, removing the frequency gap further improves the spectral efficiency of the OFDM system. The frequency gap between a reference carrier and OFDM subcarriers avoids subcarrier-to-subcarrier beating interference (SSBI) in traditional DD-OFDM systems. Without dynamic polarization control, the resulting interference after square-law direct detection in the proposed gap-less system is polarization-dependent and composed of linear inter-carrier interference (ICI) and nonlinear SSBI. Thus, this work proposes an iterative multiple-input multiple-output detection scheme to remove the mixed polarization-dependent interference. Compared to the previous scheme, which only removes ICI, the proposed scheme can further eliminate SSBI to achieve the improvement of ∼ 7 dB in signal-to-noise ratio. Without the need for polarization control, we successfully utilize 7-GHz bandwidth to transmit a 39.5-Gbps polarization multiplexed OFDM signal over 100 km.

LOCAL-FIELD AND MULTIPOLAR EFFECTS IN THE SECOND-HARMONIC RESPONSE OF ARRAYS OF METAL NANOPARTICLES

The distribution details of strongly-localized fields in metal nanostructures are important for strong interaction with the locally-varying non-linearity. Using gold nanodimers with nanogaps, we demonstrate that field localization alone is insufficient to drive a strong second-order response. Instead, polarization conversion of the local fundamental field combines with its asymmetric distribution along the dimer perimeter to yield strong responses. Strongly-localized fields may also favor higher-multipole (magnetic-dipole and electric-quadrupole) contributions to their nonlinear response. We show that the polarization-dependent interference of multipole sources in second-harmonic generation from gold nanoparticles allows the separation of their relative contributions.

Polarization-dependent interference effects in grazing-angle Fourier transform infrared reflection–absorption spectroscopy to determine the thickness of water-ice films

Interference fringes appeared between 6000 and 4095 cm(-1) in the infrared spectra of thin water-ice films vapor deposited on an aluminum substrate and probed with grazing-angle Fourier transform infrared reflection-absorption spectroscopy. At grazing incidence the position of the fringe under perpendicularly polarized light (E(sigma)) is 180 degrees out of phase with the position of the fringe under parallel polarized light (E(pi)). This shift in fringe position with polarization offers a convenient way to estimate the thickness (+/-5%) of water-ice films between 0.5 and 1.4 microm.

Third- and fourth-order analysis of the intensities and polarization dependence of two-photon absorption lines ofGd3+in LaF3and aqueous solution

A comprehensive report and analysis of our observations of numerous parity-allowed direct two-photon transitions within the $4{f}^{7}$ configuration of the ${\mathrm{Gd}}^{3+}$ ion is presented. The experimental technique is ultraviolet fluorescence detection following optical excitation with a dye-laser beam. Previous results and analyses are extended in three ways. (1) The intensities and polarization dependence of individual Stark components, in addition to integrated multiplet intensities, are reported and analyzed for ${\mathrm{Gd}}^{3+}$:La${\mathrm{F}}_{3}$. In those cases ($^{8}S_{\frac{7}{2}}\ensuremath{\rightarrow}^{6}P_{\frac{5}{2}},^{6}D_{\frac{9}{2},\frac{3}{2},\frac{5}{2}}$) where a second-order theory of two-photon absorption adequately explains the integrated intensity, it also (with the exception of $^{6}D_{\frac{9}{2}}$) explains the Stark-component intensities. The remaining transitions are anomalously strong, and in some cases violate the angular momentum selection rules $\ensuremath{\Delta}L,\ensuremath{\Delta}J\ensuremath{\le}2$ and exhibit strong anisotropies, in contradiction to the second-order theory. It is shown that introduction of third- and fourth-order contributions involving spin-orbit and/or crystal-field interactions among levels of the $4{f}^{6}5d$ configuration, which serve as intermediate states, can account for both the integrated and Stark-component intensities of these transitions. (2) The strong anisotropy observed for the transitions $^{8}S_{\frac{7}{2}}\ensuremath{\rightarrow}^{6}P_{\frac{3}{2}},^{6}I_{J},^{6}D_{\frac{1}{2}}$ in ${\mathrm{Gd}}^{3+}$:La${\mathrm{F}}_{3}$ is explained quantitatively as a polarization-dependent interference between contributions to the intensity which are comparable in magnitude. Interference is destructive for $\stackrel{\ensuremath{\rightarrow}}{E}\ensuremath{\parallel}\stackrel{^}{z}$ and constructive for $\stackrel{\ensuremath{\rightarrow}}{E}\ensuremath{\perp}\stackrel{^}{z}$, creating an order-of-magnitude contrast in the line strength for the two polarizations. (3) A two-photon excitation spectrum of ${\mathrm{Gd}}^{3+}$ in aqueous solution is reported. Linewidths comparable to those of room-temperature solids and Stark splittings which suggest a low-symmetry quasistatic environment are observed.

Polarization Effects in Slow Neutron Scattering II. Spin-Orbit Scattering and Interference

The theory of polarized neutron scattering is extended to include spin-orbit scattering in magnetic substances. The cross section for scattering of a polarized beam includes, in addition to the Schwinger interference term between nuclear and spin-orbit scattering, a polarization-dependent interference term between spin-orbit and magnetic scattering. The latter depends on the real part of the product of magnetic and spin-orbit structure factors, whereas the Schwinger term depends on the imaginary part of the product of the nuclear and spin-orbit structure factors. A calculation shows that this effect should easily be observable in an isotopic mixture of Ni which has no coherent nuclear scattering.