Showing papers on "Total internal reflection published in 2018"
TL;DR: In this paper, anisotropic all-dielectric metamaterials open a new degree of freedom in total internal reflection to shorten the decay length of evanescent waves.
Abstract: Ultra-compact, densely integrated optical components manufactured on a CMOS-foundry platform are highly desirable for optical information processing and electronic-photonic co-integration. However, the large spatial extent of evanescent waves arising from nanoscale confinement, ubiquitous in silicon photonic devices, causes significant cross-talk and scattering loss. Here, we demonstrate that anisotropic all-dielectric metamaterials open a new degree of freedom in total internal reflection to shorten the decay length of evanescent waves. We experimentally show the reduction of cross-talk by greater than 30 times and the bending loss by greater than 3 times in densely integrated, ultra-compact photonic circuit blocks. Our prototype all-dielectric metamaterial-waveguide achieves a low propagation loss of approximately 3.7±1.0 dB/cm, comparable to those of silicon strip waveguides. Our approach marks a departure from interference-based confinement as in photonic crystals or slot waveguides, which utilize nanoscale field enhancement. Its ability to suppress evanescent waves without substantially increasing the propagation loss shall pave the way for all-dielectric metamaterial-based dense integration.
122 citations
TL;DR: In this paper, a reconfigurable linear-to-linear polarization conversion metasurface (Re-PCM) based on positive-intrinsic-negative (PIN) diodes is proposed, which can be reconfigured between the conversion mode and the reflection mode by switching the loaded PINs.
Abstract: A reconfigurable linear-to-linear polarization conversion metasurface (Re-PCM) based on positive-intrinsic-negative (PIN) diodes is proposed, which can be reconfigured between the conversion mode and the reflection mode by switching the loaded PIN diodes. The unit cell of the Re-PCM consists of two slotted metal square rings and bias lines, which are all etched on a substrate backed by a metal ground. In the conversion mode, the Re-PCM reflects linearly polarized incident waves with 90° polarization rotation. The simulated results show that the polarization conversion ratio is more than 88% over 3.39–5.01 GHz for x -polarized and y -polarized normally incident waves. In the reflection mode, it exhibits total reflection characteristic like a metal plate. The magnitude of co-polarization reflection is over −1 dB from 3.83 to 4.74 GHz. The physical mechanism and equivalent circuit of the Re-PCM are analyzed. To validate the simulation, a prototype of the Re-PCM is fabricated and measured. Reasonable accordance between the simulated and measured results is obtained.
84 citations
TL;DR: In this article, the first three common types of optical fibers are classified based on the structure, modes number, refractive index profile, dispersion, signal processing ability, and polarization.
Abstract: The optical fibers which are considered as waveguides can be applied to light transmission applications The core part of the optical fiber is surrounded by a glass or plastic layer called cladding which is characterized by the refractive index that is lower compared to the core refractive index The total internal reflection phenomena are necessary for the fine confinements of the light within the waveguide Basically, optical fibers can be categorized based on the structure, modes number, refractive index profile, dispersion, signal processing ability, and polarization In this report, we focus on the first three common types of optical fibers As a common application of the fibers, these can be used in fiber lasers to create and amplify a narrow intense beam of coherent and monochromatic light Fabrication of optical fiber involves three stages such as the preform formation Modified chemical vapor deposition (MCVD) method is a known technique, which can be used to fabricate the optical fibers Optical fiber sensors are well known for wide range applications in optics and photonics As a sensing application, optical biosensors can be made based on the refractive index changes that used widely for detection of biomolecules in their natural forms
78 citations
TL;DR: In this article, it was shown that a plane-wave incident at an angle greater than the angle of total internal reflection does not excite surface plasmon polaritons, however, if the incident light forms a narrow beam composed of an infinite number of plane waves.
Abstract: We consider exciting surface plasmon polaritons in the Kretschmann configuration. Contrary to common belief, we show that a plane-wave incident at an angle greater than the angle of total internal reflection does not excite surface plasmon polaritons. These excitations do arise, however, if the incident light forms a narrow beam composed of an infinite number of plane waves. The surface plasmon polariton is formed at the geometrical edge of the beam as a result of interference of reflected plane waves.
44 citations
TL;DR: In this article, it was shown that the cholesteric shells in a microfluidics produced double emulsion enable also a sequence of internal reflections if the shells have sufficiently thin top and thick bottom.
Abstract: Spheres of cholesteric liquid crystal generate dynamic patterns due to selective reflection from a helical structure subject to continuously curved boundaries. So far the patterns are investigated exclusively as function of reflections at the sphere exterior. Here it is shown that the cholesteric shells in a microfluidics produced double emulsion enable also a sequence of internal reflections if the shells have sufficiently thin top and thick bottom. While such asymmetry is promoted by buoyancy when the internal droplet has lower density than the liquid crystal, the elasticity of the cholesteric helix prefers a symmetric shell geometry, acting against gravity. This subtle balance can hide the internal reflections for long time. Eventually, however, the asymmetry is established, revealing a new class of photonic patterns characterized by colored sharp concentric rings. With the complete knowledge of the diverse light-reflecting behavior of cholesteric liquid crystal shells, and utilizing the tunability of the structure period by, e.g., temperature, electric field, or exposure to various chemical species as well as polymer stabilization for making the shells long-term stable, they may be developed into remarkable new optical elements for photonics, sensing, or security pattern generation.
41 citations
TL;DR: The Total Internal Reflection metasurface (TIR-MS) as mentioned in this paper was proposed to achieve vibration isolation and energy filtering in certain prototypical structures of interest for practical engineering applications.
Abstract: This letter presents the concept of the Total Internal Reflection metasurface (TIR-MS) which supports the realization of structure-embedded subwavelength acoustic shields for elastic waves propagating in thin waveguides. The proposed metasurface design exploits extreme phase gradients, implemented via locally resonant elements, in order to achieve operating conditions that are largely beyond the critical angle. Such artificial discontinuity is capable of producing complete reflection of the incoming waves regardless of the specific angle of incidence. From a practical perspective, the TIR-MS behaves as a sound hard barrier that is impenetrable to long-wavelength modes at a selected frequency. The TIR metasurface concept is first conceived for a flat interface embedded in a rectangular waveguide and designed to block longitudinal S0-type guided modes. Then, it is extended to circular plates in order to show how enclosed areas can be effectively shielded by incoming waves. Given the same underlying physics, an equivalent dynamic behavior was also numerically and experimentally illustrated for flexural A0-type guided modes. This study shows numerical and experimental evidence that, when the metasurface is excited at the target frequency, significant vibration isolation can be achieved in the presence of waves having any arbitrary angle of incidence. These results open interesting paths to achieve vibration isolation and energy filtering in certain prototypical structures of interest for practical engineering applications.
40 citations
TL;DR: The procedure to excite a plasmon wave in gaseous media and perform refractive index measurements in these environments are described and developed platforms exhibit a temperature insensitive response of 78 nm/RIU when tested with different gases.
Abstract: Surface plasmon resonance excitation with optical fiber gratings has been typically studied in aqueous solutions. This work describes the procedure to excite a plasmon wave in gaseous media and perform refractive index measurements in these environments. Grating photo-inscription with 193 nm excimer laser radiation allows us to obtain slightly tilted fiber Bragg gratings exhibiting a cladding mode resonance comb along several hundreds of nanometers. Their refractive index sensitive range extends from gases to liquids, so operation in both media is compared. We demonstrate that the thickness of the metal coating required for surface plasmon excitation in gases is roughly one third of the one usually used for liquids. The developed platforms exhibit a temperature insensitive response of 78 nm/RIU when tested with different gases.
39 citations
TL;DR: The Total Internal Reflection metasurface (TIR-MS) as mentioned in this paper was proposed to achieve vibration isolation and energy filtering in certain prototypical structures of interest for practical engineering applications.
Abstract: This letter presents the concept of Total Internal Reflection metasurface (TIR-MS) which supports the realization of structure-embedded subwavelength acoustic shields for elastic waves propagating in thin waveguides. The proposed metasurface design exploits extreme phase gradients, implemented via locally resonant elements, in order to achieve operating conditions that are largely beyond the critical angle. Such artificial discontinuity is capable of producing complete reflection of the incoming waves regardless of the specific angle of incidence. From a practical perspective, the TIR-MS behaves as a sound hard barrier that is impenetrable to long-wavelength modes at a selected frequency. The TIR metasurface concept is first conceived for a flat interface embedded in a rectangular waveguide and designed to block longitudinal S0-type guided modes. Then, it is extended to circular plates in order to show how enclosed areas can be effectively shielded by incoming waves. Given the same underlying physics, an equivalent dynamic behavior was also numerically and experimentally illustrated for flexural A0-type guided modes. This study shows numerical and experimental evidence that, when the metasurface is excited at the target frequency, significant vibration isolation can be achieved in presence of waves having any arbitrary angle of incidence. These results open interesting paths to achieve vibration isolation and energy filtering in certain prototypical structures of interest for practical engineering applications.
38 citations
TL;DR: In this article, the performance of labyrinthine acoustic metamaterials with internal channels folded along a Wunderlich space-filling curve to control low-frequency sound in air is analyzed.
Abstract: We numerically analyze the performance of labyrinthine acoustic metamaterials with internal channels folded along a Wunderlich space-filling curve to control low-frequency sound in air. In contrast to previous studies, we perform direct modeling of wave propagation through folded channels, not introducing effective theory assumptions. As a result, we reveal that metastructures with channels, which allow wave propagation in the opposite direction to incident waves, have different dynamics as compared to those for straight slits of equivalent length. The differences are attributed to activated tortuosity effects and result in 100% wave reflection at band gap frequencies. This total reflection phenomenon is found to be insensitive to thermo-viscous dissipation in air. For labyrinthine channels generated by iteration levels, one can achieve broadband total sound reflection by using a metamaterial monolayer and efficiently control the amount of absorbed wave energy by tuning the channel width. Thus, the work contributes to a better understanding of labyrinthine metamaterials with potential applications for reflection and filtering of low-frequency airborne sound.
36 citations
TL;DR: In this article, a generalized waveguide condition is derived analytically based on the coherent perfect reflection, and the modes that satisfy this condition are precisely bound states in the continuum.
Abstract: A mechanism for perfect reflection is proposed for the dielectric medium beyond the total internal reflection and band gaps. It arises from the coherence of multiple propagating modes, and can be determined by the topological vortex of a transmission coefficient with a nonzero winding number in parameter space. Based on the coherent perfect reflection, a generalized waveguide condition is derived analytically. In a photonic crystal slab, the modes that satisfy this condition are precisely bound states in the continuum. Our findings may have many potential applications in guided-wave optics.
35 citations
TL;DR: An angle measurement system using orthogonal mirror self-mixing interferometry combine an orthogona mirror with designed mechanical linkage overcomes the shortcomings of traditional angle measurement methods and realized the angle measurement with microradian resolution in a full-circle range of 0 rad to 2π rad.
Abstract: The self-mixing technique based on the traditional reflecting mirror has been demonstrated with great merit for angle sensing applications. In order to solve the problems of the narrow measurement angle range and low resolution in traditional angle measurement method, we proposed an angle measurement system using orthogonal mirror self-mixing interferometry combine an orthogonal mirror with designed mechanical linkage. It overcomes the shortcomings of traditional angle measurement methods and realized the angle measurement with microradian resolution in a full-circle range of 0 rad to 2π rad. In the experiment, the measurement resolution can reach to 5.27 µrad and the absolute error can lower to ± 0.011µrad, which satisfies the requirements of most high accuracy angle measurement.
TL;DR: In this paper, two kinds of black silicon models were studied via the finite differences time domain method, and the simulated reflectance spectra matched well with the measured curve and the light intensity distribution within the nanostructures showed that near 80% of the incident light are redirected and subjected to internal reflection.
Abstract: There is a wide application prospect in black silicon, especially in solar cells and photoelectric detectors. For further optimization of black silicon, it is important to study its optical properties. Especially, the influence of the surface nanostructures on these properties and the light propagation within the nanostructures are relevant. In this paper, two kinds of black silicon models are studied via the finite differences time domain method. The simulated reflectance spectra matches well with the measured curve. Also, the light intensity distribution within the nanostructures shows that near 80% of the incident light are redirected and subjected to internal reflection, which provides powerful support for the good light trapping properties of black silicon.
TL;DR: In this article, the resonant optical tunneling effect (ROTE) was used to enhance the spin Hall effect (SHE) of transmitted light, and a maximum transverse shift of the horizontal polarization state in the ROTE structure of about 22.25 µm has been obtained, which is at least three orders of magnitude greater than the transverse shifts in the frustrated total internal reflection structure.
Abstract: Due to the quantum analogy with optics, the resonant optical tunneling effect (ROTE) has been proposed to investigate both the fundamental physics and the practical applications of optical switches and liquid refractive index sensors. In this paper, the ROTE is used to enhance the spin Hall effect (SHE) of transmitted light. It is demonstrated that sandwiching a layer of a high-refractive-index medium (boron nitride crystal) between two low-refractive-index layers (silica) can effectively enhance the photonic SHE due to the increased refractive index gradient and an enhanced evanescent field near the interface between silica and boron nitride. A maximum transverse shift of the horizontal polarization state in the ROTE structure of about 22.25 µm has been obtained, which is at least three orders of magnitude greater than the transverse shift in the frustrated total internal reflection structure. Moreover, the SHE can be manipulated by controlling the component materials and the thickness of the ROTE structure. These findings open the possibility for future applications of photonic SHE in precision metrology and spin-based photonics.
09 Feb 2018
TL;DR: In this paper, the authors combined a VO2-based grating structure with a total internal reflection geometry providing a novel interaction mechanism between the electromagnetic waves and the device, to realize a powerful active broadband THz polarization-controlling device.
Abstract: Active broadband terahertz (THz) polarization manipulation devices are challenging to realize, but also of great demand in broadband terahertz systems. Vanadium dioxide (VO2) shows a promising phase transition for active control of THz waves and provides broadband polarization characteristics when integrated within grating-type structures. We creatively combine a VO2-based grating structure with a total internal reflection (TIR) geometry providing a novel interaction mechanism between the electromagnetic waves and the device, to realize a powerful active broadband THz polarization-controlling device. The device is based on a Si-substrate coated with a VO2 layer and a metal grating structure on top, attached to a prism for generating the TIR condition on the Si-VO2-grating interface. The grating is connected to electrodes for electrically switching the VO2 between its insulating and conducting phases. By properly selecting the incident angle of the THz waves, the grating direction, and the incident polariz...
TL;DR: This paper introduces a series of weak measurement working areas by adjusting the pre-selection and post-selection states and the total phase difference between vertically polarized light and horizontally polarized light, and the measurement of the weak value is amplified by several times in one system.
Abstract: Phase-sensitive weak measurement systems have been receiving an increasing amount of attention. In this paper, we introduce a series of weak measurement working areas. By adjusting the pre-selection and post-selection states and the total phase difference between vertically polarized light and horizontally polarized light, the measurement of the weak value is amplified by several times in one system. Its applicability is verified in a label-free total internal reflection system. The original sensitivity and resolution are improved at different working areas, reaching 1.85 um/refractive index unit (RIU) and 6.808 × 10-7 RIU, respectively.
TL;DR: In this paper, a metallic wire grating loaded with graphene and operating in total internal reflection (TIR) geometry was employed to realize deep and broadband THz modulation, achieving a ∼77% modulation depth in the frequency range of 0.2 − 1.4
Abstract: We employed a metallic wire grating loaded with graphene and operating in total internal reflection (TIR) geometry to realize deep and broadband THz modulation. The non-resonant field enhancement effect of the evanescent wave in TIR geometry and in the subwavelength wire grating was combined to demonstrate a ∼77% modulation depth (MD) in the frequency range of 0.2–1.4 THz. This MD, achieved electrically with a SiO2/Si gated graphene device, was 4.5 times higher than that of the device without a metal grating in transmission geometry. By optimizing the parameters of the metallic wire grating, the required sheet conductivity of graphene for deep modulation was lowered to 0.87 mS. This work has potential applications in THz communication and real-time THz imaging.
TL;DR: In this paper, it was shown that in the transition regime, lowfrequency oscillations (the interference structure) of SSA as function of size parameter occur for relatively small imaginary parts of the refractive index and are caused by interference between transmitted and diffracted components of the scattered light.
Abstract: Aerosol single scattering albedo (SSA) is the most important intensive particle parameter controlling aerosol direct radiative forcing. For homogeneous, spherical particles and a complex refractive index independent of wavelength, the SSA is solely dependent on size parameter (ratio of particle circumference and wavelength) and complex refractive index of the particle and can be accurately calculated with Mie theory. Here, we explore this dependency for particles of intermediate size in the transition or peak regime between the Rayleigh scattering and geometric optics regimes. We show that in the transition regime, low-frequency oscillations (the interference structure) of SSA as function of size parameter occur for relatively small imaginary parts of the refractive index and are caused by interference between transmitted and diffracted components of the scattered light. Anomalous diffraction theory (ADT) semi-quantitatively describes this behavior of the SSA as function of size parameter and complex refractive index. While ADT accurately gives the size parameters of the interference peaks, ADT amplitudes only approximate exact Mie results. A significant improvement in agreement with Mie theory can be obtained with modified ADT (MADT) that adds a parameterization for the physics neglected in ADT, namely internal reflection/refraction, photon tunneling, and edge diffraction.
TL;DR: The prototype offers more flexibility of pattern period and illumination orientation changing than previous systems, and a twofold resolution improvement is achieved in the experiments.
Abstract: We present an alternative approach to realize structured illumination microscopy (SIM), which is capable for live cell imaging. The prototype utilizes two sets of scanning galvo mirrors, a polarization converter and a piezo-platform to generate a fast shifted, s-polarization interfered and periodic variable illumination patterns. By changing the angle of the scanning galvanometer, we can change the position of the spots at the pupil plane of the objective lens arbitrarily, making it easy to switch between widefield and total internal reflection fluorescent-SIM mode and adapting the penetration depth in the sample. Also, a twofold resolution improvement is achieved in our experiments. The prototype offers more flexibility of pattern period and illumination orientation changing than previous systems.
TL;DR: In this article, a detailed theoretical study of the Goos-Hanchen (GH) shift for a fundamental Gaussian beam on the surface coated with monolayer (ML) molybdenum disulfide (MoS2), a promising two-dimensional transition metal dichalcogenide (2D-TMDC) and a direct band-gap semiconductor, is presented.
Abstract: We report a detailed theoretical study of the Goos–Hanchen (GH) shift for a fundamental Gaussian beam on the surface coated with monolayer (ML) molybdenum disulfide (MoS2), a promising two-dimensional transition metal dichalcogenide (2D-TMDC) and a direct band-gap semiconductor. A general model has been developed to predict the GH shifts on ML-MoS2-coated surfaces for a light beam with different wavelengths. In contrast to the conventional GH shift, which is generally observed for total internal reflection, here we predict finite spatial and angular GH shift for both partial and total internal reflection conditions. Our analysis revealed that the observation of the giant negative spatial GH shift on MoS2-coated surfaces is attributed to the surface conductivity of the MoS2 ML, something that has never been explored. Furthermore, we find that the GH shifts are dependent on the mode of polarization, the wavelength of incident beam, and the nature of surfaces. This deepens our understanding of the unusual behavior of GH shift near Brewster’s angle as well as the critical angle of incidence. We expect that our findings will lead to several new applications of MoS2 in sensors and device technology.
TL;DR: A calibration slide is developed to directly characterize the TIRF excitation field and confirms the theoretically predicted exponential decay over increasing step heights as well as the presence of a non-evanescent contribution.
Abstract: Total internal reflection fluorescence (TIRF) microscopy is a commonly used method for studying fluorescently labeled molecules in close proximity to a surface. Usually, the TIRF axial excitation profile is assumed to be single-exponential with a characteristic penetration depth, governed by the incident angle of the excitation laser beam towards the optical axis. However, in practice, the excitation profile does not only comprise the theoretically predicted single-exponential evanescent field, but also an additional non-evanescent contribution, supposedly caused by scattering within the optical path or optical aberrations. We developed a calibration slide to directly characterize the TIRF excitation field. Our slide features ten height steps ranging from 25 to 550 nanometers, fabricated from a polymer with a refractive index matching that of water. Fluorophores in aqueous solution above the polymer step layers sample the excitation profile at different heights. The obtained excitation profiles confirm the theoretically predicted exponential decay over increasing step heights as well as the presence of a non-evanescent contribution.
TL;DR: In this paper, the authors investigated theoretically the photonic spin Hall effect (SHE) in a layered nanostructure containing graphene, and showed that the reflected and transmitted beams can both be enhanced near the tunneling resonance through manipulating the voltage applied to graphene via an exterior gate.
Abstract: We investigate theoretically the photonic spin Hall effect (SHE) in a layered nanostructure containing graphene When a propagating wave exists in a nanostructure containing graphene, it is found that near the transmission resonance of the nanostructure, the giant photonic SHE of the reflected beam is present When an evanescent wave exists in a nanostructure containing graphene, we show that the photonic SHE of the reflected and transmitted beams can both be enhanced near the tunneling resonance Through manipulating the voltage applied to graphene via an exterior gate, the corresponding large transverse displacement of the light beam from the photonic SHE near resonance can be easily regulated By combing with the weak measurement method, it is expected that these phenomena may lead to some potential application for developing new nanophotonic devices
TL;DR: In this article, a nanoscale plasmonic enhanced Electromagnetic Induced Transparency (EIT) and Velocity Selective Optical Pumping (VSOP) effects in miniaturized Integrated Quantum Plasmoner Device (IQPD) for D2 transitions in rubidium (Rb) were observed.
Abstract: In this work, we experimentally observe for the first time nanoscale plasmonic enhanced Electromagnetically Induced Transparency (EIT) and Velocity Selective Optical Pumping (VSOP) effects in miniaturized Integrated Quantum Plasmonic Device (IQPD) for D2 transitions in rubidium (Rb). Our device consists of a vapor cell integrated on top of a prism coated with a thin layer of metal. This configuration is known to allow efficient excitation of Surface Plasmon Resonance (SPR). The evanescent field of the surface plasmon mode interacts with the atomic media in close vicinity to the metal. In spite of the limited interaction length between SPR and Rb atoms, the signature of EIT along with VSOP signals could be clearly observed in our miniaturized IQPD under proper conditions of pump and probe intensities. A gradual decrease in the contrast of the plasmonic enhanced EIT and VSOP signals was observed as the excitation was detuned from the SPR critical angle, due to reduction in electromagnetic field enhancement,...
TL;DR: In this paper, the unusual scattering properties reported recently for structures alternating dielectric layers of subwavelength thicknesses near the critical angle for total reflection were inspected, and it was shown that the propagation is simply dispersive with local dispersion while the boundary layer effects are captured through a nonintuitive transmission condition.
Abstract: We inspect the unusual scattering properties reported recently for structures alternating dielectric layers of subwavelength thicknesses near the critical angle for total reflection. In TE polarization, the unusual scattering properties are captured by an effective model with an accuracy less than 1% up to $kd\ensuremath{\sim}0.1$. It is shown that the propagation is simply dispersive with local dispersion while the boundary layer effects are captured through a nonintuitive transmission condition. The resulting model involves two parameters depending only on the characteristics of the multilayer and which are given in closed forms. Besides, we show that a discrete description of the spectrum using the layer thickness $d$ as unit of measure misses the complexity of the continuous spectrum exhibiting strong variations within the scale $d$. This ultrasensitivity to variations below $d$ is attributable to strong boundary layer effects and, for large structures, to a cooperation between the boundaries and the phase accumulation within the structure.
TL;DR: In this paper, the effect of substrate material selection for multilayer diffractive optical elements (MLDOEs) on polychromatic integral diffraction efficiency (PIDE) was studied in the oblique incident situation.
TL;DR: In this article, total reflection X-ray photoelectron spectroscopy (TRXPS) is applied in the analysis of Ti and TiO2 nanolayers deposited on silicon and silicon dioxide substrates.
TL;DR: Reflective-mode lensless imaging of a patterned multi-layer mask sample at extreme ultraviolet wavelength that provides a finely structured defect map of the sample under test is reported on.
Abstract: While the industrial implementation of extreme ultraviolet lithography for upcoming technology nodes is becoming ever more realistic, a number of challenges have yet to be overcome. Among them is the need for actinic mask inspection. We report on reflective-mode lensless imaging of a patterned multi-layer mask sample at extreme ultraviolet wavelength that provides a finely structured defect map of the sample under test. Here, we present the imaging results obtained using ptychography in reflection mode at 6° angle of incidence from the surface normal and 13.5 nm wavelength. Moreover, an extended version of the difference map algorithm is employed that substantially enhances the reconstruction quality by taking into account both long and short-term variations of the incident illumination.
TL;DR: In this article, the authors presented an alternative view of XPM in which the pump pulse creates a moving refractive-index boundary that splits the probe pulse into two parts with distinct optical spectra through temporal reflection and refraction inside a dispersive nonlinear medium.
Abstract: Cross-phase modulation (XPM) is commonly viewed as a nonlinear process that chirps a probe pulse and modifies its spectrum when an intense pump pulse overlaps with it Here we present an alternative view of XPM in which the pump pulse creates a moving refractive-index boundary that splits the probe pulse into two parts with distinct optical spectra through temporal reflection and refraction inside a dispersive nonlinear medium The probe even undergoes a temporal version of total internal reflection for sufficiently intense pump pulses, a phenomenon that can be exploited for making temporal waveguides We investigate the practical conditions under which XPM can be exploited for temporal reflection and waveguiding The width and shape of the pump pulses as well as the nature of the medium dispersion at the pump and probe wavelengths (normal versus anomalous) play important roles The super-Gaussian shape of a pump pulse is particularly helpful because of the relatively sharp edges of the super-Gaussian shape When the pump wavelength lies in the anomalous-dispersion regime, the pump pulse can form a soliton, whose unique properties can be exploited to our advantage We also discuss a potential application of XPM-induced temporal waveguides for compensating for timing jitter
TL;DR: In this paper, a new mode of liquid crystal alignment based on photo alignment AtA-2 azo dye where the refractive interface between orthogonal orientations of the LC director exists without voltage and disappeared or changed with critical voltage has been proposed.
TL;DR: By means of time-resolved scanning Kerr microscopy, this work is able to directly detect a phase shift between the incoming and reflected wave and shows that this phase shift naturally occurs for spin waves in the dipolar regime.
Abstract: In optics, a light beam experiences a spatial shift in the beam plane upon total internal reflection. This shift is usually referred to as the Goos-Hanchen shift. When dealing with plane waves, it manifests itself as a phase shift between an incoming and reflected wave that depends on the wave vector component along the interface. In the experiments presented here, plane spin waves are excited in a 60-nm-thick Permalloy film and propagate towards the edge of the film. By means of time-resolved scanning Kerr microscopy, we are able to directly detect a phase shift between the incoming and reflected wave. With the help of a numerical model, we show that this phase shift naturally occurs for spin waves in the dipolar regime.
TL;DR: The giant modulation of visible light scattering from achiral gold half-rings when switching between evanescent surface wave excitation produced from the total internal reflection of left-handed and right-handed circularly polarized light is reported.
Abstract: For applications seeking to realize on-chip polarization-discriminating nanoantennas, efficient energy conversion from surface waves to far-field radiation is desirable. However, the response of individual nanoantennas to the particular polarization states achievable in surface waves, such as evanescent fields, has not yet been thoroughly investigated. Here, we report the giant modulation of visible light scattering from achiral gold half-rings when switching between evanescent surface wave excitation produced from the total internal reflection of left-handed and right-handed circularly polarized light. The effect is driven by a differing relative phase between the in-plane transverse and longitudinal field oscillations of the evanescent wave depending on the incident light handedness. Because longitudinal field oscillations are not found in free-space excitation, this presents a fundamentally different mechanism for chiroptical responses as traditional mechanisms for circular dichroism only account for p...