Multiple Bragg Diffraction Research Articles

Exploring the labyrinth of light: multiple Bragg Diffraction phenomena in face-centered cubic photonic crystals

This work presents the outcomes of an experimental study aimed at exploring electron diffraction phenomena within a controlled environment. The experiment involved measuring the radii of diffraction rings produced under varying acceleration voltages, with a focus on the first-order ring. Unexpectedly, the observed values were half of the anticipated results, raising questions about the accuracy of the measurements. The analysis revealed that the measured value of d1 closely resembled the theoretical value of d2, suggesting a potential oversight of the first diffraction ring, possibly due to its diminutive size. The high brightness of the incident light further complicated the measurement process. Accounting for the possibility of overlooking the first diffraction ring, the derived values for d2 (128.24±33.26 pm) and d3 (70.00±5.21 pm) were compared to theoretical values (123 pm and 80 pm, respectively). Despite the challenges, the experimental results fell within an acceptable range, considering the inherent uncertainties. To mitigate errors in radii measurement, the article suggests the implementation of an automated system and recommends a thorough reassessment of experimental setup configurations to optimize conditions for more accurate measurements. The findings highlight the importance of methodological refinement to enhance precision and reliability in electron diffraction studies. This work contributes valuable insights to the field and underscores the continuous need for advancements in experimental techniques.

Acoustic response of a laser-excited polycrystalline Au-film studied by ultrafast Debye–Scherrer diffraction at a table-top short-pulse x-ray source

The transient acoustic response of a free-standing, polycrystalline thin Au-film upon femtosecond optical excitation has been studied by time-resolved Debye–Scherrer x-ray diffraction using ultrashort Cu Kα x-ray pulses from a laser-driven plasma x-ray source. The temporal strain evolution has been determined from the transient shifts of multiple Bragg diffraction peaks. The experimental data are in good agreement with the results of calculations based on the two-temperature model and an acoustic model assuming uniaxial strain propagation in the laser-excited thin film.

Polarization-dependent multiple Bragg diffraction in the high-energy region of three-dimensional photonic crystals

We have studied angle- and polarization-dependent multiple Bragg diffraction in the high-energy region of a three-dimensional photonic crystal, which is quite distinctive as compared to the low-energy region. We identify polarization-dependent prominent multiple Bragg diffraction at different angular ranges. The decrease and increase in the peak reflectivity of diffraction peaks confirm the energy exchange between them in the coupling region. The TE-polarized light interacts strongly with crystal compared to TM polarization in the high-energy region, which agrees with theory. The results are useful for designing devices with the selective tuning of Bragg diffracted wavelengths in a broad wavelength range for applications like optical switches, waveguides, and filters.

Optical Anisotropy of Photonic Crystals of Cubic Symmetry Induced by Multiple Diffraction of Light

The optical spectra of Bragg reflection from opal-like photonic crystals under conditions of the resonant enhancement of the multiple diffraction of light have been studied experimentally and theoretically using the photonic crystal structures prepared of monodisperse polystyrene globules. It is shown that the reflection signal registered in mutually orthogonal configurations of the polarizer and analyzer is related to the intrinsic optical anisotropy of the crystals and is a specific manifestation of the multiple Bragg diffraction in three-dimensional photonic crystals.

Multiple nonlinear Bragg diffraction of femtosecond laser pulses in a photonic lattice with hexagonal domains

The frequency doubling of femtosecond laser pulses in a two-dimensional (2D) rectangular nonlinear photonic lattice with hexagonal domains is studied experimentally and theoretically. The broad fundamental spectrum enables frequency conversion under nonlinear Bragg diffraction for a series of transverse orders at a fixed longitudinal quasi-phase-matching order. The consistent nonstationary theory of the frequency doubling of femtosecond laser pulses is developed using the representation based on the reciprocal lattice of the structure. The calculated spatial distribution of the second-harmonic spectral intensity agrees well with the experimental data. The condition for multiple nonlinear Bragg diffraction in a 2D nonlinear photonic lattice is offered. The hexagonal shape of the domains contributes to multibeam second harmonic excitation. The maximum conversion efficiency for a series of transverse orders in the range 0.01%–0.03% is obtained.

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AbstractThe optical spectra of Bragg reflection from opal-like photonic crystals under conditions of the resonant enhancement of the multiple diffraction of light have been studied experimentally and theoretically using the photonic crystal structures prepared of monodisperse polystyrene globules. It is shown that the reflection signal registered in mutually orthogonal configurations of the polarizer and analyzer is related to the intrinsic optical anisotropy of the crystals and is a specific manifestation of the multiple Bragg diffraction in three-dimensional photonic crystals.

Optical anisotropy of cubic photonic crystals under conditions of multiple-mode light propagation

Bragg reflection spectra of light are studied for opal-like photonic crystals made of polystyrene spheres. A resonant enhancement of reflectivity is observed in cross-polarization configuration of the analyzer and polarizer when varying the azimuthal orientation of a sample in respect to the incidence plane. The cross-polarization effect takes place at oblique incidence of light on the lateral (111) crystal plane with the plane of incidence being non-perpendicular to the inclined (11-1) crystal plane. The effect is shown to be due to the multiple Bragg diffraction of light when the resonant Bragg conditions are fulfilled at a certain angle of incidence and azimuth for the lateral and inclined crystal planes simultaneously.

Multiple Bragg diffraction at W point in the face centered cubic photonic crystals

We report the experimental observation of multiple Bragg diffraction that occurs when the tip of the incident wave vector lies on a line joining the L and W points in the Brillouin zone of a face-centered cubic (FCC) photonic crystal. The multiple Bragg diffraction is analyzed for photonic crystals with different lattice constants and refractive index contrasts. Angle-dependent reflectance spectroscopy indicates strong hybridization of diffraction resonances when the tip of the incident wave vector crosses the W point and the multiple Bragg diffraction is seen to be extended over an angular range of 8 deg around the W point. We also observe a new diffraction resonance in the short-wavelength region for wave vectors shifting toward the W point in the hexagonal facet of the FCC Brillouin zone. Each diffraction resonance is fitted using the Bragg’s law for different planes in the FCC photonic crystal taking into account the internal angle between the planes. The diffraction resonances in the multiple Bragg diffraction regime are assigned to FCC crystal planes with Miller indices (111), (200), (1¯11), and (220). Our results have implications for diverse kinds of wave propagations in periodic structures and applications in light emission, sensing, and structural color pigments.

Multiple Bragg diffraction in opal-based photonic crystals: Spectral and spatial dispersion

We present an experimental and theoretical study of multiple Bragg diffraction from synthetic opals. An original setup permits us to overcome the problem of the total internal light reflection in an opal film and to investigate the diffraction from both the $(111)$ and $(\overline{1}11)$ systems of planes responsible for the effect. As a result, angle- and frequency-resolved diffraction and transmission measurements create a picture of multiple Bragg diffraction that includes general agreement between dips in the transmission spectra and diffraction peaks for each incident white light angle and a twin-peak structure at frequencies of the photonic stop band edges. Two opposite cases of the interference are discussed: an interference of two narrow Bragg bands that leads to multiple Bragg diffraction with anticrossing regime for dispersion photonic branches and an interference of a narrow Bragg band and broad disorder-induced Mie background that results in a Fano resonance. A good quantitative agreement between the experimental data and calculated photonic band structure has been obtained.

Influence of the multiple Bragg diffraction on the light reflection spectra of inverted Opal-GaN nanocomposites

The Bragg light reflection spectra of inverted opal-GaN composite registered at a fixed angle of light incidence on the growth surface of a sample, but different azimuth positions relative to incident radiation are presented. Significant influence of the azimuth sample orientation on the shape of the reflection spectra caused by multiple Bragg diffraction of light is demonstrated. To explain the observed effects, the mechanism of the double Bragg diffraction of light on the system of {111} and {200} planes of the FCC lattice of the sample is proposed.

Superprism phenomenon in two-dimensional magnetophotonic crystals: Experiment and numerical simulation

Magneto-optical phenomena in quasi two-dimensional magnetophotonic crystals (Q-2D MPCs) have been investigated experimentally and numerically. Multiple Bragg diffraction was shown to be responsible for enhancement of the Faraday rotation and for alteration of its sign in spectra of experimental samples fabricated from bismuth-substituted yttrium iron garnet. It was shown that, for the magnetic superprism effect–control of the light propagation direction by the external magnetic, materials with much larger magneto-optical activity than that of experimental samples are necessary. Spectra obtained by numerical simulations were in a good agreement with experimental ones. Magnetic superprism effect was demonstrated for model samples and parameters necessary for alteration flow of light in quasi-2D MPCs were obtained.

Multiple Bragg diffraction in low-contrast photonic crystals based on synthetic opals

The phenomenon of multiple Bragg diffraction in low-contrast photonic crystals based on synthetic opals has been studied both experimentally and theoretically. The transmission and reflection spectra of opal films near the K point of the Brillouin zone of the face-centered cubic lattice in s-polarization exhibit the effect of anticrossing of dispersion curves corresponding to the (111) and \((\bar 111)\) photonic stop bands. The effect of quasi-Brewster suppression of stop bands is clearly pronounced in p-polarization. The experimental data are analyzed using the calculation of the band structure of opal with the inclusion of the polarization of incident light.

Interference of additional modes in spectra of opal-like photonic crystals in the multiple diffraction regime

The mechanisms of formation of Bragg reflectance and transmittance spectra have been investigated for films of three-dimensional opal-like photonic crystals. Attention has been drawn to the fact that the spectra exhibit an additional short-period interference structure of the novel type due to the multiple Bragg diffraction of light. The spectra have been calculated in the framework of the dynamical three-wave diffraction model taking into account strong spatial modulation of the dielectric function. It has been found that short-period oscillations appear in the spectra due to the spatial quantization of additional modes with a low group velocity.

Resonant multiple diffraction of light in 3D opal‐like photonic crystals

AbstractPropagation of electromagnetic waves in spatially confined three‐dimensional (3D) photonic crystals (PhCs) of high dielectric contrast is studied for the case when the regime of the multiple Bragg diffraction (MBD) is of importance. The Bragg reflection spectra of opal‐like PhCs made up of polystyrene spheres are measured. Detailed comparison of the eigenmode energy spectrum with the measured and calculated reflectance contours is performed. The complicated structure of the Bragg reflection spectra is shown to be due to the additional eigenmodes excited resonantly by diffraction of light from the crystal planes inclined to the lateral ones.

Multiple diffraction in two-dimensional magnetophotonic crystals fabricated by the autocloning method

Quasi-2D magnetophotonic crystals (MPCs) comprising bismuth-substituted yttrium iron garnet/silicon dioxide multilayers were fabricated on top of 1D structured substrates and evaluated. Optical and magneto-optical (MO) spectra showed that light coupling to the structure of these MPCs happened in multiple Bragg diffraction regimes, where a mixing of modes with resonant wavelengths occurred within MPCs and a demultiplexing phenomenon was observed. Responses from the crystals were studied in transmission and diffraction geometries. We show that nano-scale tailoring of MPCs’ structure allows one to increase significantly the MO efficiency of magnetic materials and invert their natural MO responses.

Multiple Bragg diffraction in magnetophotonic crystals

We demonstrate properties of magnetophotonic crystals (MPCs) with quasi-two-dimensional structure. Crystals were bismuth-substituted yttrium iron garnet/silicon dioxide (Bi:YIG/SiO2) multilayers sputtered on top of one-dimensional structured substrates. Parameters of these MPCs were such that two spectrally neighboring stop bands overlapped in their spectra. For MPCs in this multiple Bragg diffraction regime, we observed a strong dispersion of their magneto-optical responses—an enhancement of the polarization rotation and an alteration of the rotation sign.

Multiple Bragg diffraction in polymeric photonic crystals

A systematic study of the angle-resolved photonic stop band of three-dimensionally (3D) ordered polymeric photonic crystals fabricated using a colloidal self-assembling method is presented. The first-order photonic stop band shows a single peak in reflection and shifts toward shorter wavelengths for larger angles of incidence. Beyond an angle of incidence of 45 degrees , a new peak arises in the reflection spectrum due to the coupling of the incident light into other directions of the fcc Brillouin zone. The predominant contribution is identified as being due to reflection from the (200) plane.

Diffraction processes in 3D photonic crystals based on thin opal films

Coupling of polarized light to thin opal films was examined to characterize their crystalline structure and diffraction processes in them. Photonic stop bands were observed in transmission (reflection) spectra and attributed to diffraction from the {111} crystallographic planes of the twinned fcc structure. Weakening and collapses of stop bands for linearly polarized light demonstrated a strong anisotropy of light propagation in the films. Reflection spectra of the films under the s-polarized light illumination highlighted an unusual behavior of light scattering. Multiple Bragg diffraction accompanied by leakage and inflow of energy to major diffraction lobes has been detected and described in detail.

Polarized light coupling to thin silica-air opal films grown by vertical deposition

Coupling of polarized light to thin silica-air opal films---representatives of high contrast three-dimensional photonic crystals---has been studied in detail. Photonic stop bands were observed in transmission (reflection) spectra and attributed to diffraction from the {111} crystallographic planes of the twinned fcc structure. Polarization-resolved transmission spectra manifest a strong anisotropy of light propagation in the films---collapses of stop bands have been demonstrated for the $p$-polarized light. Reflection spectra of the films under the $s$-polarized light illumination highlight an unusual behavior of light scattering. Scattered intensity was found to be influenced by multiple Bragg diffraction accompanied by leakage and inflow of energy to major diffraction lobes.

Slow to superluminal light waves in thin 3D photonic crystals

Phase measurements on self-assembled three-dimensional photonic crystals show that the group velocity of light can flip from small positive (slow) to negative (superluminal) values in samples of a few mum size. This phenomenon takes place in a narrow spectral range around the second-order stop band and follows from coupling to weakly dispersive photonic bands associated with multiple Bragg diffraction. The observations are well accounted for by theoretical calculations of the phase delay and of photonic states in the finite-sized systems.