Levinalbright0962

We describe topological edge solitons in a continuous dislocated Lieb array of helical waveguides. The linear Floquet spectrum of this structure is characterized by the presence of two topological gaps with edge states residing in them. A focusing nonlinearity enables families of topological edge solitons bifurcating from the linear edge states. Such solitons are localized both along and across the edge of the array. Due to the nonmonotonic dependence of the propagation constant of the edge states on the Bloch momentum, one can construct topological edge solitons that either propagate in different directions along the same boundary or do not move. This allows us to study collisions of edge solitons moving in opposite directions. LDC203974 molecular weight Such solitons always interpenetrate each other without noticeable radiative losses; however, they exhibit a spatial shift that depends on the initial phase difference.Three-dimensional (3D) range-gated imaging has great potential in underwater target detection, navigation, and marine scientific research due to good backscatter suppression. However, in turbid water, apparent backscatter leads to bad range resolution and accuracy in 3D reconstruction. To solve this problem, a 3D deblurring-gated range-intensity correlation imaging method is proposed based on light propagation property in water. In the method, only the water attenuation coefficient and a reference image are needed to calculate the depth-noise maps (DNM) of target gate images at different ranges. By subtracting the DNMs from target gate images, new gate images with less noise can be obtained, and then 3D images with high range resolution and accuracy are reconstructed. To prove the feasibility of the proposed method, experiments have been performed in pools under different water conditions. The results show that a higher peak signal-to-noise ratio improvement is about 9 dB in new gated images.In this Letter, we introduce a new kind of radially polarized beam called the radially polarized symmetric Airy beam (RPSAB). Compared to the linearly polarized symmetric Airy beam (SAB), the hollow focus spot of RPSAB enables it to trap a microparticle whose refractive index is lower than that of the surrounding medium, and the focus intensity of RPSAB is nearly three times higher than that of SAB under the same conditions. Also, we present the on-axis and off-axis radially polarized symmetric Airy vortex beam (RPSAVB). In the on-axis case, we find the maximum intensity of RPSAVB is about two times higher than that of RPSAB. For the off-axis case, we prove that slight misalignment of the vortex and RPSAB enables guiding the vortex into one of the self-accelerating channels, the same as the symmetric Airy vortex beam. Our results may expand the applications of RPSAB in laser cutting, metal processing, nanofocusing, and three-dimensional trapping of metallic Rayleigh particles.We present highly robust fiber Bragg gratings (FBGs) in passive large-mode-area fibers for kilowatt fiber laser systems. The gratings were inscribed directly through the fiber coating using near-infrared femtosecond laser pulses and then implemented in an all-fiber ytterbium-doped single-mode oscillator setup reaching up to 5 kW signal output power. The untreated cooled FBGs showed thermal coefficients as low as $1\;\rm K\;\rm kW^ - 1$1KkW-1, proving excellent qualification for the implementation into robust high-power fiber laser setups.Global acquisition of atmospheric wind profiles using a spaceborne direct-detection Doppler wind lidar is being accomplished following the launch of European Space Agency's Aeolus mission. One key part of the instrument is a single-frequency, ultraviolet laser that emits nanosecond pulses into the atmosphere. High output energy and frequency stability ensure a sufficient signal-to-noise ratio of the backscatter return and an accurate determination of the Doppler frequency shift induced by the wind. This Letter discusses the design of the laser transmitter for the first Doppler wind lidar in space and its performance during the first year of the Aeolus mission, providing valuable insights for upcoming space lidar missions.The dynamical parametric encirclement around a second-order exceptional point (EP) enables the time-asymmetric nonadiabatic evolution of light, which follows the chirality of the underlying system. Such light dynamics in the presence of multiple EPs and the corresponding chiral aspect is yet to be explored. In this Letter, we report a gain-loss assisted four-mode-supported optical waveguide that hosts a parameter space to dynamically encircle multiple EPs. In the presence of multiple EPs, we establish a unique nonadiabatic behavior of light, where beyond the chiral aspect of the system, light is switched to a particular mode, irrespective of the choice of the input mode. Proposed scheme certainly opens a step-forward approach in light manipulation to facilitate next-generation integrated photonic systems.Interaction between whispering gallery mode (WGM) resonators and nanoparticles is an area of active interest in fundamental understanding of nanoparticle-induced spectral modifications of the WGM resonances in sensing applications. Existing theories of this phenomenon assume that nanoparticles can be described taking into account only the electrodipole contribution to the field of the nanoparticle. In this paper, we explore theoretically the effects of the magnetodipole contribution to the nanoparticle's field and show that this contribution might become significant even in situations when electrodipole approximation is expected to remain valid.It is shown that Mueller-Jones matrices represent conformal Lorentz transformations. Thus the necessary and sufficient condition of a polarization device to be deterministic is to be describable by a conformal Lorentz transformation.We present the mechanism of backward Brillouin scattering induced by shear acoustic mode (SAM) in a step-index fiber. Unlike a longitudinal acoustic mode with negligible transverse displacement, a SAM has both considerable transverse and longitudinal displacements. During the light-sound coupling process, the fundamental and high-order SAMs can be guided and excited, ultimately generating a Brillouin gain spectrum with multipeak structure in a frequency range around 6 GHz. The interaction characteristics of the optical force with the displacement of all excited SAMs determine a partial cancellation effect, which is of great importance for the coupling coefficient of the optical-acoustic modes. The SAM-induced backward Brillouin scattering would provide a promising new approach for application such as multiparameter sensing.Polarimetric sensing/imaging by orthogonality breaking is a microwave-photonics-inspired optical remote sensing technique that was shown to be particularly suited to characterize dichroic samples in a direct and single-shot way. In this work, we expand the scope of this approach in order to gain sensitivity on birefringent and/or purely depolarizing materials by respectively introducing a circular or a linear polarization analyzer in the detection module. We experimentally validate the interest of these two new, to the best of our knowledge, induced orthogonality-breaking modalities in the context of infrared active imaging.We demonstrate a large-area red-emitting vertical-cavity surface-emitting laser (VCSEL) structure with significant improvement in the uniformity of charge carrier distribution by adopting a Si-doped $ \rm Al_0.20\rm GaInP $Al0.20GaInP current spreading layer and a bottom disk contact. The new structure emitting at 670 nm with a bottom disk contact diameter of 20 µm was compared with the conventional oxide-confined top-emitting structure with a similar aperture size. The maximum output peak power increased from 8.8 mW to 22.5 mW under pulsed-mode operation at room temperature. The far field improved from a strong multiple-mode pattern to a Gaussian-like profile. The corresponding divergence angle of the far-field pattern at $ 2\rm I_\rmth $2Ith injection current reduced from 16.2° to 10.9°.With an exact recursive approach, we study photonic crystal fibers and resonators with topological features induced by Aubry-Andre-Harper cladding modulation. We find nontrivial gaps and edge states at the interface between regions with different topological invariants. These structures show topological protection against symmetry-preserving local perturbations that do not close the gap and sustain strong field localization and energy concentration at a given radial distance. As topological light guiding and trapping devices, they may bring about many opportunities for both fundamentals and applications unachievable with conventional devices.A setup for an optical triangular-shaped pulse train with variable symmetry is proposed. The key component is an I/Q (I in-phase, Q quadrature phase) modulator. By properly setting the three variables, the optical intensity can be expressed by the sum of infinite sinusoidal harmonics, which indicates the possibility to approximate the asymmetrical waveform. It is found that the scheme is capable for generating an optical triangular-shaped pulse train with a tunable symmetrical coefficient ($20\% \le \delta \le 80\% $20%≤δ≤80%) and low fitting error ($\eta \le 6\% $η≤6%).A novel (to the best of our knowledge) photonic approach for the generation of background-free frequency-doubled phase-coded microwave pulses with immunity to periodic power fading is proposed. By switching between the carrier suppressed double sideband (CS-DSB) modulation with reverse quadrature phase difference and carrier suppressed single sideband (CS-SSB) modulation, background-free phase-coded microwave pulses with frequency doubling of the local oscillator signal can be obtained. Thanks to the CS-DSB/CS-SSB modulation, the generated microwave pulses can be directly transmitted via single-mode fiber (SMF) without the influence of the periodic power fading. Since no filter is utilized, the proposed scheme owns a wide frequency tunable range. An experiment is conducted to verify the proposed approach. Two 1 Gbit/s phase-coded microwave pulses with center frequencies of 6 and 12 GHz are generated and successfully transmitted through a 25 km SMF. The pulse compression ratio and main-to-sidelobe ratio after the transmissions are measured as 13 and 8.84 dB, respectively.Here, a deep learning (DL) algorithm based on deep neural networks is proposed and employed to predict the chiroptical response of two-dimensional (2D) chiral metamaterials. Specifically, these 2D metamaterials contain nine types of left-handed nanostructure arrays, including U-like, T-like, and I-like shapes. Both the traditional rigorous coupled wave analysis (RCWA) method and DL approach are utilized to study the circular dichroism (CD) in higher-order diffraction beams. One common feature of these chiral metamaterials is that they all exhibit the weakest intensity but the strongest CD response in the third-order diffracted beams. Our work suggests that the DL model can predict CD performance of a 2D chiral nanostructure with a computational speed that is four orders of magnitude faster than RCWA but preserves high accuracy. The DL model introduced in this work shows great potentials in exploring various chiroptical interactions in metamaterials and accelerating the design of hypersensitive photonic devices.