Albrightmcintosh9826

The emergence of microwave self-biased metasurfaces with smart re-actions against incident waves with different power levels reveals great opportunities for designing smart windows, smart camouflage coating surfaces, and so on.A novel hologram conversion technique for speckle-less reconstruction is proposed. Many speckle-less reconstruction methods require holograms specially created for those techniques, limiting their applications to general pre-existing holograms. The proposed technique transforms an existing hologram with random phase distribution to new holograms for the application of the speckle-less reconstruction methods. Epigenetics inhibitor The proposed technique first extracts a set of orthographic views from the existing hologram, then the extracted orthographic views are processed for the speckle noise removal using convolutional neural network. The processed orthographic views are finally used to synthesize new holograms with desired carrier waves by using non-hogel based computer generated hologram technique. The selection of the carrier wave is determined by the desired speckle-less reconstruction method. In this paper, we demonstrate the proposed technique with two speckle-less reconstruction methods; i.e. temporal speckle averaging of different random phase distributions and time-multiplexing of interleaved angular spectrums.Fast imaging tracking technology exhibits attractive application prospects in the emerging fields of target tracking and recognition. Smart and compact tracking model with fast and flexible tracking strategy can play a decisive role in improving system performance. In this paper, an effective imaging tracking model from a target to a rotation Risley prism pair embedded with a camera is derived by the beam vector propagation method. A boresight adjustment strategy using the inverse ray tracing and iterative refinement method is established to accomplish the function of fast locating a target. The influence of system parameters on boresight adjustment accuracy and even the dynamic characteristics of the tracking system are investigated to reveal the coupling mechanisms between prism rotation and imaging feedback. The root-mean-square tracking error is below 4.5 pixels by just once adjustment in the static target experiment, while the error in the dynamic experiment is below 8.5 pixels for a target moving at the speed of 50 mm/s, which validates the feasibility of the proposed method for fast imaging tracking applications.Negative refraction (NR), self-collimation (SC), and zero refraction (ZR) effects of photonic crystals play an important role in beam steering. In this work, we report a multifunctional beam steering concept in photonic crystals, i.e., integrating two or three of the NR, SC, and ZR effects together at the same frequency. We find the square-lattice dielectric ring photonic crystal is an ideal candidate to realize the switchable function of ZR-SC while the square-lattice dielectric ring photonic crystal is more suitable for realizing the ZR-SC, ZR-NR, and ZR-SC-NR functions. The photonic band theory and an equivalent waveguide model are employed to explain these switchable functions in conventional and annular photonic crystals.Periodic surface gratings or photonic crystals are excellent tools for diffracting light and to collect information about the spectral intensity, if the target structure is known, or about the diffracting object, if the light source is well defined. However, this method is less effective in the case of extreme ultraviolet (XUV) light due to the high absorption coefficient of any material in this frequency range. Here we propose a nanorod array target in the plasma phase as an efficient dispersive medium for the intense XUV light which is originated from laser-plasma interactions where various high harmonic generation processes take place. The scattering process is studied with the help of particle-in-cell simulations and we show that the angular distribution of different harmonics after scattering can be perfectly described by a simple interference theory.An experimental platform operating at the level of individual quanta and providing strong light-matter coupling is a key requirement for quantum information processing. In our work, we show that hollow-core photonic bandgap fibers filled with laser-cooled atoms might serve as such a platform, despite their typical complicated birefringence properties. To this end, we present a detailed theoretical and experimental study to identify a fiber with suitable properties to achieve operation at the single-photon level. In the fiber, we demonstrate the storage and on-demand retrieval as well as the creation of stationary light pulses, based on electromagnetically induced transparency, for weak coherent light pulses down to the single-photon level with an unconditional noise floor of 0.017(4) photons per pulse. These results clearly demonstrate the prospects of such a fiber-based platform for applications in quantum information networks.The non-line-of-sight (NLOS) imaging problem has attracted a lot of interest in recent years. The objective is to produce images of objects that are hidden around a corner, using the information encoded in the time-of-flight (ToF) of photons that scatter multiple times after incidence at a given relay surface. Most current methods assume a Lambertian, flat and static relay surface, with non-moving targets in the hidden scene. Here we show NLOS reconstructions for a relay surface that is non-planar and rapidly changing during data acquisition. Our NLOS imaging system exploits two different detectors to collect the ToF data; one pertaining to the relay surface and another one regarding the ToF information of the hidden scene. The system is then able to associate where the multiply-scattered photons originated from the relay surface. This step allows us to account for changing relay positions in the reconstruction algorithm. Results show that the reconstructions for a dynamic relay surface are similar to the ones obtained using a traditional non-dynamic relay surface.This paper describes a theory for mode locking and frequency comb generation by four-wave mixing in a semiconductor quantum-dot active medium. The derivation uses a multimode semiclassical laser theory that accounts for fast carrier collisions within an inhomogeneous distribution of quantum dots. Numerical simulations are presented to illustrate the role of active medium nonlinearities in mode competition, gain saturation, carrier-induced refractive index and creation of combination tones that lead to locking of beat frequencies among lasing modes in the presence of cavity material dispersion.