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We present a novel method, to our knowledge, to synthesize non-trivial speckle patterns that can enable sub-Rayleigh second-order correlation imaging. The speckle patterns acquire a unique anti-correlation in the spatial intensity fluctuation by introducing the blue noise distribution on spatial Fourier power spectrum to the input light fields through amplitude modulation. Illuminating objects with the blue noise speckle patterns can lead to a sub-diffraction limit imaging system with a resolution more than three times higher than first-order imaging, which is comparable to the resolving power of ninth order correlation imaging with thermal light. Our method opens a new route towards non-trivial speckle pattern generation by tailoring amplitudes in spatial Fourier power spectrum of the input light fields and provides a versatile scheme for constructing sub-Rayleigh imaging and microscopy systems without invoking complicated higher-order correlations.Multiplexed fiber optic Fabry-Perot interferometer (FPI) sensors are well known for their precision, simple construction, simpler wiring, and high sensing qualities. However, the limitations on existing demodulation methods degrade the measurement accuracy of multiplexed FPI sensors and necessitate large cavity length differences. In this paper, we propose an adaptive high-precision demodulation method based on vector matching and cluster-competitive particle swarm optimization (CCPSO), which transforms cavity length demodulation into searching for the global extreme. The proposed CCPSO, which uses agglomeration within clusters and competition between clusters simultaneously, enables the improvement of the global extreme search capabilities. The theoretical analysis and experimental results show that the proposed demodulation method decreases the lower limit of the needed cavity length differences to 22 μm, which is reduced by 76.9% compared with the fast Fourier transform-based method. An accuracy of 1.05 nm is achieved with a cavity length difference of 27.5 μm and a signal-to-noise ratio of 36.0 dB for the noise.Phase retrieval approaches based on deep learning (DL) provide a framework to obtain phase information from an intensity hologram or diffraction pattern in a robust manner and in real-time. However, current DL architectures applied to the phase problem rely on i) paired datasets, i. e., they are only applicable when a satisfactory solution of the phase problem has been found, and ii) the fact that most of them ignore the physics of the imaging process. Here, we present PhaseGAN, a new DL approach based on Generative Adversarial Networks, which allows the use of unpaired datasets and includes the physics of image formation. The performance of our approach is enhanced by including the image formation physics and a novel Fourier loss function, providing phase reconstructions when conventional phase retrieval algorithms fail, such as ultra-fast experiments. Thus, PhaseGAN offers the opportunity to address the phase problem in real-time when no phase reconstructions but good simulations or data from other experiments are available.A mechanically robust metasurface exhibiting plasmonic colors across the visible and the near-IR spectrum is designed, fabricated, and characterized. Thin TiN layers (41 nm in thickness) prepared by plasma-enhanced atomic layer deposition (ALD) are patterned with sub-wavelength apertures (75 nm to 150 nm radii), arranged with hexagonal periodicity. These patterned films exhibit extraordinary transmission in the visible and the near-IR spectrum (550 nm to 1040 nm), which is accessible by conventional Si CCD detectors. The TiN structures are shown to withstand high levels of mechanical stresses, tested by rubbing the films against a lint-free cloth under 14.5 kPa of load for 30 minutes, while structures patterned on gold, a widely used plasmonic material, do not. The subwavelength nature of the plasmonic resonances, coupled with robustness and durability of TiN, makes these structures an attractive choice for use in nanoscale security features for heavily handled objects. Furthermore, ALD of these films enables scalability, which in conjunction with the cost-effectiveness of the process and material (TiN) makes the entire process industry friendly.In this work, a Monte Carlo ray-tracing model for the simulation and optimization of a fiber Luminescent Solar Concentrator (LSC) based on stacked layers of fiber arrays is developed and validated. The fiber LSC efficiency improvements are compared against a conventional planar LSC. We developed a new model to analyze the performance of different configurations of bulk-doped fibers and fibers constituted by a doped coating and a passive core. These configurations are analyzed also varying fiber packing geometry diameters, and length. Due to the exceptionally low absorption coefficient of the silica fibers (αwg ≈ 10-4 cm-1), concentration factors of up to 1.9 are predicted when dimensions are scaled over 1 m2, which improve more than twice the maximum concentration factor ever reported. These results serve as a preliminary theoretical study for the future development of a new LSC design based on flexible silica micro-fibers coated with Si-QDs doped poly(lauryl methacrylate) (PLMA) layers.A highly productive ablation process of 100 nm thick platinum films with a processed area rate of up to 378 cm2/min is presented using radially and azimuthally polarized laser beams. This was achieved by developing a laser amplifier generating 757 fs long laser pulses at a maximum average power of 390 W and a repetition rate of 10.6 MHz with adjustable polarization states, i.e., linear, radial, and azimuthal polarization on the work piece. The pulse train emitted from the laser was synchronized to a custom-designed polygon scanner and directed into an application machine.In this paper, we propose and design a multi-orbital-angular-momentum multi-ring air-core fiber, which has seven high-index rings with each ring supporting 62 radially fundamental OAM modes across C and L bands (from 1530 nm to 1625 nm), i.e. 434 OAM modes in total. The designed fiber features >4×10-4 intra-ring modal indices difference for OAM modes with the same topological charge l in a ring across the C and L bands. Moreover, it can keep less then -52 dB crosstalk between the OAM modes in the adjacent rings at 1550 nm, and less then -24 dB crosstalk across C and L bands after 100-km fiber propagation. This kind of seven-air-core-ring fiber would be a robust candidate for transmitting efficient OAM modes and boosting the capacity of optical fiber communications systems.In this work, we study topological edge and corner states in two-dimensional (2D) Su-Schrieffer-Heeger lattices from designer surface plasmon crystals (DSPCs), where the vertical confinement of the designer surface plasmons enables signal detection without the need of additional covers for the sample. In particular, the formation of higher-order topological insulator can be determined by the two-dimensional Zak phase, and the zero-dimensional subwavelength corner states are found in the designed DSPCs at the terahertz (THz) frequency band together with the edge states. Moreover, the corner state frequency can be tuned by modifying the defect strength, i.e., the location or diameter of the corner pillars. This work may provide a new approach for confining THz waves in DSPCs, which is promising for the development of THz topological photonic integrated devices with high compactness, robustness and tunability.We fabricated a fiber-optic directional coupler based on evanescent field coupling between side-polished large mode area (LMA) double clad fibers (DCFs) for a high power fiber laser. The tapping ratio of the fabricated coupler was measured to be - 32 dB. The fundamental mode coupled in a core of the lower side-polished fiber (SPF) was transferred to the upper SPF without clad-mode coupling. Two SPFs were directly faced to increase an optical handling power up to 740 W. The tapping ratio of the coupler was constantly maintained at the applied laser output. The beam quality of the l aser including the fabricated coupler was maintained to be 1.22, without mode distortion by the coupler.We propose and experimentally demonstrate a microwave frequency measurement system based on the photonic technique. An amplitude comparison function is constructed to perform frequency-to-power mapping based on a non-sliced broadband optical source. The results are fed into a machine learning module which can be utilized to minimize the differential mode noise of the system caused by the polarization fluctuation. The system is reconfigurable with adjustable measurement bandwidth by adjusting the dispersion group delay of the signals at orthogonal polarizations by a polarization division multiplexed emulator (PDME). In addition, the mapping relationship is reconstructed by stacking method. The results are fed into four machine learning models support vector regressor (SVR), KNeighbors regressor (KNN), polynomial regressor (PR) and random forest regressor (RFR). https://www.selleckchem.com/products/AZD0530.html The output of the four models then combined by adding them together using linear regression method. By fitting the relationship between frequency and microwave power ratio with machine learning method, the accuracy of microwave frequency measurement system is further improved. The results show that for a measurement system with a bandwidth of 2 GHz and 4 GHz, the maximum error and the average measurement errors are all reduced. The results are promising for applications of modern radar and electronic warfare systems.The single-shot spatiotemporal characterization of an ultrahigh intensity laser pulse was performed using a multispectral wavefront sensor. For the measurement of the spatio-spectral electric field, a femtosecond laser pulse was spectrally modulated and separated by a Fabry-Perot etalon coupled with a grating pair, and its spatio-spectral electric field was measured with a wavefront sensor. The spatiotemporal electric field was reconstructed from the measured spatio-spectral electric field of a multi-PW laser pulse. We found that the spatiotemporal distortion could reduce the focused laser intensity by 15%, compared to the case of a diffraction-limited and transform-limited laser pulse.We report on a compact optical frequency comb, operating in the wavelength range from 670 to 1500 nm, based on diode-pumped low-noise femtosecond YbCALGO amplified laser system. Both the carrier-envelope offset and repetition rate are phase-locked to reference synthesizers. A full characterization of the frequency comb, in terms of frequency stability, phase noise analysis, and optical beating against a single-frequency non-planar ring oscillator NdYAG laser, is presented, showing the excellent properties of the YbCALGO comb.We measured angle-resolved reflection spectra of triangular-lattice photonic crystal slabs fabricated in a silicon-on-insulator wafer in the mid-infrared region. We achieved a high angle-resolution measurement by means of our homemade optical setup integrated in the sample chamber of an FT-IR spectrometer. By examining the reflection peak frequency as a function of the lateral component of the wave vector of the incident light and applying the selection rules expected from the spatial symmetry of electromagnetic eigenmodes in C6v-symmetric structures, we successfully obtained the dispersion relation and the mode symmetry of the photonic crystal slabs, which agreed well with numerical calculations by the finite element method. We also found the redistribution of diffraction loss between A1- and E1-symmetric modes, which was caused by the Dirac-cone formation due to their effective degeneracy.
