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We also established a model to analyze the nanostructures transition and to predict the dimensions of nanostructures. The simulation results demonstrate that the MFTE has an essential effect on the formation of nanostructures, which are in good agreement with the experimental results.In this paper, we study the secrecy performance of an energy-harvested relaying assisted free space optical-radio frequency (FSO-RF) network. In particular, a single-beam source sends an optical signal to a multi-aperture relay over an FSO channel, and then the relay converts it into an RF signal and adopts a decode-and-forward protocol to forward it to a multi-antenna destination under the wiretapping of a multi-antenna eavesdropper. We assume that the relay is power constrained, and it requires to harvest energy from a power beacon to assist the information transmission. It is also assumed that the FSO link and all RF links are subject to gamma-gamma fading with atmospheric turbulence and Rayleigh fading, respectively. Analytical expressions for secrecy outage probability (SOP) and the probability of strictly positive secrecy capacity are derived. In addition, the asymptotic expression for SOP is obtained to present insight into secrecy performance at high signal-to-noise ratio regimes. learn more Finally, Monte Carlo simulations verify the correctness of the theoretical derivations.Heat-assisted magnetic recording (HAMR), a new technique to overcome the data-density limitation, uses a laser to temporarily heat a nanovolume of a recording medium. Thus, this paper proposes a light delivery device that uses the metal/insulator/metal waveguide with a three-dimensional linear taper, and a grating added for an input, for HAMR. Our structure was calculated by finite-element method simulation. By design, 830 nm of light was delivered into a 50nm2 spot area with 63% coupling efficiency, and power intensity was enhanced 930 times. This achievement potential could be applied to the HAMR system in the future.An enhanced self-mixing interference (SMI) method in a laser diode (LD) based on a Fabry-Perot etalon (FPE) is presented. This method uses uncoated fused silica to form a FPE as a narrowband filter in the LD outer cavity, which can tune the laser wavelength to the edge of the FPE transmission spectrum profile to perform intensity demodulation. We compare the SMI signal based on the FPE filter with the conventional SMI signal. The experimental results show that the amplitude of the SMI signal based on the FPE filter is enhanced about 5 times in the range of 1 µm-5 µm; the displacement reconstruction errors are reduced by 30 nm; and the signal quality is significantly improved.In this study, we proposed a point diffraction interferometer based on birefringence polarization beam splitting (BPBS-PDI) for transmission wavefront measurements. Using the polarization beam splitting property of birefringent crystals and a specially designed calcite crystal as a polarization beam splitter, two beams of linearly polarized light with orthogonal polarization directions and a small angular separation can be obtained to produce the reference and test beams with perpendicular polarization directions through a pinhole point diffraction plate. By introducing spatial synchronization phase-shifting technology, influencing factors such as environmental vibrations on the measurement results, are reduced. Subsequently, the birefringent crystal and system error calibration methods were studied. Finally, a BPBS-PDI experimental device was set up to obtain the wavefront distribution of the lens to be tested. The experimental results are consistent with those of the ZYGO interferometer, indicating that the BPBS-PDI wavefront measurement method can be used to measure a lens transmission wavefront with high accuracy.Modern imaging optics ensures high-quality photography at the cost of a complex optical form factor that deviates from the portability. The drastic development of image processing algorithms, especially advanced neural networks, shows great promise to use thin optics but still faces the challenges of residual artifacts and chromatic aberration. In this work, we investigate photorealistic thin-lens imaging that paves the way to actual applications by exploring several fine-tunes. Notably, to meet all-day photography demands, we develop a scene-specific generative-adversarial-network-based learning strategy and develop an integral automatic acquisition and processing pipeline. Color fringe artifacts are reduced by implementing a chromatic aberration pre-correction trick. Our method outperforms existing thin-lens imaging work with better visual perception and excels in both normal-light and low-light scenarios.This paper presents a terahertz beamforming network based on a nonlocal lens with a 2D beam-scanning demonstration through leaky-wave antennas. The proposed design methodology is novel, to the best of our knowledge, in the aspect of using unconventional optimization parameters to significantly reduce the phase error associated with this class of beamformers. In this approach, a nonuniform contour defined by Fourier series expansion is used as a new optimization parameter to significantly decrease the phase error over a larger scan-angle than that in the previous works. The proposed system is a good candidate for industrial and security applications such as automotive radar sensors and electromagnetic THz imaging, thanks to its extensive 2D scanning range -68∘ to 0° in the elevation plane and -45∘ to +45∘ in the azimuth plane over the frequency range of 140-180 GHz.In this paper, an annular winding structure made of single-mode optical fiber is proposed as the core of a cost-efficient and reliable annular optical fiber temperature sensor (AOFTS). The sensor is mainly due to the multi-mode interference effect to achieve real-time response to external temperature changes. The experimental results show that the average temperature sensitivity of the sensor is about 255.5 pm/°C in the temperature range of -20∘C-110∘C; it has higher sensitivity at low temperatures. At -20∘C, the sensitivity of the AOFTS reaches 450 pm/°C. The sensor has the advantages of simple fabrication, low fabrication cost, strong stability, and good reproducibility and repeatability. It has great application prospects in the field of low-temperature detection.Amid the increasing potential of ultrafast mid-infrared (mid-IR) laser sources based on transition metal doped chalcogenides such as CrZnS, CrZnSe, and FeZnSe lasers, there is a need for direct and sensitive characterization of mid-IR mode-locked laser pulses that work in the nanojoule energy range. We developed a two-dimensional spectral shearing interferometry (2DSI) setup to successfully demonstrate the direct electric-field reconstruction of CrZnS mode-locked laser pulses with a central wavelength of 2.3 µm, temporal duration of 30.3 fs, and energies of 3 nJ. The reconstructed electric field is in reasonable agreement with an independently measured intensity autocorrelation trace, and the quantitative reliability of the 2DSI measurement is verified from a material dispersion evaluation. The presented implementation of 2DSI, including a choice of nonlinear crystal as well as the use of high-throughput dispersive elements and a high signal-to-noise ratio near-IR spectrometer, would benefit future development of ultrafast mid-IR lasers and their applications.This paper presents a what we believe is a novel method to fabricate turnaround point long-period gratings (TAP-LPGs) possessing enhanced thermal stability and high sensitivity. It is shown by analysis and by experiment that LPG resonance in photosensitive fibers can be controlled partially by UV fluence and thermal annealing. TAP-LPGs with enhanced thermal stability were fabricated by following three steps (I) finding grating period versus writing UV fluence for TAP operation; (II) writing gratings at a relatively higher period with higher fluence, in which case the resonance is out of phase; (III) controlled annealing so that the postannealed LPG operates at/near TAP. The thermal stability is enhanced. The average temperature sensitivity of dual peak resonance measured for a typical TAP-LPG in the temperature interval of 70°C-240°C is about 2.3 nm/°C. This study will be useful for the development of high temperature TAP-LPG sensors.In this paper, a joint communication interference integration signal waveform is proposed to satisfy the need of electronic system integration in civil and military uses, and mitigate the tension of spectrum resource. We design the system structure of the integrated signal model and propose the communication receiving processing flow of the integrated system. We utilize the dense false-target jamming style to raise the constant false alarm rate detection threshold via the delay superposition of multiple groups of frequency modulation (FM) slope mismatch jamming signals, which can play a role in protecting our target from being detected. Furthermore, linear frequency modulation (LFM) signals with different FM slopes and Doppler frequencies are obtained via the modulation mapping of communication data; thus, a single LFM signal can carry n bit data. Through correlation processing and frequency detection, code sequence information can be obtained to achieve communication function. The simulation results show that the integrated signal has the effect of shielding and jamming the pulse compression radar. Moreover, the system has a better bit error rate and a high communication rate, which can ensure that the communication task of sending accurate instructions is completed while implementing effective interference.Displacement measurement based on an image recognition algorithm has more advantages in the field of displacement measurement. Due to the uncertainty of image location, the accuracy of the displacement measurement algorithm studied in the previous stage is limited. To improve the accuracy of image-type displacement measurement, a high-precision displacement measurement algorithm based on depth fusion of the grating projection pattern is proposed. First, a line-scan image sensor and parallel light source are placed on both sides of the calibration grating. The marking pattern on the calibration grating is projected onto the image sensor through illumination of the parallel light source to realize the projection imaging. Then, the centroid algorithm is used to calculate the centroid of each line in the collected image, and the mean value of the centroid group is determined. Finally, a linear function is used to fit multiple centroids to calculate the endpoints of the subdivision region, and the subdivision operation is carried out according to a ratio algorithm. To test the performance of the proposed algorithm, a linear displacement measurement device with a 250 mm range and an angular displacement measurement device with a 100 mm diameter grating are both used for experiments. After testing, the linear measurement accuracy of the proposed algorithm is improved from 4.63 to 1.26 µm, and the angular displacement measurement accuracy is enhanced from 8.87 to 2.88. The research in this paper provides a theoretical basis for high-performance displacement measurement.