To balance the accuracy and efficiency in multiple-view triangulation with sequential images, a high-efficiency propagation-based incremental triangulation (INT) method, carving three-dimensional (3D) scene points by updating the incoming feature track one by one without iterations, is proposed. Based on the INT method, a more accurate iteration-limited INT method is also established with few iterations to bound the propagated errors, ensuring the accuracy of subsequent 3D reconstruction. Finally, experimental results demonstrate that the proposed methods can balance the efficiency and accuracy in different multiple-view INT situations.

We propose a color ghost imaging approach where the object is illuminated by three-color non-orthogonal random patterns. The object’s reflection/transmission information is received by only one single-pixel detector, and both the sparsity constraint and non-local self-similarity of the object are utilized in the image reconstruction process. Numerical simulation results demonstrate that the imaging quality can be obviously enhanced by ghost imaging via sparsity constraint and non-local self-similarity (GISCNL), compared with the reconstruction methods where only the object’s sparsity is used. Factors affecting the quality of GISCNL, such as the measurement number and the detection signal-to-noise ratio, are also studied.

We report a spatially modulated polarimetry scheme by using a zero-order vortex half-wave retarder (ZVHR) and a spatial Fourier analysis method. A ZVHR is employed to analyze the input polarized light and convert it into a vectorial optical field, and an analyzer is set after the ZVHR to form an hourglass intensity pattern due to the spatial polarization modulation. Then, the input light’s Stokes parameters can be calculated by spatial Fourier analysis of the hourglass pattern with a single shot. The working principle of the polarimeter has been analyzed by the Stokes–Mueller formalism, and some quantitative measuring experiments of different polarization states have been demonstrated. The experimental results indicate that the proposed polarimeter is accurate, robust, and simple to use.

Copper (Cu) nanoparticles (NPs) are synthesized under the near-surface region of the Nd:Y3Al5O12 (Nd:YAG) crystal by direct Cu+ ions implantation. Subsequently, the monolithic ridge waveguide with embedded Cu NPs is fabricated by C4+ ions irradiation and diamond saw dicing. The nonlinear optical response of the sample is investigated by the Z-scan technique, and pronounced saturable absorption is observed at the 1030 nm femtosecond laser. Based on the obvious saturable absorption of Cu NPs embedded Nd:YAG crystal, 1 μm monolithic mode-locked pulsed waveguide laser is implemented by evanescent field interaction between NPs and waveguide modes, reaching the pulse duration of 24.8 ps and repetition rate of 7.8 GHz. The work combines waveguides with NPs, achieving pulsed laser devices based on monolithic waveguide chips.

The behavior of self-polarization emission in Nd:Y3Al5O12(YAG)/Cr4+:YAG lasers has been proved in some cases. However, the degree and direction of polarization were often sensitive and unstable. We experimentally observed different beam profiles versus the angle of the polarizer relative to the polarization direction of the laser. In order to explore the polarization mechanism, the dynamics of intracavity polarized eigenmodes was analyzed theoretically. Simulative results were well consistent with our experimental observations. It indicated that the linear self-polarization emission was a composite state rather than an intrinsic state. This study contributed to the improvement of the polarization stability in Nd:YAG/Cr4+:YAG passively Q-switched lasers.

In this Letter, we experimentally investigate fast temporal intensity dynamics and statistical properties of the cladding-pumped Er/Yb co-doped random Rayleigh feedback fiber laser (EYRFL) for the first time, to the best of our knowledge. By using the optical spectral filtering method, strong and fast intensity fluctuations with the generation of extreme events are revealed at the output of EYRFL. The statistics of the intensity fluctuations strongly depends on the wavelength of the filtered radiation, and the intensity probability density function (PDF) with a heavy tail is observed in the far wings of the spectrum. We also find that the PDF of the intensity in the central part of the spectrum deviates from the exponential distribution and has the dependence on the laser operating regimes, which indicates some correlations among different frequency components exist in the EYRFL radiation and may play an important role in the random lasing spectrum stabilization process.

To obtain short pulse width and high peak power laser, a 7 kHz sub-nanosecond microchip laser amplified by a grazing incidence double pass slab amplifier is experimentally demonstrated in this Letter. We use a compact side-pumped Nd:YVO4 bounce amplifier with grazing incidence beam for achieving high gains and power extraction. Laser output power of 7.37 W at 7 kHz, 1.2 MW pulse peak power with 877 ps duration and 1.05 mJ energy, 25 pm spectral width, and near diffraction limited mode beam quality are achieved, and the optical-to-optical efficiency is 18%. The laser is packaged in a volume of 356 mm × 226 mm × 84 mm and may be used for applications such as laser altimeters and ladar systems.

A retroreflector that reflects light along its incident direction has found numerous applications in photonics, but the available metasurface schemes suffer from the issue of narrow bandwidth and/or a single angle of incidence. Here, a retroreflector using double layers of achromatic gradient metasurfaces is reported, which can realize retroreflection over a continuous range of incidence angles within a wide spectral band. The first metasurface serves as a transmissive achromatic lens that performs a broadband spatial Fourier transform and its inverse, while the second metasurface works as a reflective achromatic lens that undergoes wavelength- and position-dependent phase dispersions. Using this design strategy, a near-infrared retroreflector comprised of silicon nanopillars with the cross sections of square pillars and square holes is numerically demonstrated, providing a high-performance retroreflection for polarization-independent incident light waves over a continuous range of incidence angles from 0° to 16° within an extremely broad wavelength range between 1.35 and 1.95 μm. The scheme herein can offer a design strategy of broadband retroreflectors and impact numerous photonics applications.

The temperature tuning of BaGa4Se7 (BGSe) was demonstrated for the first time, to the best of our knowledge. When the temperature of BGSe (56.3°,0°) was raised from 30°C to 140°C, the idler light under type I raised from 3637 nm to 3989 nm, the tunable range reached 352 nm, and Δλ2/ΔT reached 3.20 nm/°C. We calculated the phase matching curve of BGSe when ? and T took different values. The relationship between θ and Δλ2/ΔT was obtained by fixing ? at 0°. The maximum Δλ2/ΔT and its corresponding (θ, ?) phase matching type were reported under different fixed λ2 (3 μm, 3.2 μm,…, 5 μm).

Up-convertion (UC) perovskite Er3+-doped PbTiO3 (Er-PTO) nanoparticles with green and red emissions were synthesized via the hydrothermal method. The UC properties were manipulated by adjusting the concentration of Er3+ ions dopant. The green emission intensity was decreased as the doping concentration increased from 1% to 4% (mole fraction), whereas the red emission intensity was increased. The influences of Er3+ ions on the temperature-sensing performance were further investigated. The results demonstrated that Er-PTO nanoparticles with doping 1% Er3+ ions possessed a sensitivity of 3.1 × 10-3 K-1 at 475 K, presenting a high potential in optical heating devices.

The article is devoted to the technology for obtaining optical ceramics of AgBr-TlI and AgBr-TlBr0.46I0.54 systems and manufacturing samples with different compositions. The new heterophase crystal ceramics are transparent without absorption windows in the spectral range from 1.0 to 60.0 μm. In the ceramics’ transparency spectra based on the AgBr-TlI and AgBr-TlBr0.46I0.54 systems fusibility diagrams, with an increase in the thallium halides mass fraction, as well as the replacement of the bromine ion with iodine, the maximum transparency shifts to a long infrared region.

The evolution of the spin density vectors (SDVs) is studied in a strongly focused composite field. It is found that the SDVs can be spiral along the propagation axis, and they are perpendicular to the ys direction on the ys axis. This behavior is governed by the Gouy phase difference between the field polarization components. The 60° rotation of the spatial distribution of the transverse SDVs is also generated, which is found to be controlled by the Gouy phase difference between the field orbital angular momentum modes. Additionally, the spin density singularities are observed in the evolution of the SDVs.

The unevenly distributed Lorentz–Gaussian beams are difficult to reproduce in practice, because they require modulation in both amplitude and phase terms. Here, a new linearly polarized Lorentz–Gauss beam modulated by a helical axicon (LGB-HA) is calculated, and the two various experimental generation methods of this beam, Fourier transform method (FTM) and complex-amplitude modulation (CAM) method, are depicted. Compared with the FTM, the CAM method can modulate the phase and amplitude simultaneously by only one reflection-type phase-only liquid crystal spatial light modulator. Both of the methods are coincident with the numerical results. Yet CAM is simpler, efficient, and has a higher degree of conformance through data comparison. In addition, considering some barriers exist in shaping and reappearing the complicated Lorentz–Gauss beam with heterogeneous distribution, the evolution regularities of the beams with different parameters (axial parameter, topological charge, and phase factor) were also implemented.

Encoding information using the topological charge of vortex beams has been proposed for optical communications. The conservation of the topological charge on propagation and the detection of the topological charge by a receiver are significant in these applications and have been well established in free-space. However, when vortex beams enter a diffuser, the wavefront is distorted, leading to a challenge in the conservation and detection of the topological charge. Here, we present a technique to measure the value of the topological charge of a vortex beam obscured in the randomly scattered light. The results of the numerical simulations and experiments are presented and are in good agreement. In particular, only a single-shot measurement is required to detect the topological charge of vortex beams, indicating that the method is applicable to a dynamic diffuser.

Fresnel incoherent correlation holography (FINCH) is a well-established incoherent imaging technique. In FINCH, three self-interference holograms are recorded with calculated phase differences between the two interfering, differently modulated object waves and projected into a complex hologram. The object is reconstructed without the twin image and bias terms by a numerical Fresnel back propagation of the complex hologram. A modified approach to implement FINCH by a single camera shot by pre-calibrating the system involving recording of the point spread function library and reconstruction by a non-linear cross correlation has been introduced recently. The expression of the imaging characteristics from the modulation functions in original FINCH and the modified approach by pre-calibration in spatial and polarization multiplexing schemes are reviewed. The study reveals that a reconstructing function completely independent of the function of the phase mask is required for the faithful expression of the characteristics of the modulating function in image reconstruction. In the polarization multiplexing method by non-linear cross correlation, a partial expression was observed, while in the spatial multiplexing method by non-linear cross correlation, the imaging characteristics converged towards a uniform behavior.