We report a method to generate angularly polarized vector beams with a topological charge of one by rotating air holes to form two-dimensional photonic crystal (PC) cavities. The mode volume and resonance wavelength of these cavities are tuned from $0.33(\lambda /n)^3$0.33(λ/n)3 to $12(\lambda /n)^3$12(λ/n)3 and in a wide range of 400 nm, respectively, by controlling the range of fixed air holes near the center of the structure. As a benefit, the half-maximum divergence angles of the vector beam can be widely changed from 90° to $\sim60^\circ $∼60∘. By adjusting the shift direction of the air holes in the PC cavities, optical vector beams with different far-field morphology are obtained. The scheme provides not only an alternative method to generate optical vector beams, but also an effective strategy to control far-field morphology and polarizations, which holds promising applications such as optical microscopy and micro-manipulation.We demonstrated that ultrabroadband noise-like pulses (NLPs) spanning from below 1600 nm to beyond 2300 nm can be generated in Tm-doped fiber lasers enabled by an optical microfiber. Meanwhile, pronounced red light around 660 nm was also observed, which was attributed to the intracavity third harmonic generation (THG) of ultrashort pulses by harnessing the intermodal phase matching in the optical microfiber. As far as we know, it is the first time to simultaneously observe the ultrabroadband NLPs and the intracavity THG in ultrafast fiber lasers, and it is anticipated that these ultrabroadband NLPs can be adopted as a compact broadband source for optical spectroscopy around 2 µm and a wonderful potential seed for supercontinuum generation in the mid-infrared. Moreover, the THG of the intracavity high peak power NLPs in ultrafast fiber lasers provides a new kind of fiber-format visible light source.A nonlinear optical vortex coronagraph (n-OVC) based on sum-frequency generation (SFG) in a periodically poled lithium niobate (PPLN) crystal is presented. We demonstrate an n-OVC by mixing the image of an on-axis point source ($ \lambda _s = 1.6\;\unicodex00B5\rm m $λs=1.6µm) inside the PPLN crystal with a pump beam ($\lambda _p = 1064\;\rm nm$λp=1064nm) imprinted with a helical phase profile from a vector vortex mask (topological charge $l = 2$l=2). Due to quasi-phase matching and orbital angular momentum conservation, a coronagraphic image is produced at the SFG wavelength ($\lambda _\rm up\sim 630\;\rm nm$λup∼630nm). We validate that the n-OVC is tunable to signal wavelength but only requires a vortex mask operating at the pump wavelength. The acceptance bandwidth of the SFG process provides the n-OVC a degree of achromaticity even with a monochromatic vortex mask. The n-OVC exhibits an inner working angle of $ \sim \lambda _s/D$∼λs/D and an experimental contrast of $10^ - 4$10-4 at $3\lambda _s/D$3λs/D.It is still a technical challenge to obtain a 1.55 µm passively $Q$Q-switched $\rm Er^3 + /\rm Yb^3 + $Er3+/Yb3+ pulse laser with high energy and high repetition frequency, especially when it is end-pumped by a continuous-wave 0.98 µm diode laser. Benefitting from its long fluorescence lifetime of the $^4\rm I_13/2$4I13/2 upper laser level and high thermal conductivity, $\rm Er\rm Yb\rm Lu_2\rm Si_2\rm O_7$ErYbLu2Si2O7 crystal may be an excellent gain medium for realizing a high energy and high repetition frequency 1.55 µm pulse laser. At a continuous-wave absorbed pump power of 6.1 W, a 1537 nm pulse laser with energy of 45.5 µJ, repetition frequency of 1.32 kHz, and duration of 25 ns was first, to the best of our knowledge, realized in an $\rm Er\rm Yb\rm Lu_2\rm Si_2\rm O_7$ErYbLu2Si2O7 crystal.We report on a peculiar propagation of bosons loaded by a short Laguerre-Gaussian pulse in a nearly flat band of a lattice potential. Taking a system of exciton polaritons in a kagome lattice as an example, we show that an initially localized condensate propagates in a specific direction in space, if anisotropy is taken into account. This propagation consists of quantum jumps, collapses, and revivals of the whole compact states, and it persists given any direction of anisotropy. This property reveals its signatures in the tight-binding model, and, surprisingly, it is much more pronounced in a continuous model. Quantum revivals are robust to the repulsive interaction and finite lifetime of the particles. Since no magnetic field or spin-orbit interaction is required, this system provides a new kind of easily implementable optical logic.Structured illumination microscopy (SIM) is a powerful technique for providing super-resolution imaging, but its reconstruction algorithm, i.e., linear reconstruction structured illumination microscopy (LRSIM) algorithm in the Fourier domain, limits the imaging speed due to its computational effort. Here, we present a novel reconstruction algorithm that can directly process SIM data in the spatial domain. Compared to LRSIM, this approach uses the same number of frames to achieve a comparable resolution but with a much faster processing speed. Our algorithm was verified on both simulated and experimental data using sinusoidal pattern illumination. Moreover, this algorithm is also applicable for speckle pattern illumination.We report the experimental study of spectral modulations induced by a stimulated Raman scattering process in an all-fiber all-normal dispersion oscillator. With the use of dispersive Fourier transform, we recorded a series of single-shot spectra of consecutive laser pulses. The data indicate that the Raman process destabilizes the long-wavelength part of the laser pulse spectrum without disrupting the single-pulse generation regime. https://www.selleckchem.com/products/eft-508.html Our experiments revealed also that the oscillator displayed bistable operation for high pump powers. Two stable dissipative soliton mode-locked states were observed, together with output power hysteresis.Polarization imaging plays a crucial role in modern photonic applications such as remote sensing, material classification, and reconnaissance. A novel InGaAs focal plane array integrated with linear-array polarization grating is proposed and fabricated to meet the practical needs of near-infrared polarization imaging. In order to accurately evaluate the polarization performance of a fabricated detector, the improved test system is used to measure the transmittance and extinction ratio (ER). The results show that the detectivity reaches $1.06\; \times \;10^12\;\rm cm\cdot\rm Hz^1/2/\rm W$1.06×1012cm⋅Hz1/2/W, and the operable pixel factor is more than 99.8%. The transmittance of more than 55% and the ER of greater than 211 are realized, which indicates that the fabricated detector has excellent capability for near-infrared polarization imaging.