We report on a red praseodymium fiber laser delivering 1.07 W at 634.5 nm with a slope efficiency of 20.7% (versus the incident pump), a laser threshold of 0.55 W, and a single-mode output (Mx,y2 less then 1.1) in the quasi-continuous-wave regime. It is based on a 0.6 mol.% Pr3+-doped ZBLAN double-clad fiber with a 5.5 µm core, a double D-shaped (diameters, 115/125 µm) inner cladding, and a length of 5.0 m. The fiber is pumped by a multimode 443 nm GaN diode. The laser design is optimized using a numerical model. The proposed concept is suitable for the development of diode-pumped high brightness watt-level visible praseodymium fiber lasers.In this Letter, we introduce a new class of angular dependent autofocusing ring Pearcey beams by imposing a cross-phase structure. Due to this structure, the beam exhibits a non-uniform abrupt autofocusing behavior. Unlike the properties of the ring Pearcey beam without a cross phase [Opt. Lett.43, 3626 (2018)OPLEDP0146-959210.1364/OL.43.003626], we can flexibly adjust the focal length of the beam and its focusing ability, as well as the direction of the ring Pearcey beams, with the help of only the cross-phase structure. Furthermore, the Poynting vectors are employed to demonstrate convincingly the beam-focusing mechanism. Such beams with these fascinating characteristics are anticipated to find potential applications in optical tweezing, three-dimensional printing, material processing, and so on.In this Letter, we experimentally explore the propagation-dependent evolution of generating the pseudo-nondiffracting quasi-crystalline (crystalline) beams based on the multibeam interference. We originally derived an analytical formula to exactly manifest the propagation evolution of interfering multiple beams. With the analytical formula, the formation of quasi-crystalline structures in the focal plane can be explicitly verified. Furthermore, the distance of the effective propagation-invariant region can be verified in terms of experimental parameters. More importantly, we employed the developed formula to confirm the formation of kaleidoscopic vortex lattices by means of numerically computing the propagation-dependent phase singularities.Characterization of the complex spatiotemporal dynamics of optical beam propagation in nonlinear multimode fibers requires the development of advanced measurement methods, capable of capturing the real-time evolution of beam images. We present a new space-time mapping technique, permitting the direct detection, with picosecond temporal resolution, of the intensity from repetitive laser pulses over a grid of spatial samples from a magnified image of the output beam. By using this time-resolved mapping, we provide, to the best of our knowledge, the first unambiguous experimental observation of instantaneous intrapulse nonlinear coupling processes among the modes of a graded index fiber.We study the propagation dynamics of bright optical vortex solitons in nematic liquid crystals with a nonlocal reorientational nonlinear response. We investigate the role of optical birefringence on the stability of these solitons. In agreement with recent experimental observations, we show that the birefringence-induced astigmatism can eventually destabilize these vortex solitons. However, for low and moderate birefringence, vortex solitons can propagate stably over experimentally relevant distances.We show that slow light in hyperbolic waveguides is linked to topological transitions in the dispersion diagram as the film thickness changes. The effect appears in symmetric planar structures with type II films, whose optical axis (OA) lies parallel to the waveguide interfaces. The transitions are mediated by elliptical mode branches that coalesce along the OA with anomalously ordered hyperbolic mode branches, resulting in a saddle point. When the thickness of the film increases further, the merged branch starts a transition to hyperbolic normally ordered modes propagating orthogonally to the OA. In this process, the saddle point transforms into a branch point featuring slow light for a broad range of thicknesses, and a new branch of ghost waves appears.Nonlinear optical vibrational spectroscopies are powerful experimental tools for inspecting material properties that are difficult to acquire otherwise. As ultrafast lasers used in such experiments are typically of much broader bandwidth than vibrational modes, narrowband filtering is usually essential, and the utility of laser energy is often highly inefficient. Here we introduce an experimental scheme to break this trade-off. A broadband beam is spatially chirped as it reaches the sample, and generates sum-frequency signals upon overlapping with another broadband, unchirped beam. A narrowband spectrum can then be retrieved from the spatially dispersed image of signals, with both broadband pulses fully utilized. The scheme is also readily employed as a spatially resolved spectroscopy technique without scanning, and can be easily extended to other wave-mixing experiments.The optical properties of semiconductor quantum wells irradiated by a strong circularly polarized electromagnetic field are studied theoretically. Since the field can induce the composite electron-light states bound at repulsive scatterers, it drastically modifies all optical characteristics of the system. Particularly, it is demonstrated that the quantum interference of the direct interband optical transitions and the transitions through the light-induced intermediate states leads to the Fano resonances in the optical spectra, which can be detected in the state-of-the-art measurements.Resonator fiber optic gyroscope (RFOG) performance has hitherto been limited by nonlinearity, modal impurity, and backscattering in the sensing fibers. The use of hollow-core fiber (HCF) effectively reduces nonlinearity, but the complex interplay among glass and air-guided modes in conventional HCF technologies can severely exacerbate RFOG instability.  https://www.selleckchem.com/products/z-ietd-fmk.html  By employing high-performance nested anti-resonant nodeless fiber, we demonstrate long-term stability in a hollow-fiber RFOG of 0.05 deg/h, nearing the levels required for civil aircraft navigation. This represents a $3 \times$ improvement over any prior hollow-core RFOG and a factor of $500 \times$ over any prior result at integration times longer than 1 h.