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We report on an experimental investigation of the five vibrational Raman lines at 358 nm, 388 nm, 391 nm, 428 nm, and 471 nm of N2+ resonantly driven by the self-seeding ionic lasers generated by a polarization-modulated (PM) or alternatively a linearly polarized (LP) femtosecond laser. click here It was found that the spectral intensities of several Raman lines can be dramatically enhanced by exploiting the PM laser pulses in comparison to the LP laser pulses. The evaluated Raman conversion efficiency reaches ∼10-2 for some lasing lines at suitable pressures. Moreover, the role of interplay between the seed amplification and the resonant vibrational Raman scattering processes in inducing the gain of N2+ lasing is characterized for the first time. The developed vibrational Raman spectroscopy with intense ultrafast lasers provides an additional approach to interrogate the products in a femtosecond filament, and it therefore can be a powerful tool for identifying chemical species at remote distances in the atmosphere.A highly efficient diode-pumped NdYVO4/KGW Raman yellow laser is developed to produce a 6.8 W yellow light at 579.5 nm accompanied by a 3.2 W Stokes wave at 1159 nm under an incident pump power of 30 W. The intracavity stimulated Raman scattering with the shift of 768cm-1 is generated by setting the polarization of the fundamental wave along the Ng direction of an Np-cut KGW crystal. The NdYVO4 gain medium is coated as a cavity mirror to reduce the cavity losses for the fundamental wave. More importantly, the KGW crystal is specially coated to prevent the Stokes wave from propagating through the gain medium to minimize the cavity losses for the Stokes wave.The propagation direction of edge states is essentially related to the band topology invariant of the constituent structures and the momentum of the excitation source. However, it is difficult to control the propagation path when the chirality of the excitation source and the boundary structures are determined. Here, we study a frequency selective waveguide structure based on photonic crystals with different topological invariant characterized by bulk polarization. By designing different types of interface made from spatially arranged dielectric rods, distinct topological edge states could be realized at different frequencies in the band gap. Therefore, we can construct a meta-structure in which the wave guiding path can be switched by the excitation frequency. Our study provides an alternative approach to designing topological devices such as frequency dependent optical waveguides and frequency division devices.Optical tweezers based on plasmonics experience a tremendous development on manipulating nanoparticles but are unable to avoid the problem of Joule heating. In this Letter, we report a silicon nanotrimer to optically trap and manipulate nanoparticles with negligible local heating. The optical forces and trapping potential of the nanotrimer are investigated using the finite-difference time-domain method. The results indicate that the trapping position can be shifted by tuning the polarization of the incident light. Furthermore, the silicon nanotrimer enables simultaneous trapping of multiple nanoparticles using circularly polarized illumination. Our work provides a promising building block for an integrated all-dielectric platform to realize optically driven nanomanipulation, which offers new possibilities for on-chip optical applications.This Letter presents a guided filtering (GF)-based nonlocal means (NLM) method for despeckling of optical coherence tomography (OCT) images. Unlike existing NLM methods that determine weights using image intensities or features, the proposed method first uses the GF to capture both grayscale information and features of the input image and then introduces them into the NLM for accurate weight computation. The boosting and iterative strategies are further incorporated to ensure despeckling performance. Experiments on the real OCT images demonstrate that our method outperforms the compared methods by delivering sufficient noise reduction and preserving image details well.The interaction of an ultra-intense laser with a solid state target allows the production of multi-MeV proton and ion beams. This process is explained by the target normal sheath acceleration (TNSA) model, predicting the creation of an electric field on the target rear side, due to an unbalanced positive charge. This process is related to the emission of relativistic ultrafast electrons, occurring at an earlier time. In this work, we highlight the correlations between the ultrafast electron component and the protons by their simultaneous detection by means of an electro-optical sampling and a time-of-flight diagnostics, respectively, supported by numerical simulations showing an excellent agreement.In this Letter, a 1×3 polarization-insensitive optical power splitter based on cascaded tapered silicon waveguides is proposed and experimentally demonstrated on a silicon-on-insulator platform. By utilizing the particle swarm optimization algorithm and the finite difference time domain method, the structural parameters of the coupling regions are carefully designed to achieve polarization-insensitive property, compact size, low insertion loss, high uniformity, and broad bandwidth. The coupling length can be as short as 7.3 µm. Our measurement results show that, at 1550 nm, the insertion losses of the fabricated device operating in transverse electric (TE) and transverse magnetic (TM) polarizations are, respectively, 0.068 dB and 0.62 dB. Within a bandwidth from 1525 to 1575 nm, the insertion loss is lower than 0.82 dB and the uniformity is less than 1 dB for the fabricated device operating in TE polarization, while the fabricated device operating in TM polarization can have an insertion loss smaller than 1.50 dB and a uniformity lower than 1 dB from 1528 to 1582 nm.This publisher’s note contains corrections to Opt. Lett.45, 5136 (2020)OPLEDP0146-959210.1364/OL.394137.Direct 2D spatial-coherence measurements are increasingly gaining importance at synchrotron beamlines, especially due to present and future upgrades of synchrotron facilities to diffraction-limited storage rings. We present a method to determine the 2D spatial coherence of synchrotron radiation in a direct and particularly simple way by using the Fourier-analysis method in conjunction with curved gratings. Direct photon-beam monitoring provided by a curved grating circumvents the otherwise necessary separate determination of the illuminating intensity distribution required for the Fourier-analysis method. Hence, combining these two methods allows for time-resolved spatial-coherence measurements. As a consequence, spatial-coherence degradation effects caused by beamline optics vibrations, which is one of the key issues of state-of-the-art X-ray imaging and scattering beamlines, can be identified and analyzed.