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We numerically demonstrate a coherent pulse stacking of 128 pulses amplified in the large nonlinear amplification regime.

We propose a structure containing the micro-resonator and a silicon-rich nitride waveguide to obtain the coherent octave-spanning comb-like supercontinuum, which is excited in the micro-resonator firstly and then broadened in the waveguide.

Modulated by the spatial phase, Airy-like beams that possess the faster and better self-healing as well as the greater acceleration along the desired arbitrary trajectory are introduced. Airy-like beams have the strong spontaneous-focusing ability and the peak value of the focal plane is 5.4 times that of the initial plane when traveling along the quadratic function trajectory. Besides, the larger quadratic coefficient and the smaller constant term of the quadratic function can enhance the self-healing and the spontaneous-focusing of the beams. When the beams transmit along the snakelike trajectory, the original main lobe separates a new main lobe, and the energy will concentrate on the new main lobe. Airy-like beams, along a hyperbolic-secant trajectory, can remain non-diffraction over long distances. However, when traveling along a hyperbolic trajectory, the evolution process is very similar to that of Airy-Gaussian vortex beams. These excellent properties can be applied to the special beams’ modulation and optimization. Furthermore, it may provide a way for constructing beams along the special trajectory with the desired spontaneous-focusing and self-healing.

We numerically demonstrate supercontinuum generation in the silicon-organic hybrid waveguide can be improved significantly by a weak CW trigger. The CW-triggered supercontinuum exhibits a broader spectrum with a higher degree of temporal coherence. © 2020 The Author(s)

We propose an integrated structure with microresonator and slot waveguide to generate high performance supercontinuum harnessing dual-pump scenario. Compared with single pump of CW or soliton pulse, it possesses broader spanning and better coherence.

We address the propagation of vortex beams with the circular Airy–Gaussian shape in a ( 2 + 1 )-dimensional optical waveguide modeled by the fractional nonlinear Schrödinger equation. Systematic analysis of autofocusing of the beams reveals a strongly non-monotonous dependence of peak intensity in the focal plane on the corresponding Lévy index α , with a strong maximum at α ∼ 1.4 . Effects of the nonlinearity strength, the ratio of widths of the Airy and Gaussian factors in the input, as well as the beams’ vorticity on the autofocusing dynamics are explored. In particular, multiple autofocusing events occur if the nonlinearity is strong enough. Under the action of azimuthal modulational instability, an axisymmetric beam may split into a set of separating bright spots. In the case of strong fractality (for α close to one), the nonlinear beams self-trap, after the first instance of autofocusing, into a breathing vortical quasi-soliton. Radiation forces induced by the beams’ field are considered too, and a capture position for a probe nanoparticle is thus identified.

We introduce a new class of cosine complex variable function Airy–Gaussian (Cos-CVFAiG) beams and investigate their propagation through the gradient-index medium. Deriving the analytical expression, we show the intensity and phase distributions, the propagation trajectory and the Poynting vector. We carry out the numerical experiment to verify the rationality of the model and find that the light intensity distribution is parallel to the y axis in the transverse plane. With the distribution factor increasing, the axial intensity maximum and the number of the side lobes increase as well. Additionally, the distribution factor can change the bend extent of the ballistic trajectory and the intensity distribution region in the x–z plane. We also compare the influences of the gradient refractive index coefficient with the distribution factor on the propagation properties.

We propose an on-chip cascaded structure consisting of a microresonator and a slot waveguide to generate the high-performance supercontinuum harnessing the dual pump scenario. Utilizing a single CW pump with the power of only 0.1 W, the dissipative Kerr soliton with the full width at half maximum of 69.2 fs and the peak power of 103.3 W is generated and couples out the microresonator together with the CW pump to serve as a dual pump seed for the supercontinuum generation in the followed slot waveguide. The slot waveguide built upon a silicon-organic hybrid structure is carefully designed to possess remarkable nonlinearity and appropriate dispersion profile for smooth and broadband supercontinuum generation. We have numerically achieved the 1.56 octave-spanning supercontinuum spanning 1 ~ 3 μm with the proposed dual pump scenario. The supercontinuum generated by the dual pump scenario shows flattened, broadband, and quasi-right-angled-trapezoid shape, along with good coherence. Compared with the single pump scenario of CW or soliton pulse only, the supercontinuum generated by the dual pump scenario possesses the much stronger spectrum, broader spanning, and medium coherence. Our work opens up a new path for on-chip and cost-effective supercontinuum generation with the high performance of intensity, bandwidth, and coherence.

We introduce the propagation of the first-order chirped Airy vortex beams (FCAiV) in a chiral medium analytically. Results show that the FCAiV beams split into the left circularly polarized vortex (LCPV) beams and the right circularly polarized vortex (RCPV) beams, which have totally different propagation trajectories in the chiral medium. In this paper, we investigate the effects of the first-order chirped parameter β, the chiral parameter γ and the optical vortex on the propagation process of the FCAiV beams. It is shown that the propagation trajectory of the FCAiV beams declines with the chirped parameter increasing. Besides, the increase of the chiral parameter acting on the LCPV beams makes the relative position between the main lobe and the optical vortex further while the effect on the RCPV beams is the opposite. Furthermore, the relative position between the main lobe and the optical vortex contributes to the position of the intensity focusing. Meanwhile, with the chiral parameter increasing, the maximum gradient and scattering forces of the LCPV beams decrease but those of the RCPV beams will increase during the propagation. It is significant that we can control the propagation trajectory, the intensity focusing position and the radiation forces of the FCAiV beams by varying the chirped parameter and the chiral parameter.

By using the Huygens–Fresnel diffraction integral, we can obtain the analytical expressions of the chirped-Airy–Gaussian-vortex (CAiGV) beams propagating in the chiral medium. The distributions of the intensity, the phase and the gradient force of the CAiGV beams have been investigated analytically. Firstly, the CAiGV beams split into the left circularly polarized vortex (LCPV) beams and the right circularly polarized vortex (RCPV) beams when propagating in the chiral medium. We find that the values of the topological charges determine the focusing location, and the intensity distribution of the CAiGV beams is affected by the distribution factor χ 0 and the chiral parameter γ. With the increase of the chiral parameter γ, the parabolic deflection of the LCPV beams increases and that of the RCPV beams decreases, respectively. Similarly, if the chiral parameter γ increases, the evolution speed of the gradient force's distribution of the LCPV beams will speed up but that of the RCPV beams will slow down. In addition, the propagation trajectory and the diffraction effect of the beams are affected by the first-order and the second-order chirp parameters. Therefore, the propagation trajectory can be modulated effectively by adjusting the chiral parameter γ and the chirp parameters β 1 and β 2. Moreover, the phase distribution shows that the phase singularity moves outward and the trajectory approximates a straight line when the propagation distance increases. Finally, we find that the results of numerical experiments agree well with the analytical results.

We study both analytically and numerically nonparaxial propagation dynamics of the Chirped Airy vortex (CAiV) beams in uniaxial crystal orthogonal to the optical axis. The propagation trajectory, the intensity, the radiation forces, the Poynting vector and the angular momentum (AM) of the CAiV beams are illustrated by numerical examples. The influences of the ratio of the extraordinary refractive index to the ordinary refractive index, the linear chirp factor and the quadratic chirp factor on the nonparaxial evolution of the CAiV beams are examined in detail. Results show that the linear chirp factor provides an intensity concentration, which is totally different with the influence of the quadratic chirp. Besides, the uniaxial crystals with different refractive index ratios can be used to control the intensity of optical lobes. Moreover, the value and the direction of the radiation forces depend on the propagation distance and the chirp factor. The chirp factor acting on the Poynting vector and the AM mainly occurs in the direction of vectors. The nonparaxial propagation characteristics of the CAiV beams provide a convenient method to the intensity modulation and the optical manipulation of micro particles.