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We report a concise yet efficient experiment to extend the study of full Poincaré beams to incorporate the nonlinear optical effect. The main feature of our scheme is the employment of Type-II phase-matching KTP crystal to implement the second harmonic generation with structured vector light from invisible to visible region. Of particular interest is the revelation and visualization of the hidden topological structures transferred from the input polarization state to the output observable intensity patterns. The experimental results are in good agreement with the numerical simulations. Our present work provides us with the insight into the interaction of full Poincaré beams with media in the nonlinear regime.

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According to the concept of digital spiral imaging, we reconstruct an arbitrary structured light beam with information based on orbital angular momentum (OAM) eigenstates, i.e., the Laguerre-Gaussian (LG) modes. We propose a method to realize the rotation and reflection of an image by imparting an extra phase factor to each constituent OAM mode. If each OAM mode is added by a time-varying phase, the structured light beams can be manipulated to rotate with a constant speed, similar to a reverse rotational Doppler effect. While making a conjugate transformation to each OAM mode and then adding a constant phase factor to them, the structured light beams can be flipped over along any axis. In experiment, we take two typical patterns, e.g., a smiley face and a letter “e,” to demonstrate the effectiveness of our scheme. The scheme presented in this work may find potential applications in optical micromanipulation and remote sensing.

We present a scheme to produce the selected left or right elliptically polarized high-order harmonic generation. By adopting bichromatic counter-rotating colinear elliptically polarized pulses, their interaction with oxygen molecule are calculated under the framework of time-dependent density functional theory. Here we show that the helicity-selective high harmonics with tunable ellipticity are generated by changing the ellipticity of one of the pump pulses. Because of the interference of the degenerate highest occupied molecular orbitals, tunable ellipticity in a wide spectral range is obtained. This scheme can be used to synthesize attosecond pulses with controlled ellipticity and helicity.