Tunable diffraction-free array in nonlinear photonic crystal

Abstract

Diffraction-free beams have attracted increasing research interests because of their unique performances and broad applications in various fields. Although many methods have been developed to produce such beams, it is still challenging to realize a tunable non-diffracting beam. Here, we report the generation of a tunable diffraction-free array through second-harmonic generation in a nonlinear photonic crystal, i.e., a 2D periodically-poled LiTaO3 crystal. In such a crystal, the second-harmonic wave is engineered by properly designing the domain structure based on the Huygens-Fresnel principle. The characteristics of the generated diffraction-free array including its period, propagation length, and wavelength can be tuned by simply changing the input wavelength. Our observation not only enriches the diffraction-free optics, but also has potential applications for photolithography and imaging.

Efficient nonlinear beam shaping in three-dimensional lithium niobate nonlinear photonic crystals

“…1a). This configuration has been applied to generate SH vortex beam, nonlinear superfocusing spot, SH non-diffracting beam, etc 27–29,32–34 . Unfortunately, the conversion efficiencies are typically below 1 × 10 −6 in a mm-long sample due to the lack of phase matching and the use of a small nonlinear coefficient d 22 of the LiNbO 3 crystal, which badly hampers the practical applications of nonlinear beam shaping.

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Broadband Variable Meta-Axicons Based on Nano-Aperture Arrays in a Metallic Film

“…In reality, we can only produce reasonably well-approximated Bessel beams with little or no diffraction over limited propagation distances. These beams have been explored for use in numerous fields, including nonlinear optics 2 , 3 , ultrasonic medical diagnosis 4 , optical trapping 5 , telescopes 6 and optical communications applications 7 , 8 . In particular, high-order Bessel beams have been attracting increasing interest because they can carry the orbital angular momentum (OAM) of light 9 , 10 .…”