Highly efficient detection of near-infrared optical vortex modes with frequency upconversion

Abstract

Vortex beams carrying orbital angular momentum (OAM) have been widely applied in optical manipulations, optical micromachining, and high-capacity optical communications. Vortex mode detection is very important in various applications. However, the detection of near-infrared vortex modes is still difficult because of the wavelength limitations of the detection device. Here, we present a study on measuring optical near-infrared vortex modes with frequency upconversion, which can convert a near-infrared beam into a visible beam. In our experiment, the optical near-infrared vortex modes can be measured by the number and orientation of the fringes of the second harmonic intensity patterns. The proposed method is a convenient and flexible way to measure the different OAM of vortex beams, which may have potential applications in all kinds of circumstances that vortex modes involve.

Second-Harmonic Generation of the Vortex Beams with Integer and Fractional Topological Charges

“…Our results verify that the Rayleigh range of the SH beam is the same as that of the fundamental beam during the SHG process. The lobes of the SH beam obtained via the tilted lens method allow us to determine the TC carried by the fundamental infrared vortex beams [46]. In addition, we demonstrated that SHG is an effective method for obtaining vortex beams with high mode purity.…”

“…The power of the generated SH vortex beam and the transmi ed fundamental vortex beams is directly measured using two power meters (Thorlabs PM 100D). Both the off-axis interference method [49] and tilted lens method [46,50] are used to measure the TCs carried by the fundamental/SH vortex beams. For the former method, the TEM 00 Gaussian beam is used as the reference to interfere with the generated vortex beam with a small included angle.…”

The Spatial Mapping of Interconversion Between Laguerre-Gaussian and Hermite-Gaussian Beams Array With an Astigmatism Phase

“…al detected the vortex beam up to 100-order by employing this phase [22]. Furthermore, Yujia Wu and Yongqiang Yang extended this method to detect the OAM of the near-infrared optical vortex [23] and terahertz optical vortex [24], respectively. However, the conversion of the beams array is not analyzed in these reports.…”