Up-conversion detection of mid-infrared light carrying orbital angular momentum

TL;DR

This paper demonstrates efficient up-conversion of mid-infrared light carrying orbital angular momentum to visible wavelengths, enabling the use of standard detectors for advanced optical communication and sensing applications.

Contribution

It introduces a method to convert MIR OAM light to visible with high efficiency and verifies OAM conservation, advancing MIR light manipulation techniques.

Findings

Maximum quantum conversion efficiencies of 34.0%, 10.4%, and 3.5% for topological charges 0, 1, and 2.

Successful verification of OAM conservation through interferometry.

Potential applications in MIR optical communications and remote sensing.

Abstract

Frequency up-conversion is an effective method of mid-infrared (MIR) detection by converting the long-wavelength photons to the visible domain, where efficient detectors are readily available. Here, we generate the MIR light carrying orbital angular momentum (OAM) from a difference frequency generation process and perform the up-conversion of it via sum frequency conversion in a bulk quasi-phase-matching crystal. The maximum quantum conversion efficiencies from MIR to visible are 34.0%, 10.4%, and 3.5% for light with topological charges of 0, 1, and 2, respectively, which is achieved by utilizing an optimized strong pump light. We also verify the OAM conservation with a specially designed interferometer, and the results agree well with the numerical simulations. Our study opens up the possibilities for generating, manipulating, and detecting MIR light that carries OAM, and will have great potential for optical communications and remote sensing in the MIR regime.