Single-pixel microscopy with photonic orbital angular momentum

Single-pixel imaging combines low cost, high sensitivity, and broad spectral adaptability, offering advantages for imaging beyond the visible spectrum. Leveraging the orbital angular momentum (OAM) of photons introduces a powerful degree of freedom, yet its application to single-pixel microscopy has been hindered by the challenge of high-dimensional complex OAM spectrum detection. Here, we exploit the conjugate symmetry of OAM eigenmodes, namely, Laguerre–Gaussian modes, and employ a unitary operation to decouple their intertwined phase and intensity profiles, thereby yielding detection modes that contain only intensity variations. This strategy enables direct single-pixel acquisition while fully eliminating the reliance on interferometric detection. Our method enables efficient sampling of fine details, achieves up to 4551-dimensional OAM spectrum measurements with 4.38 μm resolution, and uniquely supports functionalities such as region-of-interest imaging. These results establish a versatile framework that extends OAM to microscopic imaging and highlights its potential in multimode optical communication, quantum imaging, and non-visible spectral regimes.