It is a grand challenge for an imaging system to simultaneously obtain multi-dimensional light field information, such as depth and polarization, of a scene for the accurate perception of the physical world. However, such a task would conventionally require bulky optical components, time-domain multiplexing, and active laser illumination. Here, we experimentally demonstrate a compact monocular camera equipped with a single-layer metalens that can capture a 4D image, including 2D all-in-focus intensity, depth, and polarization of a target scene in a single shot under ambient illumination conditions. The metalens is optimized to have a conjugate pair of polarization-decoupled rotating single-helix point-spread functions that are strongly dependent on the depth of the target object. Combined with a straightforward, physically interpretable image retrieval algorithm, the camera can simultaneously perform high-accuracy depth sensing and high-fidelity polarization imaging over an extended depth of field for both static and dynamic scenes in both indoor and outdoor environments. Such a compact multi-dimensional imaging system could enable new applications in diverse areas ranging from machine vision to microscopy.

While conventional photodetectors can only measure light intensity, the vectorial light field contains much richer information, including polarization and spectrum, that are essential for numerous applications ranging from imaging to telecommunication. However, the simultaneous measurement of multi-dimensional light field information typically requires the multiplexing of dispersive or polarization-selective elements, leading to excessive system complexity. Here, we demonstrate a near-infrared spectropolarimeter based on an electrically-tunable liquid crystal metasurface. The tunable metasurface, which acts as an encoder of the vectorial light field, is tailored to support high-quality-factor guided-mode resonances with diverse and anisotropic spectral features, thus allowing the full Stokes parameters and the spectrum of the incident light to be computationally reconstructed with high fidelity. The concept of using a tunable metasurface for multi-dimensional light field encoding may open up new horizons for developing vectorial light field sensors with minimized size, weight, cost, and complexity.

The combination of conventional polarization optical elements, such as linear polarizers and waveplates, is widely adopted to tailor light’s state of polarization (SOP). Meanwhile, less attention has been given to the manipulation of light’s degree of polarization (DOP). Here, we propose metasurface-based polarizers that can filter unpolarized incident light to light with any prescribed SOP and DOP, corresponding to arbitrary points located both at the surface and within the solid Poincaré sphere. The Jones matrix elements of the metasurface are inverse-designed via the adjoint method. As prototypes, we experimentally demonstrated metasurface-based polarizers in near-infrared frequencies that can convert unpolarized light into linear, elliptical, or circular polarizations with varying DOPs of 1, 0.7, and 0.4, respectively. Our Letter unlocks a new degree of freedom for metasurface polarization optics and may break new ground for a variety of DOP-related applications, such as polarization calibration and quantum state tomography.