Materials innovation for circularly polarized photodetectors

Circularly polarized light (CPL) features electromagnetic vectors that rotate regularly in a plane perpendicular to the direction of propagation, transmitting optical chirality information that is imperceptible to human beings. CPL can be classified into the left-handed and right-handed circularly polarization light (L-/R-CPL), depending on whether the rotation direction is clockwise or anticlockwise, respectively. The ability to manipulate and characterize CPL is crucial for advancing various optical technologies, making the effective and direct detection of CPL extremely important. Breeding in the hotbed provided by the explosively increased chiral materials with CPL luminescence and strong circular dichroism (CD), CPL detectors are currently experiencing savage growth. Mainstream strategies can be divided into the leverage of photoactive materials with inherent chirality and the integration of chiral metamaterials with nonchiral photoactive materials. In this review, we not only highlight significant material innovations and detector architectures for CPL detection but also address the broader implications of these advancements. We discuss the challenges and future directions in this field, particularly focusing on how these developments could impact existing commodities, such as polarimetric imaging and security communications, and contribute to sustainability in technology through improved detection efficiency. Our goal is to inspire further promising developments in CPL photodetectors and encourage a broader application spectrum.