Complete chiroptical signal detection using weak measurement with intensity-contrast-ratio pointers

Chiroptical signals, including optical rotation (OR) and circular dichroism (CD), are widely utilized as potent probes for investigating the structure and properties of chiral molecules. However, acquiring both coexisting weak OR and CD signals simultaneously in a single measurement process with a high precision remains a challenge for conventional setups. In this article, a high-precision yet easy-to-set-up method for simultaneous detection of OR and CD signals based on weak measurement is theoretically and experimentally demonstrated. In addition, the chiroptical signals are detected using two new intensity-contrast-ratio pointers, which provide an expanded measurement range compared with the shift of the mean value pointer. The proposed method has been validated through a spin Hall effect light based experiment, with precision reaching the order of 10−7 and 10−6 rad for the detection of OR and CD, respectively. These results may serve as a catalyst for further studies of fast, multi-parameter biosensing technologies with ultra-precision.