Highly Sensitive Refractive Index Sensing Based on Photonic Spin Hall Effect and Its Application on Cancer Detection

The photonic spin Hall effect (SHE), manifesting itself as a spin-dependent splitting of left- and right-handed circularly polarized light, exhibits unique potential for nanophotonic devices, precise metrology and optical sensors. This work presents an original design of refractive index sensor for the cancer detection based on novel photonic SHE. The device consists of BK7 prism, monolayer graphene, glass substrate, and the analyte layer, in which the cell solution is introduced. Three groups of human normal (gastric, liver, epidermal) cells and corresponding cancer cells were chosen for the discrimination. The external optical pumping is applied on monolayer graphene in order to flexibly modulate the photonic SHE, and then the sensing performance can be accordingly tuned. It is found that the proposed sensor can not only discriminate the normal cells and cancer cells, but also distinguish the cancer cells for different concentrations. The superior intensity sensitivity of ${6.1} \times {10}^{{5}} \,\,\mu \text{m}$ /RIU for discriminating the gastric normal and cancer cells can be generated under the optimal pumping power, which is four orders of magnitude greater than previous reported sensors based on the resonant optical tunneling effect. These findings may provide practical applications in medical diagnose, drug discovery and cellular pathological analyse.