Performance enhancement of MXene derivatives-coated fiber humidity sensor via intensity-correlated twin beams

Here, we have theoretically proposed and experimentally demonstrated a sandwich-type (single-mode-no-core-single-mode, SNS) fiber-optic relative humidity sensor integrating a MXene derivatives coating and intensity-correlated twin beams, achieving high-sensitivity humidity sensing within a 30%-90% RH range by utilizing the unique quantum properties of the twin beams. This sensor utilizes the mechanism of water molecule adsorption-induced refractive index variation in the MXene derivatives coating, which modulates the constructive/destructive condition of multimode interference within the no-core fiber, thereby converting relative humidity variations into detectable optical signals. Furthermore, based on the aforementioned coating, intensity-correlated twin beams are introduced for the first time. In an unbalanced architecture, the system achieves a maximum signal-to-noise ratio enhancement of 0.831 dB during humidity increase and 0.834 dB during humidity decrease, corresponding to sensitivities of 0.3117 dB/%RH and 0.3179 dB/%RH, respectively, representing at least a 7.1-fold enhancement compared with classical single-channel humidity sensing. Moreover, in sealed-environment tests, the present sensor demonstrates a response time as fast as 1.56 s and a recovery time of 0.78 s. Its promising sensing performance offers a novel solution for applications such as medical diagnostics and industrial process control.