This study investigated a novel polarisation detection model based on the microstructure of rhabdom in mantis shrimp eyes, in which a single unit can detect two directions of orthogonal polarisation. The bionic model incorporated multi-layered orthogonal Si wire grids, and the finite-difference time-domain method was used to simulate light absorption. A single-layer Si wire grid was simulated to study the effects of thickness and duty cycle on extinction ratios. A multi-layer orthogonal wire grid was simulated to study the effects of distance between adjacent layers. The simulations revealed that the bionic model can achieve orthogonal polarisation detection. Additionally, for 600 coupled layers, the extinction ratios in both directions were greater than 60, and light absorption in the absorptive directions exceeded 96%.