Terahertz Refractive Index Sensing Based on Photonic Column Array

Terahertz (THz) silicon photonic column (PC) array has been designed and fabricated, and its resonance effect has been experimentally and numerically investigated. Using this resonance effect, the refractive index sensing for liquids has been demonstrated in this device by the theoretical model calculation, numerical simulation, and experimental measurement. Moreover, resonance dependence on different incident angles in this device has also been shown. These results confirm that this THz PC array can be used as a THz refractive index sensor with high sensitivity and robustness. This sensing strategy shows that the structured surface of this device is compatible for liquid monitoring and easy to couple and transmit THz waves, and therefore can be more easily implemented in liquid refractive index sensing.