The supersensitive sensor of parity-time symmetry in coupled subwavelength resonator

To further achieve the sensing and measurement capabilities of supersensitive sensor, a method of combining PT symmetry and subwavelength metal spiral structure is proposed. Resistance elements are introduced into the resonant unit to achieve complex resonance frequencies and make the coupling system match PT symmetry conditions. By adjusting the distance between adjacent resonant units, we approach the exceptional point. Using the ultra-sensitive response to perturbation near the exceptional point, the ultra-sensitive sensing system is realized. Moreover, the theoretical analysis, numerical simulation and experimental measurement are carried out. The results show that, for a very small displacement of 0.05 wavelengths, the spoof surface plasmon measurement system based on PT symmetry can obtain greater frequency changes than the traditional measurement system, which confirms the prediction. The proposed system has the characteristics of construction, low profile, etc., which has a wide range of application prospects in construction engineering and construction detection.