Intensity modulation mechanism of parity-time symmetric photonic crystal coupled resonators

In order to study the application of transmission enhancement effect in photonic crystals, a novel sensing structure based on parity-time (PT) symmetry is proposed, in which a circular resonant cavity is introduced into the defect photonic crystal. By introducing the resonant cavity into the one-dimensional periodic photonic crystal with defect layer, the electric field is better localized in it, and the intensity of structural transmittance is greatly improved, namely transmission enhancement.Unlike the traditional optical sensing detection, the change of resonance peak caused by the detection quantity in the transmission spectrum is much more significant than the shift of resonance wavelength position, so the transmittance is used as the direct detection quantity. Through simulation and reasonable design of various structural parameters, the peak transmittance of the structure comes 400.7, the sensitivity reaches 1.34 x 105 RIU-1, which dramatically improves the detection sensitivity and changes the principle that the traditional optical sensor takes the shift of resonance wavelength as the direct detection quantity, so that the PT symmetry principle can be better applied to the optical structure.