Gryga M, Ciprian D, Gembalova L, Hlubina P
Opt Express. 2021 Apr 26;29(9):12996-13010. doi: 10.1364/OE.421162.
Sensing abilities of a one-dimensional photonic crystal (1DPhC) represented by a multilayer dielectric structure are analyzed theoretically and experimentally, using a new wavelength interrogation interference method. The structure comprising a glass substrate and six bilayers of TiO/SiO with a termination layer of TiO is employed in both gas sensing based on the Bloch surface wave (BSW) resonance and liquid analyte sensing based on a self-referenced guide-mode resonance (GMR). We model the spectral interference reflectance responses in the Kretschmann configuration with a coupling prism made of BK7 glass and show that a sharp dip with maximum depth associated with the BSW excitation is red-shifted as the refractive index (RI) changes in a range of 1-1.005. Thus, a sensitivity of 1456 nm per RI unit (RIU) and figure of merit (FOM) of 91 RIU are reached. Similarly, we model the responses for aqueous solutions of ethanol to show that dips of maximum depth are associated with the GMRs, and the highest sensitivity and FOM reached are 751 nm/RIU and 25 RIU, respectively. Moreover, we show that one of the dips is with the smallest shift as the RI changes, and hence it can be used as a reference. The theoretical results are confirmed by the experimental ones when the BSW resonance is used in sensing of humid air with a sensitivity of 0.027 nm/%relative humidity (RH) and FOM of 1.4×10 %RH. Similarly, the GMR is used in sensing of aqueous solutions of ethanol, and the highest sensitivity and FOM reached 682 nm/RIU and 23 RIU, respectively. The reference dip is also resolved and this self-reference makes the measurement more accurate and repeatable, and less sensitive to optomechanical drifts.
利用一种新的波长询问干涉方法，从理论和实验两方面分析了由多层介质结构表示的一维光子晶体（1DPhC）的传感能力。在基于布洛赫表面波（BSW）共振的气体传感和基于自参考导模共振（GMR）的液体分析物传感中，均采用了由玻璃衬底和六层TiO/Si双层膜以及一层TiO终端层组成的结构。我们对使用BK7玻璃制成的耦合棱镜的Kretschmann配置中的光谱干涉反射响应进行了建模，结果表明，随着折射率（RI）在1 - 1.005范围内变化，与BSW激发相关的具有最大深度的尖锐凹陷会发生红移。因此，实现了每RI单位（RIU）1456 nm的灵敏度和91 RIU的品质因数（FOM）。同样，我们对乙醇水溶液的响应进行了建模，结果表明，最大深度的凹陷与GMR相关，达到的最高灵敏度和FOM分别为751 nm/RIU和25 RIU。此外，我们还表明，其中一个凹陷在RI变化时的位移最小，因此可将其用作参考。当在湿空气传感中使用BSW共振时，实验结果证实了理论结果，其灵敏度为0.027 nm/%相对湿度（RH），FOM为1.4×10 %RH。同样，在乙醇水溶液传感中使用GMR，达到的最高灵敏度和FOM分别为682 nm/RIU和23 RIU。还分辨出了参考凹陷，这种自参考使得测量更加准确和可重复，并且对光机械漂移不太敏感。
