Lab on Fiber: Sensing Characteristics of a Photonic Crystal Fabry−Perot Microcavity Structure Based on Two-Photon Polymerization Three-Dimensional Printing Technology

In this study, a photonic crystal Fabry−Perot microcavity (PCFPM) structure printed on the fiber end face was proposed and fabricated by using two-photon polymerization three-dimensional printing (TPP-3DP) technology. The PCFPM structure was designed by combining the PC structure with the FP interferometer. The simulation results showed that the PC structure indirectly enhances the response of the FP interferometer to the refractive index by regulating the optical field propagation characteristics. In the experiment, PCFPM was fabricated by the TPP-3DP technology. The experimental results indicated that the PCFPM structures with different lengths exhibited similar temperature and salinity responses. The temperature sensitivity of the PCFPM sensor reached 0.2486 nm/°C with a range of 5−40 °C. The salinity sensitivity of the PCFPM sensor reached 0.4870 nm/‰ with a range of 5‰−40‰, which is 2.23 times the theoretical value of the FP interferometer. The PCFPM sensor proposed had the advantages of simple preparation, small size, flexible structure, and high integration, which provided a new research direction for integrated photonic chips and contributed to the practical application of PC.