Highly Sensitive Refractive Index Sensor Based on Bragg Grating in Metallic-Hole Microstructured Optical Fiber

We present a theoretical comparative study of a highly sensitive Bragg grating sensor written in a microstructured optical fiber with bare and metallic voids or holes. Based on the full vector effective index method and the coupled mode theory our simulations show that the device is maximum sensitive for small metal thickness showing nearly double sensitive at 10 nm metal thickness as compared to that for the bare hole. This highest sensitivity is comparable to the maximum sensitivity reported for the pure surface plasmon polariton based Bragg gratin sensors and, unlike the later, the modes are easy to excite for the present sensor. Owing to the reflective mode operation the device is ideally suited for highly sensitive, remote deep sea and oil well sensing applications.