Simultaneously high-Q and high-sensitivity slotted photonic crystal nanofiber cavity for complex refractive index sensing

We proposed and theoretically investigated a one-dimensional slotted photonic crystal nanofiber cavity (SPCNC) for complex refractive index sensing in a gaseous environment. Three-dimensional finite-difference time-domain simulations show that a high quality factor (Q) of 1.45 x 10(6) and a high sensitivity of 756 nm/refractive index unit (RIU) can be simultaneously achieved for the detection of the real part of the refractive index (RI) of the surrounding gas. In addition, we demonstrated that the SPCNC possesses the capability of detecting the change of the imaginary part of the RI. A high sensitivity of 1525 nm/RIU is obtained, and Q is found to decrease with increasing absorption strength but still remains as high as 1.1 x 10(4) for strong absorption. We believe our proposed SPCNC with excellent sensing performances, ultra-small mode volume, and compact footprint may offer the potential to develop multiplexed sensing techniques for applications in multielement mixture detection. (C) 2017 Optical Society of America