High-sensitivity integrated SiN rib-waveguide long period grating refractometer

In this research, we demonstrate a high-sensitivity integrated silicon nitride long period grating (LPG) refractometer based on rib waveguide with sinusoidally modulated width. While LPG architectures typically achieve ultrahigh sensitivity only over narrow optical bandwidth using phase-matching turning-point optimization technique, our sensor exhibits very high refractometric that was designed to remain constant broad operational spectral bandwidth. The proposed design method relies multi-modal dispersion tailoring consists of homogenizing the behaviors both group and effective indices coupling modes. Experimental results are in agreement numerical simulations, demonstrating not reaching 11,500 nm/RIU but, more significantly, also remains almost range at least 100 nm around 1550 nm. Additional advantages architecture encompass low temperature sensitivity, down ?0.15 nm/K, simplicity fabrication process. These feasibility chip-scale photonic integration large dynamic refractometer.