Scaling the performances of integrated long period grating refractometers

In this Letter, a theoretical analysis and design methodology of integrated long period gratings (LPGs) for refractometric applications are proposed. A detailed parametric analysis is applied to a LPG model based on two strip waveguides to highlight the main design variables and their effect on the refractometric performances, with focus on the spectral sen-sitivity and signature response. To illustrate the proposed methodology, four variants of the same LPG design are sim-ulated with eigenmode expansion, displaying a wide range of sensitivities up to 300,000 nm/RIU with figures of merit (FOMs) as high as 8000. (c) 2022 Optica Publishing Group

Automated summary

This Letter proposes a theoretical analysis and design methodology for integrated long period gratings (LPGs) in refractometric applications. A detailed parametric analysis is applied to a LPG model based on two strip waveguides to investigate the main design variables and their impact on refractometric performances, specifically spectral sensitivity and signature response. Simulations of four variants of the same LPG design using eigenmode expansion demonstrate a wide range of sensitivities up to 300,000 nm/RIU and figures of merit (FOMs) as high as 8000.