Multimodal reflectivity of CRIGF filters: First experimental observation and modelling

Cavity Resonator Integrated Guided-mode Resonance Filter (CRIGF) are a new class of filtering reflectors whose selected wavelength and spectral width are independent of the angle of incidence unlike GMRF. These particular properties allow both compactness and a high angular acceptance. However, ours studies show that CRIGFs offer simultaneously spectral and modal filtering and we evidence high-spatial-order reflected modes. In this paper, we will present characterization of the spectral and spatial profile that demonstrates the existence of these high-order modes. In addition, we will present a model based on the physical understanding of implied phenomena to explain the experimental results. This model combines coupled-mode modelling and moiré fringes analysis. These modes could be harnessed for simultaneous spatial and spectral laser stabilization, to design and fabricate selective reflectors or outcouplers for spatial mode division multiplexing (SMDM) in few-mode fibers (FMFs) or for particles optical trapping.