Study of the resonant behavior of waveguide-gratings Increasing the angular tolerance of guided-mode filters

Studies of anomalies of the reflection and transmission curves of waveguide-gratings have demonstrated unique filtering capabilities of these structures. Vincent and Neviere [1] showed that the excitation of a leaky mode in the system can lead to 100% reflectance at a given wavelength under certain condition of symmetry. A comparative study of guided-mode resonance filters with classical multilayers design shows that the latter requires considerably more layers to yield equivalent narrow-band linewidths [2]. However, contrary to thin-films filters, waveguide-gratings are very sensitive to the angle of the incident wave. Hence, the narrow-band filter suffers significant reduction in the peak reflectance, even if the incident optical beam is wide [3].