Ultranarrow band and high-quantum-efficiency photodetector with waveguide-grating structure and inclined top mirror

A new type of one-mirror inclined waveguide-grating photodetector, which combines a waveguide-grating filter and an inclined top mirror is proposed. Greatly improved spectral response is achieved by the integration of waveguide-grating into classical thin-film homogeneous layers. Comparison between the grating filter and Fabry–Perot filter demonstrates that this structure has two advantages over other photodetector devices. First, the inclined mirror can decouple the quantum efficiency from response speed and spectral response linewidth. Second, comparing the traditional photodetector with Fabry–Perot filter, this type of photodetector with the same materials requires significantly fewer layers while maintaining the same linewidth response, high peak efficiency and remarkably low sideband reflectivity. Thus, this type of photodetector device represents basic new optical features with a significant potential for practical applications.

► We model a new type of photodetector, which combines a waveguide-grating filter and an inclined top mirror.
► There are fewer dielectric pairs required for high reflectivity, which results in a somewhat simpler structure.
► The spectral width of the response is much narrower, because the use of grating filters.
► By integrating the traditional grating structure into the photodetector design, a more compact photoelectronic device with narrow linewidth is realized.