Guided-mode resonance based multicolor germanium infrared photodetector

A compact low-cost multicolor germanium (Ge) infrared photodetector is designed by utilizing the guided-mode resonance condition of a one-dimensional grating with adiabatically tuned (or so-called chirped) in-plane periodicity. It is shown numerically that the resonance phenomenon is accompanied by a spectral splitting, as every wavevector component is matched with different instantaneous local in-plane periods. In result, the proposed photodetector enables multi-wavelength photon absorption up to 61% efficiency and an ideal responsivity up to 0.63 A/W over a 70 nm bandwidth, while maintaining a very small active region of 0.413 μm
²
. The reported results provide a very valuable insight into highly miniaturized ultra-compact multicolor photodetection schemes.