Mid-wavelength infrared resonant cavity enhanced photodiodes for infrared spectroscopic sensing of chemicals and other narrow-band optical signals

Metasurface Photodetectors

“…The resonant cavity enhances the responsivity at the resonant wavelength by incorporating the multiple pass detection scheme. Compared with the bulk photodetector, RCE-PD has the advantage of higher responsivity at the resonance wavelength, lower dark current, higher response speed, wider tunability, and narrow spectral response [36]. The optional reflectors of Fabry-Pérot resonant cavity include distributed Bragg reflector (DBR), high contrast grating reflector (HCG-R), photonic crystal slab reflector (PCS-R), and hybrid grating reflector [37].…”

“…Craig et al demonstrated that, by placing 96 nm of InAs 0.91 Sb 0.09 at the antinode of AlAs 0.08 Sb 0.92 /GaSb DBR based-Fabry-Pérot resonant cavity (Figure 7e), a peak spectral efficiency of 70% was achieved at 3.72 µm [38]. With the narrow bandwidth of 44 nm and the wide block region, the DBR based RCE-PD is suitable for detection of narrow gas absorption features [36]. Compared to DBR, PCS-R and HCG-R make easy fabrication and a highly reflective dielectric mirror achievable.…”