Multicolor long-wavelength QWIPs based on double metal–dielectric–metal layers

A quantum well infrared photodetector (QWIP) using a longitudinally stacked bilayer metal–dielectric–metal structure (MDM) is proposed. By integrating three metasurface square patches with two quantum well active regions, three different resonant cavities can be formed with the metal substrate to achieve three-color detection. The finite element method is employed to calculate the electric field distribution, intersubband absorption and responsivity of the device. As per the findings, the E Z electric field components of all three cavities can be enhanced by more than five times in comparison to the initial value E 0 . The device exhibits absorption peaks at wavelengths of 6.5 µm, 7.4 µm, and 10.6 µm, respectively. Furthermore, the device’s intersubband absorptions are six times higher than those of the standard 45° device. High responsivity is obtained across all three wavelengths. Our study shows that the three resonant cavities remain unaffected by each other due to the spatial isolation and that the response wavelengths are independently tunable over a range of wavelengths. Our results offer an approach to multicolor infrared detection that offers design flexibility.