The overall objective of the proposed project is to demonstrate the superior performance of metasurface-coupled avalanche photodiodes (M-APDs) over incumbent APDs without metasurfaces. The M-APDs represent a new strategy to achieve high-performance APDs and would allow a precise and reliably characterization of optical quantum states via homodyne detection. To achieve this objective, we will in Phase I demonstrate the high absorption (>90%) of 1550 nm light within a 100 nm-thick InGaAs layer on a low index substrate in a typical APD structure by coupling an appropriately designed metasurface. We will in Phase II fabricate the design optimized in Phase I and demonstrate M-APD operation with about two orders-of-magnitude reduction in dark current as compared to a state-of-the-art APD. Phase I objective and approach We propose a 12-month Phase I program to demonstrate that with a suitable metasurface, a 100 nm thick InGaAs layer can absorb the same amount of 1550 nm light as a micron-thick conventional InGaAs layer, which is the key to achieving M-APDs. We will use a synergetic modeling method that combines accurate finite-element simulations of metasurfaces, realistic Monte-Carlo simulations of carrier scattering, impact ionization and diffusion, and efficient mesoscopic device modeling to design suitable metasurfaces. We will take advantage of our extensive experience in infrared device fabrication and characterization to attain the designed metasurfaces and analyze their beneficial effect on optical absorption. Commercial applications and other benefits A successful demonstration of M-APDs with high quantum efficiency, large bandwidth, and low noise would have an immediate impact to the field of quantum information. The M-APDs can be used to achieve high-fidelity optical homodyne tomography. Our approach also represents a new strategy of improving APDs performance and will undoubtedly inspire new designs of M-APDs and boost their applications in quantum processing and 3-D laser ranging LIDAR.
