High-efficiency shallow-etched grating on GaAs membranes for quantum photonic applications

We have designed and fabricated a shallow-etched grating on gallium arsenide nanomembranes for efficient chip-to-fiber coupling in quantum photonic integrated circuits. Experimental results show that the grating provides a fiber-coupling efficiency of >60%, a greatly suppressed back reflection of <1% for the designed wavelength of 930 nm, and a 3-dB bandwidth of >43 nm. Highly efficient single-photon collection from embedded indium arsenide quantum dots to an optical fiber was realized with the designed grating, showing an average six-fold increase in the photon count compared to commonly used circular gratings, offering an efficient interface for on-chip quantum information processing.