Spatiotemporal chaos based on a multimode laser for parallel physical random number generation

Physical random number generators (RNGs) based on laser chaos are widely used for secure communication and cryptography. Currently, frequency division multiplexing schemes have been developed to improve the rate of random bit generation. However, spatially multiplexed lasers for parallel RNGs remain a great challenge due to the limited number of independent transverse modes. Here, we propose a spatiotemporal chaotic laser array based on a single degenerate cavity for spatially parallel RNGs. By introducing transverse-mode competition to break the continuous spatiotemporal translation symmetry, we demonstrate the spontaneous spatiotemporal chaos in a single degenerate cavity laser. Then, a 4×4 independent chaotic laser array, with all cross-correlation coefficients below 0.05, is experimentally implemented by dividing the output transverse optical field using a two-dimensional amplitude mask with an array of apertures. Finally, we achieve 16 spatially parallel RNGs with offline postprocessing, yielding a total rate of 3.2 Mbps. Our work provides a new avenue for realizing parallel RNGs through multimode lasers.