Broadband chaotic signal generation with a solitary microcavity laser

We have proposed and experimentally demonstrated a novel chaotic signal generator using a solitary deformed square microcavity laser. The carrier density in the microcavity laser exhibits periodic or chaotic oscillation due to the interaction between the cavity modes, as long as the frequency difference between the modes is comparable to the relaxation oscillation frequency of the laser. The oscillation of carrier density leads to the variation of the Fermi level and, consequently, the applied voltage. The electrical signal can then be extracted directly from the electrode of the microcavity laser without the need for optical-electrical conversion. The obtained chaotic signal has a standard bandwidth of 9.6 GHz, and physical random numbers can be generated from the temporal waveform with simple post-processing methods. The scheme demonstrated here requires simple hardware, making it a promising solution for chaotic signal generators in various applications.