189 / 2024-07-01 16:04:53

Chaotical microcavity semiconductor lasers and applications

microcavity lasers, chaotic semiconductor lasers,,random bit generation

Chaotic Semiconductor lasers have attracted great attention for applications in physical random bit generation, secure communication, and chaotic detection, etc. Semiconductor lasers with external perturbations, such as optical injection, optical feedback, or optoelectronic feedback, are used to realize chaotical operation. But chaotic output of optical feedback chaotic lasers usually has weak time-delay periodicity, which reduces the random and security of the chaotic output. Here, we report chaotic semiconductor microlasers based on internal mode interaction by designing circular-side square microlasers. In the circular-side square microcavity, mode field distributions of the 0^th and 1^st transverse modes can be in-phase and anti-phase in half a region of the cavity, respectively. The corresponding enhancement and cancellation of mode beating intensities cause strong carrier oscillation at mode beating frequency and result in internal mode interaction similar as under external modulation. Based on carefully designed structure parameters, we fabricated circular-side square microlaser and experimentally observed successive route from periodic-one, periodic-three states to chaos by adjusting mode interval with injection current. Chaotic microcavity laser was verified due to internal mode interaction as the mode frequency interval approaching laser relaxation frequency. Furthermore, an enhanced chaotic bandwidth of 33.9 GHz was realized due to photon-photon resonance effect by designing a tri-mode chaotical microcavity laser, and 500 Gb/s random bit generation was verified with randomness statistics test. In addition, physical random bits were generated by directly extracting the chaotic microwave signal from the P-electrode of a chaotical microlaser.