Random Bit Generation in VCSEL with Delayed Optoelectronic Feedback

This paper presents a method for generating random bits using a semiconductor laser with optoelectronic feedback, which induces chaotic dynamics. Numerical simulations of the system equations, incorporating the alpha factor and time delay, revealed that for τ > 2.5 ns, the system transitions to a chaotic regime, confirmed by a continuous intensity spectrum. For bit generation, the chaotic signal was sampled at 40 GHz, followed by 8-bit quantization and extraction of the 4 least significant bits. The resulting sequence of bits successfully passed all 15 NIST SP 800-22 tests, including frequency, entropy, and correlation assessments. The implemented scheme demonstrates a generation rate of up to 160 Gbit/s, highlighting its potential for high-performance security systems.