Passive Chaos Bandwidth Enhancement Under Dual-Optical Feedback with Hybrid III–V/Si DFB Laser

The chaotic dynamics of a DFB laser are studied experimentally under a combination of short and long feedbacks. Chaos bandwidth enhancement is demonstrated using a hybrid III-V/Si DFB laser with a large relaxation oscillation frequency (ROF) of 14 GHz. The impact of short feedback on the ROF is studied and an increase of 2 GHz is observed. Under long feedback, the route to chaos of the device and its dependence on the short feedback dynamics are studied. The short feedback allows tuning the chaotic dynamics obtained under long feedback, and the increase of the ROF translates into an enhancement of the chaos bandwidth to above 16 GHz. This configuration can allow generation of wideband chaos using a single laser source in a photonic integrated circuit.