Optical micro-ring resonator as an enabler for flat chaos generation

Chaotic lasers have been extensively studied for myriad applications. Yet, for typical chaotic devices, the power spectra are usually uneven with severe energy deficit at low frequencies, which poses a significant hurdle for realizing their practical applications. Here, we present a simple method to enhance chaotic low-frequency energy by injecting original chaos signal into a micro-ring resonator. The effects of detuning between the resonance frequency and chaotic frequency on the ratio of energy distribution in low-frequency bands are investigated. Our experimental results show that when the frequency detuning is 0 GHz, flat chaos with a bandwidth of 8.3 GHz can be obtained, and the energy ratios of the low-frequency bands concentrate at approximately 11%. Furthermore, we demonstrate that the significant enhancement of low-frequency energy is caused by the mode competition. The proposed scheme provides an attractive solution for flat chaos generation and shows great potential for chaos-related applications.