Chaotic secure optical communication technology provides inherent high security through physical-layer encryption while maintaining compatibility with existing fiber-optic networks in terms of components, link architectures, and potential for high transmission rates, garnering substantial research interest. However, the practical implementation of chaotic secure communication faces two primary limitations: current chaotic communication rates lag behind modern fiber-optic systems, which have achieved transmission rates up to 200 Gbit/s, and most demonstrated systems utilize optical feedback semiconductor lasers with discrete components as chaos sources, presenting stability and mass production cost challenges. Therefore, enhancing chaotic carrier light bandwidth and achieving device integration are crucial requirements for improving these systems: the former determines transmission performance, while the latter addresses stability and cost issues in discrete components. Developing a broadband chaotic semiconductor laser with integrated structure as a chaos source is essential for advancing chaotic secure communication technologies. Building upon previous research, this study investigates the generation of bandwidth-enhanced laser chaos using integrated three-section distributed reflector (DR) lasers with optical drive, providing an optimal carrier light source for chaotic secure optical communication technology.

We adopted the research methodology combining simulation (based on the VPIcomponentMaker simulation software) with experimentation. First, by adjusting the injection intensity in simulations, we verified that the integrated three-section DR laser under chaos optical driving possesses the capability to generate wide-bandwidth laser chaos. Second, through adjustments of the bias current, we investigated the effects of the phase section and distributed Bragg reflector (DBR) section on chaos bandwidth. Then, we commissioned an external organization to fabricate the three-section DR laser and conducted experimental exploration of the three-section DR laser with optical drive by adjusting the injection intensity.

Simulation results demonstrate that under external chaos optical driving, the photon-photon resonance (PPR) effect in the three-section DR laser enhances the high-frequency spectral components of the chaotic RF spectrum, generating bandwidth-enhanced chaotic carrier light (Fig. 2). The research reveals that PPR resonance peaks emerge even under weak optical injection. As injection intensity increases, the low-frequency energy of the RF spectrum interacts synergistically with the PPR peaks, effectively promoting bandwidth enhancement of the laser chaos (Fig. 3). Additionally, adjusting the bias currents in the phase section and DBR section enables control of the PPR resonance peaks, allowing simultaneous regulation of chaos bandwidth. Both PPR frequency and intensity influence chaos bandwidth: PPR frequency governs the evolutionary trend of bandwidth variation, while PPR intensity determines the magnitude of these variations (Fig. 4). Experimental research demonstrates that the integrated DR laser with chaos optical drive generated laser chaos with a bandwidth of 31.38 GHz via the PPR effect, substantially exceeding the chaos bandwidth of the drive source (Fig. 6). The higher injection intensity required for maximum bandwidth in experiments compared to simulations primarily results from practical device losses and optical path losses. Despite this discrepancy, the experimental results regarding injection intensity’s influence on bandwidth closely align with simulation findings: increasing injection intensity initially enhances chaos bandwidth significantly, followed by saturation and eventual reduction. The bandwidth enhancement mechanisms in both cases derive from the PPR effect (Fig. 7).

This paper achieves chaos bandwidth enhancement in three-section DR lasers through chaos optical drive methods, validated in both simulations and experiments. The results demonstrate that this integrated laser exhibits PPR effects with optical injection, where the frequency and intensity of PPR peaks jointly determine the bandwidth enhancement. Simulation results reveal that under external chaos optical driving, the PPR effect in the three-section DR laser can enhance high-frequency spectral components of the laser chaos, generating bandwidth-enhanced chaos. Adjusting the bias currents in the phase section and DBR section enables precise control over the dynamics of laser chaos. Experimental results demonstrate that the three-section DR laser with chaos optical drive generates laser chaos with the bandwidth of 31.38 GHz, significantly exceeding the bandwidth of drive chaos. In experiments, the influence of the injection intensity variations on chaos bandwidth is highly consistent with simulation results, thereby confirming the scientific validity of the simulation research in this paper. This advancement is expected to provide a high-efficiency and broadband chaos source with multi-parameter tunability, simplifying system complexity while enhancing the performance and transmission rates of chaotic secure communication systems. The device holds significant importance for achieving co-driven open-loop broadband synchronization in future chaotic secure communication applications.