Experimental Research on Dynamic Characteristics of Mutual Optical Injection Semiconductor Lasers with Long Delay

The nonlinear dynamics of optical injection semiconductor lasers have been widely studied and applied. Recently, mutual optical injection is a valuable method for exciting nonlinear dynamics due to its unique advantages, including non-photoelectric conversion, low phase noise, and high adjustability. However, the effects of operating conditions and injection parameters of mutual optical injection semiconductor lasers on nonlinear dynamics are still in the exploratory stage. In this paper, the nonlinear dynamics within mutual optical injection distributed feedback semiconductor lasers based on the fiber links with long delay have been experimentally studied. The experimental results indicate that when the frequency detuning is less than 10 GHz, the dynamic evolution in the mutual optical injection is similar to that in the external light injection. However, it is for the first time that the coexistence of multiple dynamics is observed when the frequency detuning exceeds 20 GHz. In addition, increasing the carrier number and disrupting polarization matching will increase the nonlinear threshold. When increasing the injection photon number through external light amplification, the semiconductor lasers will appear chaotic due to additional noise. These conclusions contribute to precise control of dynamic evolution. It offers the potential for generating frequency-modulated continuous-wave or multi-tone signal through all-optical means.