Dynamics and Frequency Noise for Laser Diode Stabilization between Non-Radiative Recombination Rate and Optical Feedback

Laser diodes are crucial for the success of long-distance optical communication systems operating in the 1.2- to 1.6-μm range. The performance of these remarkable devices is significantly affected by optical feedback from external reflectors, which is determined by factors such as feedback strength, external cavity length, and injection current. Additionally, the rate of non-radiative recombination plays a crucial role in the performance of laser diodes, influencing key parameters such as carrier lifetime, threshold current, and turn-on time delay. In this study, we emphasize the important roles of non-radiative recombination rate and optical feedback in enhancing the dynamics and frequency noise of laser diodes. We categorize the dynamics of lasers based on bifurcation diagrams of photon numbers. Our findings indicate that a lower non-radiative recombination rate stabilizes the laser output and promotes periodic oscillation or continuous wave modes. In regions with strong optical feedback, decreasing the non-radiative recombination rate shifts the operation from chaotic to stable modes, aligning the frequency noise with the characteristics of solitary lasers. In chaotic regions, the frequency noise increases by over twelve orders of magnitude compared to the noise level of solitary lasers. Conversely, under weak optical feedback, an increase in the non-radiative recombination rate leads to a significant rise in low-frequency noise. By carefully engineering the non-radiative recombination rate and adjusting the strengths of optical feedback, we can effectively stabilize the performance of laser diodes and advance laser technology.