Controlling the Synchronization of Quantum Cascade Lasers with Negative Optoelectronic Feedback by Direct Current Modulation

In this study, I presented the synchronization of quantum cascade semiconductor lasers with optoelectronic negative feedback under the effect of direct current modulation. I investigated the synchronization quality by using the rate equations model. In both open-loop system and closed-loop system, the direct current modulation in transmitter laser and receiver laser has significant effects on the correlation coefficient. In both cases, we can use the direct current modulation to minimize the effect of mismatch in delay times on the synchronization quality. Also, the effect of modulation frequency in lasers has been analyzed. The correlation coefficient has a high value with increasing the modulation frequency in both lasers. Furthermore, the present results indicate that the correlation coefficient tends to high values at the negative value of the difference in the modulation frequency between the lasers in comparison with the positive value of the difference. The correlation coefficient has different behaviors when the delay time in transmitter laser is larger than the delay time in receiver laser or vice versa.