Dynamical characteristics of semiconductor laser under both optical and optoelectronic feedback

Nonlinear dynamics of semiconductor lasers under individually optoelectronic feedback (OEF) and optical feedback (OF) is attracted much attention in these two decades. In this paper, nonlinear dynamics of single-mode distributed feedback (DFB) semiconductor laser subject to dual feedback composed of both optical feedback and optoelectronic feedback are investigated experimentally. The dynamical states shown in individual system are observed, quasi-periodic (QP) oscillation and pulsation, regular pulsation (RP), chaotic oscillation (CO) and pulsation (CP). To explore the microwave signals generated by quasi-periodic states in the dual feedback system, we also measure the suppression ratio of unwanted frequency side peak and RF spectral linewidth in frequency domain. On the other hand, the corresponding time series are also considered and discussed by calculating the amplitude variation of regular pulses and pulse widths. Moreover, a side peak suppression ratio of about 56 dB is achieved when applying the hybrid feedback scheme. The amplitude variation ratio of regular pulses is optimized to 0.008 and the pulse-width is approximately 0.12 ns which is smaller than those coefficient when applying individual OF and OEF system. The improved percentage of averaged amplitude variation in regular pulses of around 60 percent is also obtained. Furthermore, the complexity of chaotic waveforms generated by hybrid feedback system are discussed and calculated.