| Summary: | 碩士 === 元智大學 === 光電工程學系 === 105 === Nonlinear dynamics of semiconductor laser subject to dual feedback composed of both optical feedback (OF) and optoelectronic feedback (OEF) are investigated numerically and experimentally. When adjusting four controllable parameters of OEF delay time, OEF feedback strength, OF delay time, and OF feedback strength, more complex dynamics are obtained compared to those observed in individual OF and OEF system. Moreover, noise reduction of the regular pulses caused by the mixing of delay loop frequencies in dual feedback scheme is realized by applying an additional OF delay loop to the already-generated regular pulsing states from OEF scheme. To explore the quality of the generated regular pulses, the measurements of main frequency to the noise suppression ratio, spectral linewidth, and the single-side band (SSB) phase noise in frequency domain are examined. For the stabilized pulses generated, the main frequency to noise suppression ratio is increased from 48.9 dB to 70.6 dB, and the spectral linewidth of the main frequency is decreased from 3.25 kHz to 1.45 kHz. Furthermore, the irregular nonlinear behaviors generated from pure OEF system, such as quasi-periodic and chaotic pulsing states, are also transformed into regular pulsing states when further applying an OF loop to the semiconductor laser under carefully tuning the operational conditions.
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