| Summary: | 碩士 === 國立交通大學 === 照明與能源光電研究所 === 105 === Optical heterodyne is a common way to generate radio frequency (RF) signal by optical source. In our research, the monolithic two-section distributed feedback (DFB) laser with a distributed Bragg reflector (DBR) structure can generate a tunable RF signal by the interaction between each laser cavity. Due to the advantages of optical feedback effect on laser performance, especially the linewidth, we demonstrated a feedback controlling system to investigate the spectral characteristics of RF signal under different feedback level. Eventually, the linewidth reduced to almost half of intrinsic signal with the max controllable feedback intensity, and a narrow linewidth RF signal was detected when the both sections of our monolithic device were influenced by optical feedback. The dynamic behavior of RF signals under different feedback level was investigated. To analyze the multi-mode signal, we constructed a convolution spectrum which could be used to fit the lineshape measured by delayed self-homodyne technique. Besides, the linewidth of RF signal was changed by different current configuration and exhibited narrower near the injection locking region.
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