| Summary: | 碩士 === 國立臺北科技大學 === 光電工程系研究所 === 98 === In this paper, we firstly studied the gain-switching distribution feedback (DFB) semiconductor laser with the external-injection and self-injection locking technologies to generate optical pulse. We use a radio frequency (RF) signal of 2.5 GHz and 15 dBm to modulate 1550 nm DFB laser to obtain the short optical pulse. Then external-injection by using a tunable continuous wave (CW) laser, and self-injection from fiber ring cavity and FBG were used to generate the optimize pulse train, respectively. Through optical spectrum analyzer and digital communication analyzer measurement, we discuss the injection-locking characteristics in frequency-domain and time-domain. In frequency-domain, the side-mode suppression ratio (SMSR) and line-width were including. However, in time-domain, the pulse-width, RMS jitter and pulse power parameters were obtained. In addition, we also detuned the injection ratio, wavelength, and temperature to observe the influence of parameter both in frequency-domain and time-domain. The optimize optical pulse with pulse-width of 45 ps, RMS jitter of 2 ps, pulse peak power of 3 mV, and SMSR greater than 40 dB are obtained.
Secondly, we employed external-injection or fiber ring self-injection locking scheme for DFB laser to form an optimum optical pulse train. Then the pulse train was feed into a MZM modulator driving by a 2.5 Gbit/s NRZ signal format. Thus we obtained a 2.5 Gbit/s RZ format optical pulse from the modulator output port. The modulated 2.5G RZ signal was then transmission through 10 Km and 30 Km single mode fiber. We compare the optical pulse transmission performances with two injection-locking schemes in our proposed system. At same time, we also detune the DFB diode temperature to observe system power penalty. Employing two injection-locking scheme and after transmission over 30 Km SMF, the power penalty within of 3.4 dB, and a tolerable temperature range of 3 ℃ were achieved.
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