- 學位論文
增益開關半導體雷射注入鎖模技術產生光脈衝之研究
Optical pulse transmission performances based on Gain-Switched semiconductor laser and injection-locking technologies
摘要
在本論文中，我們主要探討利用增益開關半導體二極體，及外部注入與自回饋注入等技術，令被注入之DFB雷射二極體產生短脈衝光源。本論文第一部份，討論光脈衝之形成，我們運用一台射頻訊號(RF)產生器，以調變頻率為2.5 GHz及振幅為15 dBm之正弦信號來觸發1550 nm DFB半導體雷射二極體，使DFB雷射二極體產生增益開關機制之光脈衝；同時運用一台可調式連續光源做外部注入，及運用環型共振腔及布拉格光纖光柵所形成自回饋注入等方式對DFB雷射進行注入鎖模，以獲得最佳化之短脈衝光源。透過光頻譜分析儀與數位通訊分析儀之量測，探討光脈衝在頻域及時域上特性之變化及優缺點，包含分析頻域上之側模抑制比(SMSR)，3-dB線寬，以及分析時域上脈衝光之寬度、時間跳動(Jitter)、脈衝功率等參數。同時去改變不同的注入功率比、微調注入波長以及變化溫度等參數探討對光脈衝之穩定度。我們得到最佳化之光脈衝寬度約為45ps、時間跳動小於2 ps、脈衝功率大於3 mV、側模抑制比大於40 dB。 論文第二部份，我們將運用外部注入與環型共振腔自回饋注入兩種方式，注入至DFB雷射二極體所完成最佳化之脈衝光源後，再運用外部調變之方式，載送與光脈衝頻率相同之2.5 Gbit/s非歸零碼(NRZ)，調變出2.5 Gbit/s歸零碼之光脈衝(RZ Optical Pulse)。並且將RZ光脈衝信號傳送10公里和30公里單模光纖，觀測二種不同的注入方式所產生出最佳化之RZ光脈衝傳送在系統上之容忍值。同時去改變溫度之變化，加以討論最佳化RZ光脈衝傳輸在系統上受溫度變化之影響。兩種方注入方式之RZ信號經傳送30公里後，仍擁有3.4 dB容忍值，且對溫度變化之影響，約有3 ℃容忍範圍。
並列摘要
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.