計畫名稱：多波長光孤子與同形光於石墨烯飽和吸收體鎖模光纖雷射之研究(II)
執行起迄：2015/08/01~2017/07/31
總核定金額：805,000元
中文摘要：現今通訊資料量與日倍增，對頻寬的需求更甚以往，光纖通訊網路之技術亦需隨之提升。而波長分工多工系統（WDM）能將光纖頻寬進行最有效率的應用，為光通訊網路中大幅提昇資訊流量的重要技術。日前WDM系統中所採用之光源大多是單獨存在之連續波輸出雷射二極體，需配置驅動電流源與溫度控制裝置等，以致所需成本大幅提高，整體體積增加。是以具有多波長且高能量脈衝雷射輸出光源為現今研究重點。在利用石墨烯飽和吸收體之被動鎖模技術中，有別於以往行進波直接穿透石墨烯之架構，我們已成功建置側磨光纖消散場與石墨烯飽和吸收體間交互作用之被動鎖模光纖雷射，以摻鉺光纖作為雷射增益介質，具有非線性吸收效應之石墨烯飽和吸收體為脈衝壓縮機制，因消散波耦合方式具有較高之破壞承受度（higher damage threshold），能達成較高功率之鎖模光纖雷射輸出。我們同時發現在提高泵激電流時，會導致多個光孤子產生於共振空中，每個光孤子能量變小形成諧波鎖模（harmonic mode locking），很難達成具高能量之光孤子型態脈衝雷射輸出。是以此次二年期研究計畫將延續目前之研究方向，於環形共振腔內置入光纖元件，改變腔內鎖模條件，預期建立多波長（multi-wavelength）且具高能量同形光（similariton laser）之鎖模光纖雷射輸出。第一年採用色散補償光纖改變腔內色散值，配合腔內非線性效應以得高能量同形光鎖模光纖雷射輸出，並分析輸出雷射特性與腔內色散值之關連性。第二年計畫於共振腔內置入Fabry-Perot濾波器達成多波長同形光鎖模雷射輸出，使其具有多波長輸出特性。
英文摘要：To support the increasing bandwidth demands of applications, further advances in optical fiber networks are needed. A key attribute of an optical fiber is its large accessible spectral bandwidth. One way to exploit this huge bandwidth is wavelength-division multiplexing (WDM). Current transmitted light-sources of WDM networks rely on banks of individual fixed continuous-wave laser diodes. Each laser diode requires current sources, temperature control and thermal management, and these lead to a higher cost and larger space requirements. Therefore, a multi-wavelength pulse laser with high energy output is considered. A passively mode-locked erbium-doped fiber laser based on graphene-deposited side-polished fiber at fundamental soliton-like operation has been demonstrated in our previous studies. There are mainly two ways of interaction between the saturable absorbers (SAs) and the signal light, direction type and evanescent field coupling, and the latter has the higher damage threshold. It is the reason that the evanescent field interaction is adopted in our study through a side-polished fiber. We also found that higher pumping currents result in multiple solitons (harmonic mode locking) in the cavity, which limits its pulse energy. To obtain the higher pulse energy, more advanced mode locking technique is required. Thus, this two-year proposal is to study multi-wavelength soliton and similariton in graphene-based mode-locked fiber lasers. The first-year work is to study the relationship between the pulse-laser propagation and the group velocity dispersion (GVD) of the ring cavity. The GVD could be controlled by employing a dispersion compensation fiber (DCF) with normal dispersion inside the cavity. The second-year study is to produce a multi-wavelength soliton and similariton by placing a Fabry-Perot filter inside the ring cavity which was built in the first year.