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Over Bandwidth NRZ Modulation of TO-can Packaged Long-cavity Colorless Laser Diodes with Low Front-facet Reflectance for DWDM-PON Systems
No full text分波多工光網路系統(WDM-PON)因其諸多優點已被視為因應未來需求的最佳選擇，為了降低成本、提高應用的可能性，有許多為了分波多工光網路的光源被提出，例如單模雷射、反射式的被導體放大器、利用放大後的自發輻射光源(ASE)注入鎖模的、相互注入的費比布洛雷射等等。我們使用的長共振腔無色費比布洛雷射(long-cavity colorless laser diode)是一種降低端面反射率和增加共振腔長的費比布洛雷射，因此相較於一般費比布洛雷射具有寬頻譜的優點，相較於反射式的被導體放大器則具有較好的同調性。本篇論文首先討論不同的低端面反射率值對做為傳訊器的雷射特性的影響，在可調式雷射注入鎖模後長共振腔無色費比布洛雷射的傳輸表現，其直接調變速率為2.5 Gbit/s。當端面反射率從0.2%增加至1.2%，訊雜比(SNR)和ER可分別增加8.3%和8%，而在誤碼率(BER)為10-9情況下，接收功率分別為-26.4 dBm (0.2%)和-27.9dBm (1.2%)。除此之外，我們也嘗試使用長共振腔無色費比布洛雷射在高速調變的分波多工光網路系統中作為傳訊器，其調變速率為10Gbit/s，同時，我們也進一步討論注入功率大小對傳輸表現的影響。為了降低外來元件對頻寬的影響，我們將雷射接腳剪短、連接SMA接頭，在直接連接PRBS訊號產生器，其中並未再使用bias tee。當注入功率從-12dBm調整至-3 dBm時可有效抑制側模功率，將側模抑制比從39 dB提高至50 dB。在注入功率為-3 dBm的情況下，接收功率為-12.2 dBm時可達到BER為10-9。為了更仔細探討端面反射率與注入功率對雷射頻率響應的影響，依據雷射的速率方程式(rate equations)，我們使用MATLAB程式模擬不同緞面反射率及不同注入功率下的雷射頻響。在相同操作電流比例下(Ibias/Ith)，低端面反射率的雷射具有略佳的頻寬，而注入功率也有一定有效範圍。最後，為了改善長共振腔無色費比布洛雷射溫度無法被控制的問題，我們設計新的mount使其在操作上更容易被注入鎖模，以避免先前誤碼率量測時出現的floor問題。在WDM-PON系統中直接調變10Gbit/s長共振腔無色費比布洛雷射，其ER可達到6.95 dB、SNR可達到6.18 dB，而接收功率為-15.4 dBm下誤碼率為10-9。經過25公里色散位移光纖後，誤碼率10-9時有3.8 dB功率懲罰。In this thesis, the long-cavity colorless laser diodes with different front-facet reflectance are employed to perform the wavelength injection-locked on-off-keying data transmission. By changing front-facet reflectance from 0.2% to 1.2%, the received OOK data improves both signal-to-noise ratio (SNR) and extinction ratio (ER) by 8.0% to enhance the Q factor by 6.3%, which benefits bit-error-rate (BER) reduction by more than two orders of magnitude. As the injection-locking power is raised from -6 to -3 dBm, the receiving power sensitivity of the long-cavity colorless laser diode is improved from -27.9 to -29.2 dBm at BER of 10-9. However, the long-cavity colorless laser diode with a lower front-facet reflectance shows an opposite trend. The injection-locking induced enhancement is limited within a frequency region controlled by the injection power, which results from a large disparity between continuous-wave injection and stimulated emission inside the long-cavity colorless laser diode. Next, a 600-um long-cavity laser diode with 2% low front-facet reflectance is demonstrated as a colorless OC-192 transmitter for the future DWDM-PON, which is packed in a TO-56-can package of only 4-GHz frequency bandwidth but can be over-bandwidth modulated with 10-Gbit/s non-return-to-zero (NRZ) data-stream. The coherent injection-locking successfully suppresses its side-mode intensity and noise floor level, and improves its modulation throughput at higher frequencies. With increasing the coherent injection-locking power from -12 to -3 dBm, the side-mode suppression ratio significantly increases from 39 to 50 dB, which also suppresses the frequency chirp from -12 to -4 GHz within a temporal range of 150 ps. Such an over-bandwidth modulated laser diode still exhibits an on/off extinction ratio of 6.68 dB and a signal-to-noise ratio of 4.96 dB, which can provide a back-to-back receiving power via sensitivity of -12.2 dBm at BER of 10-9. Furthermore, the effect of different front-facet reflectance and injection power are analyzed theoretically based on rate equations. In free-running case, the long-cavity laser diode with a lower front-facet reflectance possesses not only a broader spectrum but a larger modulation bandwidth under a fixed bias current ratio (Ibias/ Ith) operation. Implementing an appropriate amount of injection power, the relaxation resonance frequency and the damping rate can be enhanced owing to the additional coupling of photon density to the phase of the injection -locked laser. In fact, the over-injected and unmodulated photons are unable to create more stimulated emission photons but being noise component in the cavity. By equipping the long-cavity laser diode with temperature control device, the long-cavity colorless laser diode transmitter demonstrates a better transmission performance in WDM-PON system with bit rate of 10 Gbit/s. At back-to-back transmission case, the receiving power sensitivity at BER of 10-9 is -15.4 dBm with ER of 6.95 dB and SNR of 6.18 dB. After 25-km DSF transmission, the receiving power sensitivity slightly degrades to -11.6 dBm at a requested BER of 10-9.口試委員會審定書 ii
誌謝 iii
中文摘要 iv
ABSTRACT v
CONTENTS vii
LIST OF FIGURES ix
LIST OF TABLES xii
Chapter 1 Introduction 1
1.1 Introduction 1
1.2 Motivation 2
Chapter 2 Coherent Injection-Locking of Long-Cavity Colorless Laser Diodes with Low Front-Facet Reflectance for DWDM-PON Transmission 5
2.1 Introduction 5
2.2 Experimental Setup 5
2.3 Results and Discussions 7
2.3.1 The effect of front-facet reflectance on power, noise and wavelength detuning characteristics of the long-cavity colorless laser diode under coherent injection-locking 7
2.3.2 The effect of front-facet reflectance on transmission performances of the long-cavity colorless laser diode transmitter under coherent injection-locking 13
2.4 Summary 19
Chapter 3 Beyond bandwidth NRZ modulation of a weak-resonant-cavity Fabry-Perot laser diode with TO-56-can package for DWDM-PON 21
3.1 Introduction 21
3.2 Experimental Setup 21
3.3 Results and Discussions 24
3.3.1 The effect of injection power on power, mode ,noise and chirp characteristic 24
3.4 Summary 32
Chapter 4 OC-192 NRZ direct modulation of TO-56 packed long-cavity colorless laser diode with 2% front-facet reflectance 34
4.1 Introduction 34
4.2 Experimental Setup 34
4.3 Modeling 36
4.3.1 Differential Analysis of the Rate Equations 36
4.4 Results and Discussions 42
4.4.1 The effect of injection-locking power on modulation bandwidth, transmission performance of the long-cavity colorless laser diode 42
4.5 Summary 46
Chapter 5 Conclusion 48
5.1 Conclusion 48
REFERENCE 5
Going Beyond Counting First Authors in Author Co-citation Analysis
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counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
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koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
[[alternative]]Community-Based Employment Service:Viewpoints from Employment Specialists and Supervisors
No full text[[abstract]]The purposes of this study were to understand the practical and administrative difficulties of community-based employment services. The method of Interview was used while conducting this research. The informants of this study came from seven institutes, which provided community-based employment services for person with disability. Ten employment specialists (ES) and seven of their supervisors (ESS) were interviewed .
This results of this study were as followed:
1.The work morale and the improvement of professional capability for ES, as well as the quality of their service are influenced by (1) ESS' responsibility and ability to supervise their ES, (2)Staffs' understanding and support of the employment service, (3) The ways of the employment service, (3) The in-service training in the institution, and (4) The support from the administrators.
2. The difficulties to process employment service include: (1) The clients can not really reach the really independent situation, so they need continual supports; (2) It is difficult to communicate with parents and employers; (3) The social support web is not well-connected for the clients and their families; (4) The work opportunities are limited; (5) The cooperation and concession among the institutions need to be facilitated; (6) It is not easy to integrate resources so the ES' professional role has to be enhanced and expanded.
3. The difficulties to really develop the roles of administrative systems include: (1) The ES and ESS do not realize the administrative regulations and procedures; (2) ES' heavy work loading result in stress; (3) A good welfare system for the ES does not existed; (4) There is no certified professional education of ES and ESS; (5) ES do not appropriately look for the assistance from other professionals.
The suggestions to improve the community-based employment service are: (1) To enrich staff's understanding for the community-based employment service; (2) To employ ESS with practical experiences; (3) To establish a professional support web; (4)To integrate resources in order to well-connected clients and their families' social support web; (5) To advocate the importance for person with disability to work in our community; (6) To provide certified training courses with academic credits; (7) To have flexible case loading.
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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