No description available.

No description available.

Thesis (Ph.D.) - University of St Andrews, June 2008.

Thesis (M.S.)--University of Michigan, 1958.

No description available.

Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: fiber amplifier; erbium; excited state absorption; rare earth fluorescence; neodymium. Includes bibliographical references (leaves 70-72).

Optical amplification and signal processing are of great importance to ensure reliable operation of fiber-optic networks. The capacity of optical networks are growing rapidly to deal with the ever-growing Internet traffic demand, which requires optical amplification and signal processing to have ultra-fast response, wide operation bandwidth, flexible operation spectral range and transparency to different modulation formats. In this regard, fiber optical parametric amplifiers (FOPAs), which rely on the efficient parametric process in highly nonlinear fibers, are promising to operate as amplifiers and signal processers in future high-capacity optical networks. This thesis focuses on the advanced schemes of optical amplification and signal processing based on FOPAs to cope with the developing optical networks. / New optical amplifiers are highly desirable for previously unused optical bands to increase aggregate optical communication bandwidth. Raman-assisted FOPAs are promising because they can provide higher gain efficiency than Raman amplifiers and more flexible operation spectral range than the conventional FOPAs. Gain saturation is an important property of parametric amplification, which may result in signal distortion during amplification but can be utilized for optical regeneration. In this thesis, gain saturation characteristics in a Raman-assisted FOPA are experimentally observed and theoretically analyzed through simulations. As compared to a conventional FOPA, gain saturation is deferred with enhanced saturated output power and the saturated gain spectrum is broadened with suppressed signal wavelength dependence in the Raman-assisted FOPA. The novel saturation behaviors are explained by the modification of the parametric pump power and nonlinear phase mismatch by the backward Raman amplification. Moreover, controlling saturation behaviors by tuning the Raman gain on the parametric pump are demonstrated. / Amplification performance of Raman-assisted FOPAs is further investigated, including single-channel amplification incorporating with coherent reception and multi-channel amplification for wavelength division multiplexing (WDM) systems. In the single-channel amplification, sufficient amplification performance for the QPSK signal has been successfully achieved in two Raman-assisted FOPAs with the same signal gain of 19 dB but different pump power combinations. In addition, the FOPA with a higher Raman pump is more advantageous due to the wider gain bandwidth and the deferred signal gain saturation. Nonlinear crosstalk is the major restriction of FOPAs for multi-channel amplification in WDM systems. We propose and demonstrate suppression of cross-gain modulation (XGM) crosstalk and four-wave mixing (FWM) crosstalk using a Raman-assisted FOPA. The performances are compared between FOPAs with and without the Raman pump under the condition of identical unsaturated gains. The reduction of XGM crosstalk utilizes the deferred gain saturation in the Raman-assisted FOPA which implies a larger range of input signal power for a constant gain. On the other hand, the suppression of FWM crosstalk is based on the unique signal power evolution which has a crescent slope along the fiber. Accordingly, the performance of multi-channel amplification has been improved in the Raman-assisted FOPA. / Polarization division multiplexing (PDM) in combination with phase-shift keying (PSK) signals is being increasingly employed to improve the spectral efficiency of optical networks. Gain-saturated FOPA is an attractive approach to reduce the nonlinear phase noise and improve the transmission performance by suppressing the amplitude noise of PSK signals. In this thesis, saturation characteristics of FOPA are investigated in terms of input signal polarizations. Our theoretical analysis and experimental results show that PDM signals exhibit nearly identical saturation behaviors when two orthogonal polarized pumps are applied. In addition, polarization-insensitive gain saturation can be achieved by optimizing the pump powers. We report the experimental demonstration on polarization-insensitive amplitude regeneration of 40-Gb/s DPSK signals and amplitude regeneration of 80-Gb/s PDM RZ-DPSK signals. / 光信號的放大和處理在確保光纖通信網絡的可靠運行中起著至關重要的作用。隨著因特網流量需求的不斷增長，光網絡的容量也在高速增長，這就要求光信號的放大和處理具有超快的響應速度，更大的工作帶寬，靈活可調的光譜範圍以及對不同調制格式的透明度。光纖參量放大器是一種基於高非線性光纖的高效率參量過程的多功能器件，非常適合用於未來高容量光網絡中的光信號放大和處理。本論文將致力於研究基於光纖參量放大器的先進技術以適用於快速發展的光通信網絡中光信號的放大和處理。 / 為了拓展總的光通信帶寬，適用於新的光學波段的新型光放大器是非常重要的。拉曼輔助光纖參量放大器具有高於拉曼放大器的增益效率，與傳統的光纖參量放大器相比更加靈活的工作光譜範圍，是一種優秀的新型光放大器。增益飽和是參量放大過程的一種重要特性，它既可能引進放大過程中的信號損傷，又可用於全光再生。本文通過實驗觀察和理論模擬研究了拉曼輔助光纖參量放大器的增益飽和特性。與傳統的光纖參量放大器相比，拉曼輔助光纖參量放大器需要更高的信號輸入功率以達到增益飽和，具有增強的飽和輸出功率。飽和條件下其增益光譜被展寬，而飽和特性與信號波長的相關性被減弱。通過模擬計算，我們得出這些新穎的飽和特性的物理解釋：反向的拉曼放大過程改變了參量泵浦功率和非線性相位失配在光纖中的分布。另外，通過調節參量泵浦的拉曼增益，我們還展示信號增益飽和特性的控制。 / 我們進一步研究了拉曼輔助光纖參量放大器在信號放大方面的性能，包括了單通道信號的放大和波分復用系統中多通道信號的放大。在單通道信號放大的研究中，我們研究了兩種具有不同泵浦功率組合的放大器，而這兩種放大器都提供19dB的增益。實驗中，我們采用相幹接收對放大後的四相相移鍵控信號進行分析，發現兩種放大器都具有令人滿意的放大效果。同時我們還發現其中具有高的拉曼泵浦功率的放大器更有優勢，因為它能夠提供更大的增益帶寬和更加延遲的信號增益飽和。非線性串擾是光纖參量放大器應用於波分復用系統中多波長信號放大的主要障礙。我們提出拉曼輔助光纖參量放大器可用於抑制多通道信號放大時的交叉增益調制串擾和四波混頻串擾。在我們的研究中，拉曼輔助光纖參量放大器在多通道放大方面的優越性能是通過與具有相同線性增益的傳統光纖參量放大器進行比較體現出來的。拉曼輔助光纖參量放大器的延遲增益飽和說明了在更大的信號輸入光功率範圍內不會引起參量泵浦的明顯減弱，因而可以用於抑制交叉增益調制串擾。另一方面，拉曼輔助光纖參量放大器使信號在光纖中具有獨特的功率演變過程，可用於降低四波混頻串擾。因此，我們利用拉曼輔助光纖參量放大器成功地提高了多通道放大的信號質量。 / 偏振復用技術與相移鍵控調制格式的結合越來越多地被用於提高光網絡的頻譜效率。光纖參量放大器的增益飽和是一種很有吸引力的抑制相移鍵控信號幅度噪聲的方法，可以有效地降低非線性相位噪聲從而提高傳輸性能。本文研究了不同信號偏振情況下光纖參量放大器的增益飽和特性。理論分析和實驗結果都顯示在采用正交偏振的參量泵浦時偏振復用信號具有相同的增益飽和特性。另外，偏振不敏感的增益飽和可以通過調節泵浦功率實現。我們成功展示了40-Gb/s非歸零差分相移鍵控信號的偏振不敏感幅度再生以及80-Gb/s偏振復用歸零差分相移鍵控信號的幅度再生。 / Guo, Xiaojie. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2014. / Includes bibliographical references. / Abstracts also in Chinese. / Title from PDF title page (viewed on 12, September, 2016). / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only.

Chan Wai-Leung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references. / Abstracts in English and Chinese. / ABSTRACT --- p.I / 摘要 --- p.III / Acknowledgements --- p.V / Table of Contents --- p.VII / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Different All-Optical Signal Processing Functions --- p.3 / Chapter 1.1.1 --- Periodic optical signal generation --- p.3 / Chapter 1.1.2 --- Optical clock recovery and clock synchronization --- p.4 / Chapter 1.1.3 --- Wavelength conversion and signal regeneration --- p.5 / Chapter 1.1.4 --- Optical multicasting --- p.6 / Chapter 1.1.5 --- All-optical time division multiplexing and demultiplexing --- p.6 / Chapter 1.2 --- SOA-MZI as the Prime Candidate --- p.7 / Chapter 1.3 --- Overview of the Thesis --- p.8 / References --- p.10 / Chapter 2 --- basic Properties of Semiconductor Optical Amplifier Based Mach-Zehnder Interferometer --- p.16 / Chapter 2.1 --- Semiconductor Optical Amplifier Based Mach-Zehnder Interferometer --- p.16 / Chapter 2.1.1 --- Characteristics of SOA-MZI --- p.17 / Chapter 2.2 --- Review on Different Reported Applications of SOA-MZI --- p.19 / Chapter 2.2.1 --- Format converter --- p.19 / Chapter 2.2.2 --- Mode-locked fiber ring laser --- p.20 / Chapter 2.2.3 --- OTDM ADD/DROP Multiplexer --- p.21 / Chapter 2.2.4 --- Optical Switch --- p.21 / References --- p.23 / Chapter 3 --- Self-Starting All-Optical Photonic Clock --- p.24 / Chapter 3.1 --- Introduction --- p.24 / Chapter 3.2 --- Principle of Photonic Clock Generation --- p.26 / Chapter 3.3 --- Basic Configuration --- p.27 / Chapter 3.3.1 --- Basic results --- p.28 / Chapter 3.3.2 --- Effects of state of polarization --- p.31 / Chapter 3.3.3 --- Effects of an isolator within the feedback loop --- p.34 / Chapter 3.3.4 --- Phase noise characteristics --- p.35 / Chapter 3.4 --- Multi-Loop Configuration --- p.36 / Chapter 3.4.1 --- Results examined in time domain --- p.38 / Chapter 3.4.2 --- Results examined in frequency domain --- p.38 / Chapter 3.4.3 --- More multi-loop results --- p.40 / Chapter 3.5 --- Other Proposed Scheme --- p.40 / Chapter 3.6 --- Summary --- p.43 / References --- p.44 / Chapter 4 --- All-Optical Clock Recovery --- p.46 / Chapter 4.1 --- Introduction --- p.46 / Chapter 4.2 --- Principle of All-Optical Clock Recovery --- p.47 / Chapter 4.3 --- Experiments Setup --- p.48 / Chapter 4.4 --- Clock Recovery Demonstration --- p.50 / Chapter 4.5 --- External Clock Synchronization Demonstration --- p.53 / Chapter 4.6 --- Summary --- p.55 / References --- p.56 / Chapter 5 --- Wavelength Conversion Optimization Using a Holding Beam --- p.57 / Chapter 5.1 --- Introduction --- p.57 / Chapter 5.2 --- Principle of Wavelength Conversion Under Injection of a Holding Beam --- p.58 / Chapter 5.3 --- Wavelength Conversion Using a Holding Beam --- p.62 / Chapter 5.4 --- Effect of a Holding Beam on Wavelength Conversion --- p.63 / Chapter 5.5 --- Optimizing the Effect of Holding Beam Assisted Wavelength Conversion --- p.67 / Chapter 5.6 --- Summary --- p.68 / References --- p.69 / Chapter 6 --- All-Optical Multicasting of Digital Signal with Format Conversion --- p.70 / Chapter 6.1 --- Introduction --- p.70 / Chapter 6.2 --- Principle of Switching-Wavelength Pulses Generation --- p.72 / Chapter 6.3 --- Principle of Multicasting Using SOA-MZI --- p.75 / Chapter 6.4 --- Experiment on Multicasting --- p.76 / Chapter 6.5 --- Performance of the Multicasting Scheme --- p.79 / Chapter 6.6 --- Summary --- p.84 / References --- p.85 / Chapter 7 --- Optical Demultiplexing for Time Division Multiplexed Data Source With Wavelength Conversion --- p.87 / Chapter 7.1 --- Introduction --- p.87 / Chapter 7.2 --- Principle of Optical Time Division Demultiplexing Using SOA-MZI --- p.90 / Chapter 7.3 --- Demonstration of Optical Time Division Demultiplexing --- p.91 / Chapter 7.4 --- Results and Discussions --- p.93 / Chapter 7.5 --- Summary --- p.96 / Chapter 8 --- Conclusion and Future Works --- p.100 / Chapter 8.1 --- Conclusions --- p.100 / Chapter 8.2 --- Future Works --- p.102 / Appendices --- p.A-1 / Appendix A. List of Publications --- p.A-1 / Appendix B. List of Figures --- p.A-2

Both gain transient and dynamic gain control devices were also designed and fabricated as photonic integrated circuits (PICs). Silicon-based PICs were able to perform dynamic gain tilt compensation by thermo-optic effect. Helium doped SOI rib waveguides were used for power monitoring and is potentially used as monolithic gain tilt compensation device with arrayed waveguide grating (AWG). / Dynamic gain tilt induced by wavelength dependent gain of EDFA leads to power penalty in wavelength division multiplexed systems. Using optical filter with known spectral response, it is possible to detect dynamic gain tilt and a per-band compensation scheme using electronic variable optical attenuators. This was implemented for dynamic gain tilt compensation (DGTC). / Dynamic provisioning of bandwidth and re-configurable optical networks can potentially allow efficient and cost effective deliveries of services based on the actual bandwidth requirement. Optical add/drop multiplexers (OADM) and optical cross-connects (OXC) will be used for such networks but the dynamic provisioning of optical channels may introduce optical power transients because of the slow gain dynamics of erbium doped fiber amplifiers. In this dissertation, the potential problems on using Erbium Doped Fiber Amplifiers (EDFA) in future reconfigurable optical networks are studied and possible solutions are assessed. In particular, the problems of gain transient and dynamic gain tilt were studied experimentally and theoretically. / In saturated EDFA channel add/drop can produce average power fluctuations, in timescales in the microsecond range. The thesis describes how gain transients can be minimized in gain clamped EDFA by optimizing erbium concentrations of EDF. Both simulations and experiments demonstrate that highly doped EDF minimize the transient in gain clamped EDFA. For unclamped EDFA, all-optical feedforward constant output power compensation has been successfully demonstrated using electronic variable optical attenuator (EVOA). / Chan Po Shan. / "August 2006." / Source: Dissertation Abstracts International, Volume: 68-03, Section: B, page: 1813. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

The main work of this thesis is to design the TE-polarized SOA structures for booster amplifier, and the polarization-independent SOA structures for preamplifier at receiver end. In the SOA structure, we add a lattice-matched ternary compound InGaAs as an extra quantum well in separate-confinement heterostructure (SCH) layer. The purpose is to result in the band-filling/shrinkage and lead to change the absorption coefficient. Therefore, the refractive index change will be increased, and the structure can work as a Mach-Zehnder interferometer under reverse bias. We also added an electron barrier InAlAs layer to reduce the carriers accumulation in the extra InGaAs QW. After the epitaxy of MOCVD, this designed structure was processed to be a ridge laser. From the measurements of ridge laser, the barrier InAlAs could not efficiently stop the carrier injection into the extra InGaAs QW. The other part of this thesis is to set up a digital signal apparatus to analyze the RHEED pattern on the screen of the chamber. We make a connection between CCD camera and PC utilizing the framegrabber in RHEED system, and develop the programs from LabVIEW and IMAQ to obtain the functions we need. Further, from the tests of grabing and analysis for RHEED pattern, the digital signal system on RHEED pattern has been successfully demonstrated.