This dissertation combines aspects of lasers, nonlinear optics and interferometry to measure the linear optical properties involved in phase matched second harmonic generation, (SHG). A new measuring technique has been developed to rapidly analyze the phase matching performance of potential SHGs. The data taken is in the form of interferograms produced by the self referencing nonlinear Fizeau interferometer (NLF), and correctly predicts when phase matched SHG will occur in the sample wedge. Data extracted from the interferograms produced by the NLF, allows us to predict both phase matching temperatures for noncritically phase matchable crystals and crystal orientation for angle tuned crystals. Phase matching measurements can be made for both Type I and Type II configurations. Phase mismatch measurements were made at the fundamental wavelength of 1.32 (mu)m, for: calcite, lithium niobate, and gadolinium molybdate (GMO). Similar measurements were made at 1.06 (mu)m. for calcite. Phase matched SHG was demonstrated in calcite, lithium niobate and KTP, while phase matching by temperature tuning is ruled out for GMO.

Thesis (Ph.D.)--University of Melbourne, School of Physics, 2003. / Typescript (photocopy). Includes bibliographical references (leaves 121-132).

The work described in this dissertation can be divided into two parts. The first part is an investigation of the transient behavior and stability property of a phase conjugate resonator (PCR) below threshold. The second part is an experimental and theoretical study of the PCR's spatiotemporal dynamics above threshold. The time-dependent coupled wave equations for four-wave mixing (FWM) in a photorefractive crystal, with two distinct interaction regions caused by feedback from an ordinary mirror, was used to model the transient dynamics of a PCR below threshold. Analytical expressions of the steady state cavity's fields for the case of nondepleted pumps and an absorption free medium were derived and used to determine the self-oscillation conditions. The solutions, through simple frequency domain transformation techniques, were used to define the PCR's transfer function and analyse its stability. Taking into account pump depletion and medium absorption, the transient buildup and decay times of the cavity's fields as well as the specularly reflected and phase conjugate reflected intensities were numerically calculated as functions of a number of system parameters such as the coupling parameter and the pump and probe ratios. General trends were unveiled and discussed in view of the possible use of the PCR in image storage or processing architectures. Experimental results for the buildup and decay times confirmed qualitatively the predicted behavior. / Ph. D.

An optical image feedback system utilizing a cavity with a phase-conjugate mirror (PCM) has been studied. A new theory, based on operators, is developed to describe the steady-state output of the cavity. The use of operators allows one to describe the various optical operations and transformations needed in the optical implementation of iterative algorithms. The characteristics of the cavity are discussed using an expansion of the cavity fields in the cavity eigenfunctions. Several image processing applications using a PCM cavity are proposed and are studied using computer simulations. These theoretical studies indicate that a PC11 cavity can be useful in many applications. Optical phase conjugation was realized using a single crystal of photorefractive BaTi0₃ in a degenerated four-wave mixing geometry. The reflectivity gain from the PCM was optimized experimentally by the geometrical parameters and by the beamintensity ratios. The ability of the PCM to remove phase distortion as predicted theoretically, was demonstrated experimentally. The output of a PCM cavity can be substantially influenced by self-oscillations of the cavity above threshold. This was experimentally studied by observing the time evolution of the input. To avoid the influence of self-oscillation, the cavity must be operated below threshold. It is found that the cavity decay time constant diverges at and about threshold. This can be used as an indicator to show whether the cavity has crossed the threshold or to measure how close to threshold the cavity operates. To verify that a PCM cavity can be used in iterative image processing, an experiment was set up to implement an image restoration scheme based on the Gerchberg algorithm. It is shown that an optical implementation of the Gerchberg algorithm is feasible for objects made of few pixels. The experiment confirmed .that image iteration in a PCm cavity is possible. The limitations of the cavity and the technical difficulties are discussed. / Ph. D.

Lam Sio Kuan. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references (p. 111-116). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

For packet-switched metro networks, one of the key functional blocks is the transmission, extraction and update of in-band packet control information, which is commonly known as packet label swapping. The use of phase modulation to carry the control information can facilitate easy swapping process. By combining phase modulated label with intensity modulated optical packets in non-overlapping manners, we demonstrated that optical packet label swapping using differential phase-shift keyed labels could be achieved without any sacrifices in packet signal quality. / In packet-switched optical networks, packets are routed using IP-based distributed routing algorithms. Inconsistencies in routing information among routing nodes may result in routing loop formation in the network and may cause severe impact on the network performance. We proposed a novel packet routing loop mitigation scheme based on the principle of packet 'time-to-live' value countdown. This scheme enables loop mitigation to be performed asynchronously in optical domain, causing little packet processing delay. Two implementations were proposed. One was based on differential optical phase shift keying and the other was based on self-phase modulation in semiconductor optical amplifier. / The continuous increase in Internet-bound data traffic in recent years has placed higher requirement on network bandwidth and flexibility. In view of this, packet-switched metro networks and broadband passive optical access networks have emerged as the promising network solutions in the near future. The focus of this thesis is on the improvement of functionality and reliability as well as the reduction of system complexity in optical metro area and access networks with the use of optical phase modulation techniques. In access network, constant-intensity optical phase modulation formats were studied for their applications in wavelength-division-multiplexed passive optical networks with centralized light source. Using them as downstream modulation formats, the downstream optical carrier can be utilized to carry upstream intensity-modulated data. It can greatly simplify upstream transmission and facilitate network management. Experimental and numerical analyses shows promising upstream re-modulation performance with a simple optical network unit (ONU) configuration. / Hung Wai. / Adviser: Lian-Kuan Chen. / Source: Dissertation Abstracts International, Volume: 70-09, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 130-135). / 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.

by Tong Wai Yin Alex. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1996. / Includes bibliographical references (leaf 55). / by Tong Wai Yin Alex. / Acknowledgement / Biographical Sketch / Abstract / Table of contents / Chapter Chapter 1 --- Introduction --- p.1 / Chapter Chapter 2 --- Nonlinear Optics in dye-doped solid --- p.4 / Chapter 2.1 --- Nonlinear Optics --- p.4 / Chapter 2.2 --- Photophysics of dye molecules --- p.6 / Chapter 2.3 --- Nonlinear effect in dye-doped solid --- p.8 / Chapter Chapter 3 --- Sol-Gel Silica --- p.11 / Chapter 3.1 --- The formation of dye-doped sol-gel silica --- p.11 / Chapter 3.2 --- The physical properties --- p.15 / Chapter 3.3 --- The optical properties --- p.16 / Chapter Chapter 4 --- Saturation Absorption --- p.18 / Chapter 4.1 --- Saturation Absorption in Fluorescein 548 dye-doped solid --- p.18 / Chapter 4.2 --- Experimental Details --- p.19 / Chapter 4.3 --- Results and Discussion --- p.19 / Chapter 4.4 --- Conclusion --- p.30 / Chapter Chapter 5 --- Optical Phase Conjucation --- p.31 / Chapter 5.1 --- OPC Theory --- p.31 / Chapter 5.11 --- The Distortion Correction Theorem --- p.32 / Chapter 5.12 --- The Proof of the Distortion Theorem --- p.32 / Chapter 5.13 --- The generation of Phase Conjucate Waves --- p.34 / Chapter 5.2 --- Degenerate Four Wave Mixing --- p.35 / Chapter 5.21 --- Geometries of DFWM --- p.35 / Chapter 5.22 --- DFWM Theory --- p.37 / Chapter 5.23 --- DFWM in Absorbing Media --- p.40 / Chapter 5.3 --- Experimental Details --- p.44 / Chapter 5.4 --- Results and Discussion --- p.46 / Chapter 5.5 --- Conclusion --- p.53 / Chapter Chapter 6 --- Conclusion and Suggestions for future work --- p.54 / Reference

In the current transmission systems, the transmission capacity is still not enough. The information bandwidth of the optical fiber communication system is limited by the optical amplifier bandwidth, and more efficient use of the bandwidth is a very important issue. Therefore, the amplitude and phase shift keying (APSK) is one attractive method of multi-bit per symbol modulation scheme to improve the spectral efficiency, and it can effectively increase the transmission capacity. To improve the capacity and the spectral efficiency, the advanced modulation format is effective, and the coherent detection scheme is also effective. However, an optical phase-locked loop (PLL) to lock the local oscillator (LO) phase and the signal phase required for the homodyne detection is still difficult to realize and it makes the receiver circuit complicated. Using the digital coherent receiver, the optical carrier phase information can be recovered by means of the digital signal processing (DSP), and this scheme enables to eliminate the optical PLL circuit by the phase estimation algorithm through the DSP. The stored data can be offline processed by using the MATLAB program. This master thesis is focusing on studying the transmission performance of the APSK format using the DSP in the digital coherent receiver. 497km transmission experiment has been conducted. Subsequently, the stored data are offline processed by the algorithms of the DSP. Then, the APSK performances between back-to-back and 497km transmission are compared.

This thesis studies and mathematically models nonlinear interactions among channels of modern high bit rate (amplitude/) phase modulated optical systems. First, phase modulated analogue systems are studied and a differential receiving method is suggested with experimental validation. The main focus of the rest of the thesis is on digital advanced modulation format systems. Cross-talk due to fiber Kerr nonlinearity in two-format hybrid systems as well as 16-QAM systems is mathematically modelled and verified by simulation for different system parameters. A comparative study of differential receivers and coherent receivers is also given for hybrid systems. The model is based on mathematically proven assumptions and provides an intuitive analytical understanding of nonlinear cross-talk in such systems. / Graduate

Les réseaux et systèmes de télécommunications mondiaux fondent aujourd'hui leur confidentialité sur la cryptographie classique, qui repose sur des hypothèses mathématiques fragiles. La distribution quantique de clef (QKD) est aujourd'hui la seule façon connue pour distribuer des clefs avec une sécurité inconditionnelle. Ce travail de thèse contribue à combler de manière pluridisciplinaire et polyvalente le gap entre les limites physiques fondamentales et l'implémentation expérimentale, en termes de vitesse, fiabilité et robustesse. Dans un premier temps, nous avons donc proposé une implémentation du protocole BB84 utilisant les états de phase cohérents. Le récepteur homodyne a été conçu de manière à compenser les fluctuations de phase et de polarisation dans les interféromètres, ainsi que dans le reste du canal de propagation. Ensuite, nous avons mis en place un dispositif expérimental de système QKD à la longueur d'onde 1550 nm, avec une modulation QPSK fonctionnant avec un trajet et un sens de parcours uniques, dans une fibre optique mono-mode. Les deux schémas de détection: le comptage de photons (PC) et la détection homodyne équilibrée (BHD) ont été mis en œuvre. Enfin, nous avons effectué des comparaisons théoriques et expérimentales de ces deux récepteurs. Le récepteur BHD a été élaboré avec une décision à double seuil. La mise en œuvre d'un tel processus accepte des mesures non-conclusives, et réduit l'efficacité de génération des clés, mais reste encore bien meilleur que celle des PCs à 1550 nm. Nous avons également prouvé que ce système est robust sous la plupart des attaques potentielles.