The development of newer technology is aimed at low cost health care with directed therapy. In this effort we have coupled two technologies microfluidics and optics to detect the malaria infection. We have designed and built a compact diagnosis platform for malaria. Very small quantity (order of micro liter) of blood was used as it is analyzed in microfluidic chip. Hemozoin crystal, a byproduct of malaria pigment produced third harmonic signal and our system was very sensitive to count the number of particles as they pass through the focus of microscope. The signal from infected blood show well-defined variation from its control. The study demonstrates rapid and sensitive detection of malaria. The strength of higher harmonic microscopy was also applied to study the structure of two proteins elastin and collagen in scarred vocal folds. Healthy and scarred rat vocal fold one month and two month post injury were examined at various regions. The results correlate with the infiltration of collagen at scarred tissue. From the results elasticity of tissue can be deduced from collagen content in the tissue. / Le développement de la nouvelle technologie vise à faible coût des soins de santé avec un traitement dirigé. Dans cet effort, nous avons couplé deux technologies microfluidiques et optiques pour détecter l'infection du paludisme. Nous avons conçu et construit une plate-forme de diagnostic compact pour le paludisme. Très petite quantité (pour des micro litre) de sang a été utilisé comme il est analysé dans la puce microfluidique. Hémozoïne cristal, un sous-produit de pigment malarique produite troisième signal harmonique et notre système est très sensible à compter le nombre de particules lors de leur passage à travers le point du microscope. Le signal de spectacle du sang infecté bien définis variation de son contrôle. L'étude démontre détection rapide et sensible du paludisme. La force de la microscopie harmonique supérieur a également été appliquée pour étudier la structure de deux protéines d'élastine et de collagène dans cicatrices cordes vocales. Saine et marquée rat cordes vocales un mois et deux mois après la blessure ont été examinés dans diverses régions. Les résultats en corrélation avec l'infiltration de collagène au niveau du tissu cicatriciel. À partir des résultats de l'élasticité du tissu peut être déduite de la teneur en collagène dans le tissu.

Tm3+ ions provide amplification in a wide variety of wavelength bands,including 480 nm, 810 nm, 1480 nm, 1900 nm, and 2300 nm. This thesis presentsthe characteristics of lasers fabricated with Tm:ZBLAN fibre as the gain medium.First, a single-wavelength linear cavity fibre laser at 810 nm is presented. Dual-wavelength lasing and bistable behaviour are demonstrated in single cavity lasers,while dual-wavelength lasing, bistable behaviour and wavelength switching are demonstrated in cascaded cavity lasers. Second, single wavelengths fibre lasers at 1480 nm in linear and ring cavities are presented. A maximum power of 340 mW at 1476 nm was obtained. Dual-wavelength lasing at 1476 nm and 1487 nm is shown in cascaded cavity lasers. Finally, using bi-directional pumping in a cascaded cavity, dual-wavelengthlasing at 1487 nm and 1487.6 nm, with a record narrow spacing of 0.6 nm, isachieved. / Le gain des ions de Tm3+ peut être utilisé dans un variété de bandes de longueurs d'ondes, incluant entre autres 480 nm, 810 nm, 1480 nm, 1900 nm et2300 nm. Ce mémoire présente les caractéristiques de lasers fabriqués avec des fibres de Tm:ZBLAN comme médium de gain. Premièrement, un laser à fibre à longueur d'onde simple à 810 nm, fabriquéavec une cavité linéaire est présenté. Une oscillation à longueurs d'ondes doubleset une opération bistable sont démontrées dans des lasers à cavités simples, puisune oscillation à longueurs d'ondes doubles, une opération bistable et une interversionde longueur d'onde sont démontrées dans des lasers à cavités en cascade. Ensuite, des lasers à fibre à longueurs d'ondes simples à 1480 nm, dans descavités linéaires et annulaires sont présentés. Un maximum de 340 mW à 1476 nma été obtenu. Des oscillations à 1476 nm et 1487 nm, obtenues avec des lasers àcavités en cascade, sont montrés.Finalement, un laser à 1487 nm et 1487,6 nm, avec l'aide d'une cavité en cascadepompée bi-directionnellement, est démontré, atteignant un écart record de0,6 nm.v

In this thesis, the analysis of mode locking process is formulated in terms of an eigenequation for the pulse envelope. The solutions of the eigenequation are found to be an infinite, denumerable set of supermodes, consisting of Hermite polynomials modulated by a Guassian envelope. The kinetics of pulse evolution from spontaneous noise is discussed in close analogy with the quantum statistical description. With the understanding of mode locked pulses, a new method to time tailor short pulses is presented. The method consists of the realization of a recursive filter by means of a suitable combination of high quality mirrors of different reflectivities. An algorithm to design a recursive filter for transforming a given pulse into a desired pulse is presented. As an example, a three mirror filter is designed to tailor a Guassian pulse to a pulse required for efficient laser induced controlled thermonuclear fusion.

Temporal characteristics of compressed femtosecond KrF pulses are measured with the help of a single-shot phase-sensitive autocorrelator for the UV. The performance of a prism compressor and the influence of higher order phase dispersion on the ultimate pulse width of compressed pulses is investigated. Self-phase modulation of high intensity femtosecond KrF pulses in MgF$\sb2$ is reported. The nonlinear refractive index n$\sb2$ (7.4 $\times$ 10$\sp{-16}$ $\pm$ 1.5 $\times$ 10$\sp{-16}$ cm$\sp2$/W) of MgF$\sb2$ is derived from the recorded broadened spectra. Implications of self-phase modulation in solids for compression of femtosecond KrF pulses are discussed.

The optical properties of metallic nanoshell systems are investigated using the Finite Difference Time Domain (FDTD) method. The method provides a convenient and systematic approach for calculating several physical properties of nanostructures, including the optical absorption and scattering cross sections as well as the local electromagnetic fields and induced charge densities near and on the surfaces of the nanoparticles. The method is applied to single uniform nanoshells as well as nanoshells with surface defects and structural distortions. The results show that, while defects can significantly affect local electric field enhancements, far field results such as extinction spectra can be remarkably insensitive to defects and distortions. Calculations are also presented for both homodimers and heterodimers. The results show that retardation effects must be taken into account for an accurate description of realistic size nanoparticle dimers. The optical properties of the nanoshell dimer are found to be strongly polarization dependent. Maximal coupling between the nanoshells in a dimer occurs when the electric field of the incident pulse is aligned parallel to the dimer axis. The wavelengths of the peaks in the extinction cross section of the dimer are shown to vary by more than 100 nm depending on the incident electric field polarization. The calculations show that electric field enhancements in the dimer junctions depend strongly on dimer separation. The maximum field enhancements occur in the dimer junction and at the expense of a reduced electric field enhancement in other regions of space. We investigate the usefulness of nanoshell dimers as substrates for surface enhanced Raman spectroscopy (SERS) by integrating the fourth power of the electric field enhancements around the surfaces of the nanoparticles as a function of dimer separation and wavelength. The SERS efficiency is shown to depend strongly on dimer separation but much weaker than the fourth power of the maximum electric field enhancement at a particular point. The SERS efficiency is also found to depend strongly on the wavelength of the incident light. Maximum SERS efficiency occurs for resonant excitation of the dimer plasmons. Specific implementation details as well as issues of numerical convergence are also discussed.

Photonic crystals are materials having a periodicity in their refractive index. This results in the inhibition of select frequencies of light from propagating within the crystal causing the formation of a gap in the photonic band structure. Analogous to semiconductors, the presence of a photonic band gap makes these materials tremendously promising for a new revolution in the technology industry. Their periodic nature make them ideal for two-dimensional lithographic fabrication. However self assembly methods with colloids offer the most promising route to fabricating three-dimensional structures, so as to affect the confinement of light in all directions. The work presented in this thesis strives to advance the understanding of colloidal crystals to ultimately facilitate the construction of real, working, commercial devices. We probe the optical properties of such colloidal crystals and describe techniques to engineer them into novel structures, such as crystals of hollow spherical shells, to enhance the performance of the photonic band gap. We examine novel architectures like colloidal photonic superlattices to generate propagation modes within the band gap and show that such structures can be fabricated to have uses as filters and optical resonators. We investigate incorporating colloidal crystal structures into organic light-emitting devices to improve device performance by spatially modifying the light output. Finally, as it is critical to fabricate high quality devices approaching the accuracy obtained by lithography, we conduct a systematic and quantitative study of the nature of defects in these colloidal crystals and correlate structural defects during fabrication to altered optical properties.

Optical transmission studies of three-dimensionally ordered photonic crystals of close-packed spherical shells are presented. These samples are fabricated using a double-template method, which allows for extensive control over shell thickness. The transmission spectra exhibit an optical stop band, whose spectral position and width depend on the thickness of the shell and on the overlap between adjacent spheres, in a manner consistent with numerical simulations. These parameters can be controlled over a wide range, thus permitting systematic studies of the optical properties, and providing a valuable method for engineering the characteristics of the optical stop band in colloidal photonic media.

A detailed investigation of tunable, high power excimer lasers, particularly of the electron-beam pumped XeF(C $\to$ A) laser, is presented. A numerical model is described which simulates the performance of such lasers. The output energy and temporal profile of an injection controlled XeF(C $\to$ A) excimer laser were successfully predicted for a wide range of experimental conditions. The XeF(C $\to$ A) excimer laser was demonstrated as a wideband tunable source of radiation capable of accessing a wavelength range from 455 to 530 nm. A high energy output of 1.2 J per pulse at a repetition rate of 1 Hz was accomplished by the use of a transverse gas flow cell. Injection controlled operation provided a narrow laser linewidth of 0.001 nm and three times diffraction limited spatial beam quality. Stimulated Raman scattering of the XeF(C $\to$ A) laser in hydrogen and liquid nitrogen was used to generate continuously tunable radiation between 525 and 650 nm with pulse energies exceeding 100 mJ. An energy conversion efficiency of 38% and a peak power of 35 MW were achieved. The XeF(C $\to$ A) excimer transition was characterized as a new gain medium for ultrashort pulse amplification. A gain bandwidth of 60 nm, as measured with 100 ps pulses, and a saturation energy density of 50 mJ/cm$\sp2$ for 250 fs pulses constitute a 20-fold improvement over other short pulse excimer laser systems. An ultrahigh power, short pulse amplifier system was designed and built, based on the gain measurements. An unstable resonator, particularly adapted to low gain conditions and high temporal purity was developed for the XeF(C $\to$ A) excimer amplifier. A maximum output energy of 275 mJ was obtained for amplified 250 fs pulses, resulting in terawatt peak power. A spatial beam quality of 2.4 times the diffraction limit was measured, which makes it possible to achieve an intensity of larger than 1 $\cdot$ 10$\sp{19}$ W/cm$\sp2$ in a focused beam. Therefore, the XeF(C $\to$ A) excimer laser amplifier can be used in an exciting new field of studies involving the interaction of ultrahigh intensity light with matter.

This paper presents a quantum cascade (QC) laser having an active region designed for both pump radiation emission and third order nonlinear emission. This design produces third harmonic generation from an InGaAs/AlInAs QC laser based on a three-well diagonal transition active region with an integrated third-order nonlinear oscillator. This design ensures efficient coupling of pump photon energy hv to the intersubband transitions of the nonlinear element and maximal overlap of interacting waveguide modes in the nonlinear active region. The problem of pump absorption is solved since the pump is generated in the nonlinear medium.

Metamaterials, artificially engineered structures with negative average relative permittivity and permeability, provide a route to creating potential devices with exciting electromagnetic properties that cannot be obtained with natural materials. One particularly interesting metamaterial device, is a planar metamaterial waveguide structure (MWS) that has potentially exciting applications. In this thesis, the properties and potential applications of metamaterial waveguide structures are explored. In particular, we examine the properties of metamaterial waveguides when the limitations arise from fabrication techniques and physical principles are taken into account. First, we study the basic properties of dispersion curves of an idealized (without loss and dispersion) metamaterial waveguide structure. We show that there are a rich variety of modes, such as the bound modes, the surface polariton modes, and the complex leaky modes, that are supported in MWS and have entirely different properties than the modes of a conventional waveguide structure. These novel modes provide more control over the electromagnetic fields and consequently lead to potential applications ranging from waveguide miniaturization to the slowing down of the light. Next, we study the effects of dispersion and loss, which are the inherent features of metamaterials, on the properties of MWS. We numerically show that the characteristic modes of the MWS are significantly changed particularly near the slow-light-modes when the intrinsic loss is introduced into the system. In particular we show that the stopped-light-modes disappear even in the presence of an arbitrarily small amount of loss. Moreover, we find several novel properties such as a splitting of complex leaky modes in a lossy MWS. / Thesis (Master, Physics, Engineering Physics and Astronomy) -- Queen's University, 2008-10-31 14:47:47.054