Copper vapour laser (CVL) pumped dye lasers offer a source of high power, kilohertz repetition rate, tunable narrow-bandwidth radiation suitable for many spectroscopic applications in the visible and infra-red. Furthermore, the nonlinear frequency conversion of CVL-pumped dye laser radiation extends the wavelength range of these laser sources into the blue and ultra-violet. A series of experimental investigations have been undertaken to gain a physical understanding of the fundamental parameters necessary for the optimization of the CVL-pumping of dye lasers. Issues addressed include the influence of the CVL cavity design, the pump beam polarization and geometry, the dye oscillator cavity design, the choice of grating materials, and the dye flow rate. A model based on the rate equation analysis of the kinetic processes relevant to optical amplification in dye lasers has been developed, and the results have been used to design amplifiers with extraction efficiencies in excess of 45 %. As a result of the aforementioned investigations, three commercially available pulsed dye lasers have been successfully optimized for CVL-pumping for the first time. Once modified, these dye lasers have typically shown conversion efficiencies in excess of 20%, with frequency bandwidths as narrow as 800MHz, and beam qualities approaching the diffraction limit. The theory of second harmonic generation is reviewed, and a suite of corresponding computer models have been developed to form the basis for a coherent experimental investigation of UV generation using the CVL and CVL-pumped dye lasers. CVL SHG has been demonstrated in jS-barium borate (BBO) and lithium triborate (LBO), with SHG efficiencies in excess of 18% realized for the CVL 511nm line in BBO. For the first time, an experimental comparison of spherically and elliptically focused second harmonic generation has been undertaken. Optimized elliptical focusing is found to be up to 30% more efficient than using conventional spherical focusing in agreement with theoretical predictions. The superior divergence and transverse coherence of CVL-pumped dye lasers, in comparison to those of the CVL, is reflected in the SHG efficiencies achieved in BBO, LBO and lithium iodate. Conversion efficiencies approaching 40% have been demonstrated in lithium iodate, with harmonic conversion coefficients approaching 2400mW/W2 realized at low input powers. The Boyd and Kleinman theory of SHG with focused Gaussian beams is found to provide an excellent description of SHG with CVL-pumped dye laser radiation, and accurately predicts the optimum strength of focusing and harmonic conversion coefficient. For the first time, sum frequency mixing (SFM) of the CVL with a dye laser has been demonstrated, and found to provide a potentially efficient source for tunable UV radiation. Finally, the application of CVL-pumped dye lasers to resonant ionization mass spectrometry and tropospheric hydroxyl (OH) radical detection is discussed, and the spectroscopic potential of a frequency doubled CVL-pumped dye is demonstrated by recording the absorption spectrum of OH at 308nm.

Thesis (MS)--Montana State University--Bozeman, 2009. / Typescript. Chairperson, Graduate Committee: Wm. Randall Babbitt. Includes bibliographical references (leaves 67-70).

Previous studies of distributed feedback dye lasers (DFDL's) have identified that the linewidth of the device scales, to a first approximation, with the level of pumping employed. A more recent development is that the DFDL can be used to produce single ultrashort pulses. To produce such pulses the main requirement is that the laser is operated close to its threshold. An apparent contradiction exists here since, by lowering the pump power to achieve narrow linewidth operation, the near threshold region must be avoided since pulsing operation acts to increase the linewidth (to at least the Fourier transform of the pulse duration). This thesis further investigates the mechanisms which contribute to the temporal and linewidth properties of the laser. It is identified that by judicious choice of operating conditions a regime exists where the DFDL may be operated with a linewidth approaching that of the transform limit for the nanosecond pulse durations involved. After introducing the different types of distributed feedback lasers the thesis first reviews previously understood DFDL behaviour. Different DFDL geometries are considered with a view to their particular temporal and linewidth properties. A strategy for the development of a narrow linewidth DFDL is presented. The experimental laser system is described detailing the operation and characteristics of the frequency doubled Q switched Nd:YAG pump laser and the two different DFDL geometries. A high resolution computer aided interferometry (CAIN) system is described which provided single shot linewidth measurements. This system was used extensively in the experiments reported. DFDL linewidth is seen to depend on the thermo-optical properties of the dye's host solvent and as such a full characterization of commonly used solvents is presented. The temporal behaviour of the laser is considered theoretically with the aid of a coupled rate equation model which describes the interplay between the population inversion and the cavity photon flux. The model is used to predict short (picosecond) and smooth (nanosecond) pulse operation of the laser. Finally, a description of and the results obtained from various experimental investigations into the DFDL are presented. Temporal analysis, using a streak camera, revealed that, as expected, under certain circumstances multiple pulsing of picosecond duration could occur. Different conditions however, lead to narrow linewidth (~100 MHz) operation. A description of the two operating regimes is presented and these are related to the particular parameters involved e.g. the grating length or the level of pumping employed.

The work in this thesis is concerned with the development of tunable, femtosecond laser systems, exhibiting low pump threshold powers. The main motive for this work was the development of a low threshold, self-modelocked Ti:Al2O3 laser in order to replace the conventional large-frame argon-ion pump laser with a more compact and efficient all-solid-state alternative. Results are also presented for an all-solid-state, self-modelocked Cr:LiSAF laser, however most of this work is concerned with self-modelocked Ti:Al2O3 laser systems. In chapter 2, the operation of a regeneratively-initiated, and a hard-aperture self- modelocked Ti:Al2O3 laser, pumped by an argon-ion laser, is discussed. Continuous- wave oscillation thresholds as low as 160mW have been demonstrated, along with self-modelocked threshold powers as low as 500mW. The measurement and suppression of phase noise on modelocked lasers is discussed in chapter 3. This is followed by a comparison of the phase noise characteristics of the regeneratively-initiated, and hard-aperture self-modelocked Ti:Al2O3 lasers. The use of a synchronously-operating, high resolution electron-optical streak camera in the evaluation of timing jitter is also presented. In chapter 4, the construction and self-modelocked operation of an all-solid-state Ti:Al2O3 laser is described. The all-solid-state alternative to the conventional argon-ion pump laser was a continuous-wave, intracavity-frequency doubled, diode-laser pumped Nd:YLF ring laser. At a total diode-laser pump power of 10W, this minilaser was capable of producing a single frequency output of ~1W, at 523.5nm in a TEM00 beam. The remainder of this thesis looks at the operation of a self-modelocked Ti:Al2O3 laser generating ultrashort pulses at wavelengths as long as 1053nm. The motive for this work was the development of an all-solid-state, self- modelocked Ti:Al2O3 laser operating at 1053nm, for use as a master oscillator in a Nd:glass power chain.

The work presented in this thesis describes the operation, characterisation and optimisation of a colliding-pulse modelocked (CPM) dye laser. A method of pulse analysis has been developed which is capable of determining the shape and chirp of the output pulses to a first approximation. It involves an iterative pulse-fitting to intensity autocorrelation, interferometric autocorrelation and spectral measurements. The use of a four-prism sequence for intracavity dispersion compensation in a CPM dye laser resulted in pulse durations of 40-50fs. However, operating the laser close to the instability regime so as to obtain strong focusing in the absorber dye jet enabled pulse durations as short as 19fs to be obtained. A detailed empirical study of the dispersion- compensated laser, together with a theoretical and experimental chirp analysis, indicated the presence of strong phase shaping arising from a net positive self-phase modulation, which was attributed to the optical Kerr effect occurring in the absorber dye solvent. Various modes of operation were observed, including unidirectional lasing and a higher- order solitonlike regime. The results of pulse-fitting were found to yield strong evidence for pulse asymmetry, the pulse profiles corresponding closely to an asymmetric sech2 pulse function with a longer leading edge. A computer simulation of the CPM dye laser provided a comprehensive understanding of the underlying pulse shaping dynamics of this system, elucidating fully the experimental behaviours observed, as well as providing a clear strategy for further optimisation of the laser. In particular, optimal performance was found to depend on strong amplitude and strong phase shaping, minimal spectral filtering, the control of higher-order dispersion and the provision of extracavity dispersion compensation. An experimental study of Gires-Tournois interferometers (GTI's) for intracavity cubic phase compensation identified the key requirements for cubic phase control in the CPM dye laser, while highlighting the limitations of utilising conventional GTI structures. A subsequent theoretical analysis enabled a more suitable strategy to be devised. It involved optimising the cavity optics and using a prism system with variable prism spacing, alone or in tandem with specially tailored GTI structures. Implementation of these findings resulted in pulse durations of around 30-40fs and the elimination of pulse asymmetry, which was attributed to a residual positive cubic phase. However, the appearance of a distinctive modulation in the wings of the pulse provided strong evidence that the pulse durations from the CPM dye laser had become limited by the next higher-order dispersion term; quartic phase. To demonstrate the direct relevance of this work to the more recently developed solid- state laser systems, an alternative all-solid-state femtosecond laser has been described. Based around a Ti:sapphire gain medium, the design of this laser incorporates the essential optimising principles and techniques developed for the CPM dye laser. The proposed system utilises a low-loss, broadband semiconductor saturable absorber mirror to initiate self-modelocking and a hybrid prism-chirped-mirror scheme for broadband intracavity and extracavity quintic-phase-limited dispersion compensation. When fully optimised, it is predicted that this laser should yield pulse durations as short as 5fs.

This thesis describes the design and development of a frequency doubled, continuous wave dye laser and its application to a study of the high Rydberg states of Rubidium. The laser uses the dye rhodamine 6G as the active medium and is optically pumped with an argon ion laser. Frequency doubling is by an ADA (ammonium dihydrogen arsenate) or ADP (ammonium dihydrogen phosphate) crystal located within the laser cavity. Continuous output powers in the ultra-violet in excess of 30 mW and tunable over the wavelength range 285-315 nm have been produced. The linewidth can be chosen to be 0.02 nm broadband system) or 0.002 nm (narrowband system) depending on the frequency selecting elements used. In order to keep insertion losses small the crystals have optical faces cut at Brewster's angle, and in order to increase generation efficiency the intracavity radiation field is focused into the crystal. Such an arrangement introduces the aberrations of coma and astigmatism which must be compensated by suitable cavity design. A variety of cavity and crystal configurations have been analysed for aberrations, and a novel arrangement for the simultaneous elimination of coma and astigmatism developed. Several practical frequency doubled dye lasers have been investigated. In particular the performances of ADA and ADP as the frequency doubling crystals are compared and contrasted. ADA has the advantage that it can be non-critically phase matched at these wavelengths and this results in a higher generation efficiency and a better UV beam quality than encountered with ADP. However, since it can only be temperature tuned, the tuning range (292-302 nm for temperature range 20-80°C) is more limited than that for ADP (285-315 nm) which can also be angled tuned. For both types of crystal, thermal phase mismatching is identified as the process limiting generation efficiency. Evidence is also presented that thermal focusing ultimately limits the UV output power by upsetting cavity stability. A computer model of intracavity frequency doubling has been developed. Thermal phase mismatching effects in the crystal as well as excited state absorption in the dye are included. This model is used to investigate the influence of cavity losses and crystal absorption on generation efficiency. Optimization of conversion efficiency by correct choice of crystal parameters is considered. Two systems have been developed to allow continuous scanning over an extended frequency range. One allows the broadband laser (0.02 nm) to be continuously tuned over 3 nm, the other allows the narrowband laser (0.002 nm) to be continuously tuned over 2 nm. The operation of a single frequency version of the laser and its stabilization on an external reference cavity is also described. The excitation of high Rydberg states in Rubidium using the frequency doubled laser is described. The states are detected by a space-charge limited ionization detector. The principal series of Rb up to a principal quantum number of n = 74 has been detected. A novel triode arrangement of electrodes in the space charge detector has enabled a small electric field to be applied to the rubidium vapour. The consequent Stark mixing of n2S, n2P and n2S states has allowed the n2S and n2D states to be excited from the 52S ground state. New term values of the n2S and n2D series are reported.

Orientadores: Marcio D'Olne Campos, Navin B. Patel / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-07-14T07:31:36Z (GMT). No. of bitstreams: 1 Carvalho_MauroMonteiroGarciade_M.pdf: 1282225 bytes, checksum: 4628e58c5c6df97ab49ae3f1f3e93883 (MD5) Previous issue date: 1977 / Resumo: Não informado / Abstract: Not informed / Mestrado / Física / Mestre em Física

Orientador: Navin B. Patel / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-07-15T15:52:32Z (GMT). No. of bitstreams: 1 Sacilotti_MarcoAntonio_M.pdf: 952260 bytes, checksum: f582ea8e835fd293747a901876bc6ff9 (MD5) Previous issue date: 1976 / Resumo: A existência de pouquíssimos dados experimentais sobre recombinações radiativas em laser de heteroestrutura dupla de semicondutor com a variação da temperatura nos levou a empreender este trabalho. Os lasers modernos de heteroestrutura dupla (HD), que apresentam densidade de corrente. Limiar (Jth) pequena, comparado com os lasers de homoestrutura e heteroestrutura simples (HS), não tem sido estudados o suficiente de maneira que existem poucos dados experimentais de perdas (a) e densidade de corrente limiar a baixas temperaturas. A observação destes e outros dados experimentais como: tempo de vida médio do elétron (Ts) e eficiência quântica externa (h) é de grande interesse para cálculos teóricos que possam vir a explicar o comportamento das recombinações radiativas nos lasers de semicondutor. Neste trabalho apresentamos um comportamento de Jth versus temperatura não muito comum e valores de Jth nunca antes observados para laser de HD a baixas temperaturas (80A/cm2 a 10K). A curva Jth x T apresenta-se decrescendo exponencialmente a baixas temperaturas, contrario ao que se observa comumente para lasers de homojunção, heteroestrutura simples e os primeiros lasers de HD que foram fabricados (1970a.d). Comumente se observa saturação de Jth a baixas temperaturas (menor que 50 Kelvin). Vários tipos de experiências complementares foram executadas na tentativa de explicar o comportamento de Jth x T. Estas experiências nos levaram ao cálculo de Ts, h e a dos lasers em várias temperaturas. As conclusões a que chegamos são: a) O mecanismo de recombinação radiativa é banda a banda. pelo menos para temperaturas acima de 80K, b) As perdas internas dependem fortemente da temperatura, c) A eficiência quântica interna diferencial é constante e aproximadamente igual a 1 para temperaturas de 10 a 300K e d) A saturação de Jth a baixas temperaturas para certos tipos de lasers, depende do comprimento de difusão do portador minoritário na região ativa. A parte inicial deste trabalho apresenta algumas características e alguns aspectos do desenvolvimento do laser de semicondutor. (*) Os resultados deste trabalho foram aceitos para apresentação na: V IEEE - Conferência Internacional de Laser de Semicondutor - Japão - setembro de 1976 / Abstract: There is a lack of experimental data about radiative recombination mechanisms in double heterostructure (DH) semiconductor lasers with variation of temperature. The modern DH lasers which show low threshold current densities compared with earlier lasers (1970a,d), have not been studied sufficiently and hence there is little experimental data about loss (a) and threshold current density (Jth) at low temperatures. The observation of these and other experimental data like: electron lifetime (Ts) and quantum efficiency (h) have great importance in theoretical calculations. This work shows a Jth x T relationship not very common and, at low temperature, a Jth value never observed before (80 A/cm2 at 10K) for DH lasers. The threshold current density continues to decrease exponentially to the lowest temperature studied (10 K), contrary to the observed in SH, homojunction and earlier DH lasers. The common behaviour is the saturation of Jth at low temperatures. Several types of complementary experiments were done to explain the Jth x T behaviour. These experiments gave us values of Ts, h and a for our lasers. The conclusions are: a) The radiative recombination mechanism is band to band at least for temperatures above 80K degrees. b)The internal loss depends strongly on temperature. c) The differential internal quantum efficiency is constant and approximately equal to 1 for all temperatures between 10 to 300K degrees and d)The Jth saturation at low temperatures depends on the diffusion length of minority carriers in active region, and the width of the latter. In the initial part of this work we present a resume of GaAs lasers development / Mestrado / Física / Mestre em Física

Orientador: Navin B. Patel / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-07-16T07:56:54Z (GMT). No. of bitstreams: 1 Prince_FranciscoCarlosde_M.pdf: 1038865 bytes, checksum: d772b6815f6efdc55a459bafcbbd3a02 (MD5) Previous issue date: 1977 / Resumo: Não informado / Abstract: Not informed. / Mestrado / Física / Mestre em Física

Orientador: Rogerio Cezar de Cerqueira Leite / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-07-18T03:23:41Z (GMT). No. of bitstreams: 1 Grossman_Benjamin_M.pdf: 1295320 bytes, checksum: ed2ab0ede504c36820bd58c46874fd2b (MD5) Previous issue date: 1973 / Resumo: Não informado / Abstract: Not informed. / Mestrado / Física / Mestre em Física