Thesis (M.S.)--California Polytechnic State University, 2009. / Mode of access: Internet. Title from PDF title page; viewed on Jan. 20, 2010. Major professor: Dr. Dennis Derickson. "Presented to the Electrical Engineering Department faculty of California Polytechnic State University, San Luis Obispo." "In partial fulfillment of the requirements for the degree [of] Master of Science in Electrical Engineering." "December, 2009." Includes bibliographical references (p. 111).

A new tuning scheme for linearly tunable high-Q filters is proposed. The tuning method is based on using the phase information for both frequency and Q factor tuning. There is no need to find out the relationship between a filter's passband magnitude and Q. A gm-C biquadratic filter is designed to demonstrate the proposed tuning circuitry. The project includes a phase locked loop (PLL) based frequency tuning loop, reference clock generator, and differential difference amplifier (DDA) for dealing with frequency and Q factor tuning loop and linearly tunable second order gm-C bandpass filter. Simulation results for a 10 MHz prototype filter using AMI 0.5μm process is presented. The chip testing results show that the automatic frequency tuning error is 2.5% for the 10 MHz case.

No description available.

No description available.

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 (M.S.)--California Polytechnic State University, 2008. / Mode of access: Internet. Title from PDF title page, viewed on March 26, 2009. Major professor: Dennis Derickson, Ph.D. "Presented to the Electrical Engineering Department Faculty of California Polytechnic State University, San Luis Obispo." "In partial fulfillment of the requirements for the Master of Science degree in Electrical Engineering." "December 2008." Includes bibliographical references (p. 93-94). Will also be available on microfiche.

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.

No / This paper presents a physically compact, frequency tunable antenna design for use in mobile terminals. The full operating bandwidth is between 1750 MHz and 2400 MHz with good impedance match in the entire tuning range to meet the coverage requirements of the DCS, PCS, UMTS and WLAN bands . The antenna bandwidth is is realized by loading the embedded resonant slot of a PIFA, with a varactor diode, with an equivalent capacitance range of 0.5 pF to 2.5 pF.

Yes / A frequency tuned antenna has been designed to meet the coverage requirements of the DCS, PCS, UMTS and WLAN bands. The antenna consists of a main patch, and a planar inverted L (PIL) slot. The radiator patch is fed, and shorted, using simple feed lines with broadband characteristics. The handset represents the finite ground plane, and a varactor diode is mounted across the middle of the slot for tuning purposes. Initial tuning was obtained by placing lumped capacitors, instead of the varactor, over the radiator. Good agreement is obtained between the predicted and measured input return loss, gain and radiation pattern over the tuned frequency range. / MSCRC

This research is for the implementation of non-intrusive measurement techniques in the study of high temperature pipe flow. A low pressure, laboratory scale hybrid rocket motor simulator was built to achieve high temperatures with various gases. A quartz test section was designed, built, and implemented into the existing test setup to accommodate the laser beam of the existing Tunable Diode Laser Absorption Spectrometer (TDLAS) system which was designed to observe water vapor. A super-heated water vapor injector was designed to obtain the desired water vapor concentrations. Flow characteristics were simultaneously recorded using the existing TDLAS system and the DAQ system for temperatures for later comparison. A numerical study using a commercial CFD package was used to predict the flow characteristics at certain locations for experimental comparison. Based on this study, it is concluded that the TDLAS can be used to make real time temperature measurements of heated internal gas flows.