This paper presents design and fabrication of ring cavity semiconductor lasers with simple fabrication processes and good potential for integration. A 1.55-£gm symmetric quantum well InGaAsP epi-layer wafer is used to fabricate the lasers. The fabrication processes involve a bi-level deep etching to reduce the bending losses. Two geometric types of ring cavity semiconductor lasers have been investigated. For the type 1 ring cavity in the form of race tracks, two different designs are presented. One has a single ring resonator (SRR) design and the other has a coupled double ring resonators (DRR) design. The resonator of the type 2 ring cavity is formed between a cleaved facet and a loop mirror. Both a single ring resonator (SRR) design and a double ring resonator (DRR) design are presented for this type of cavity also. The maximum saturation output light powers of 0.479 and 0.409 mW are observed in room temperature L-I measurements for type 1 and type 2 ring cavity semiconductor lasers respectively. The spontaneous emission spectra of the type 1 ring cavity semiconductor lasers show a red-shift phenomenon under increasing drive currents. The type 1 ring cavity semiconductor lasers with ring resonators of 100 and 200 £gm radii have also been found to exhibit an interesting wavelength clamping phenomenon of the output light.

This thesis describes the development and testing of two apparatuses; a vibrating wire viscometer to measure the viscosity of fluids over a wide range of temperature and pressure; and a microwave cavity resonator to measure dew points, gas phase densities, and liquid drop out volumes. Viscosity and density of downhole fluids are very important properties as their values can determine the economic viability of a petroleum reservoir. A vibrating wire viscometer has been developed with an electrically insulating tensioning mechanism. It has been used with two wires, of diameters (0.05 and 0.150) mm, to measure the viscosity of methylbenzene and two reference fluids with viscosities of (10 and 100) mPa·s at T = 298 K and p = 0.1 MPa, at temperatures in the range (298 to 373) K and pressures up to 40 MPa, where the viscosity covers the range (0.3 to 100) mPa·s, with a standard uncertainty < 0.6 %. The results differ from literature values by < ±1 %. The results demonstrate that increasing the wire diameter increases the upper operating viscosity range of the vibrating wire viscometer, a result anticipated from the working equations. For the microwave cavity resonator, the method is based on the measurements of the resonance frequency of the lowest order inductive-capacitance mode. The apparatus is capable of operating at temperatures up to 473 K and pressures below 20 MPa. This instrument has been used to measure the dew pressures of {0.4026CH4 + 0.5974C3H8} at a temperature range from 315 K up to the cricondentherm ˜ 340 K. The measured dew pressures differ by less than 0.5 % from values obtained by interpolation of those reported in the literature, which were determined from measurements with experimental techniques that have quite different potential sources of systematic error than the radio-frequency resonator used here. Dew pressures estimated from both NIST 14 and the Peng-Robinson equation of state lie within < ±1 % of the present results at temperature between (315 and 337) K while predictions obtained from the Soave-Redlich-Kwong cubic equation of state deviate from our results by 0.4 % at T = 315 K and these differences increase smoothly with increasing temperature to be -2.4 % at T = 337 K. Densities derived from dielectric permittivity measurements in the gas phase lie within < 0.6 % of the values calculated from the Soave-Redlich-Kwong cubic equation of state and about 1 % from values obtained with the Harvey and Prausnitz correlation based on a mixture reduced density. The calculations with Kiselev and Ely parametric crossover equation of state (based on Patel-Teja EOS) gave deviations < 0.7 %. Liquid volume fractions, in the 2-phase region, were measured from (0.5 to 7) cm3 in a total volume of about 50 cm3 at different isochors. The measured liquid volume fractions differ from values obtained with the Soave-Redlich-Kwong cubic equation of state by between 0 and 3 % at T < 326 K and about 8 % on approach to the critical region. The large deviations observed in the critical region were anticipated because of the known poor performance of the cubic equations of state with regard to the calculation of the liquid density in the vicinity of the critical temperature.

This paper presents design and fabrication of ring cavity semiconductor lasers and optical filters with simple fabrication process. A 1.55

In this thesis, we use InP based multiple quantum well epi-wafer with modulation doping in the active layer to design the semiconductor optical amplifier and ring laser for the optical communication at 1.55£gm wavelength. We also finish the mask design and fabrication of theses two devices. Besides, we have established an optical measurement system, including the L-I measurement, the optical spectrum measurement and the far field measurement, to test the device parameters. In the device process, we use the new method, called the Multi-Step Undercutting, to precisely control the undercut in the wet etching process. With this technique, we can get a smooth and vertical sidewall for our devices. For the semiconductor optical amplifier, we design two different types, one is the Fabry-Perot Amplifier and the other is the Traveling Wave Amplifier. We use the Multi-Step Undercutting process in the fabrication of these two devices. The main parameters for semiconductor optical amplifier are the change of the output power versus the input current, the spontaneous emission spectrum and the photocurrent spectrum. For the ring laser, we combine the concept of Loop Mirror and Asymmetric Mach-Zehnder Interferometer to obtain the laser with good side mode suppression for a single wavelength light source.

In this thesis, we focus on the investigation of semiconductor optical amplifier and ring laser. We use InP based multiple quantum well epi-wafer with modulation doping in the active layer to design the semiconductor optical amplifier and ring laser for the optical communication at 1.55£gm wavelength. We combine the concept of Loop Mirror and Asymmetric Mach-Zehnder Interferometer to obtain the laser with good side mode suppression for a single wavelength light source. For the semiconductor optical amplifier, we design two different types, one is the Fabry-Perot Amplifier and the other is the Traveling Wave Amplifier. Furthermore, We use the Multi-Step Undercutting process in the fabrication of these two devices. We have established an optical measurement system, including the L-I measurement, the optical spectrum measurement and the far field measurement, to test the device parameters. After annealing, these devices with two different serial number exhibited the contact resistances of 9£[ and 16£[, respectively. Under CW operation, these FPA exhibited the threshold current of 62mA and 70mA at 20¢J, respectively. The stimulated emission wavelength was at 1531nm and 1522nm, respectively.

Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2014-11-10T10:46:11Z No. of bitstreams: 0 / Made available in DSpace on 2014-11-10T10:46:11Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado em Tecnologia Nuclear) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Yes / Potential demodulating ability in biological tissue exposed to Radio Frequency (RF) signals intrinsically requires an unsymmetrical diode-like nonlinear response in tissue samples. This may be investigated by observing possible generation of the second harmonic in a cavity resonator designed to have fundamental and second harmonic resonant frequencies with collocated antinodes. Such a response would be of interest as being a mechanism that could enable demodulation of information-carrying waveforms having modulating frequencies in ranges that could interfere with cellular processes. Previous work has developed an experimental system to test for such responses: the present work reports an electric circuit model devised to facilitate calibration of any putative nonlinear RF energy conversion occurring within a nonlinear test-piece inside the cavity. The method is validated computationally and experimentally using a well-characterised nonlinear device. The variations of the reflection coefficients of the fundamental and second harmonic responses of the cavity due to adding nonlinear and lossy material are also discussed. The proposed model demonstrates that the sensitivity of the measurement equipment plays a vital role in deciding the required input power to detect any second harmonic signal, which is expected to be very weak. The model developed here enables the establishment of a lookup table giving the level of the second harmonic signal in the detector as a function of the specific input power applied in a measurement. Experimental results are in good agreement with the simulated results. / Engineering and Physical Science Research Council through Grant EP/E022936A

In microwave communications, the main aspects for affecting the dielectric losses in the materials are relating to the dielectric properties and the radiation frequencies. Normally, the different dielectric materials will lead to the different losses and reflections for microwave frequencies. To evaluate the dielectric properties from the different materials plays an essential role in the microwave engineering. There are many approaches can be used to measure the dielectric materials, e.g. capacitor methods, transmission line methods, cavity resonator methods, open cavity methods and so on. The cavity resonator method is one of the most popular ways for measuring the dielectric materials. In this thesis, some of the techniques will be reviewed, and the TM010 mode cylindrical cavity resonator with perturbation technique will be used for determining the dielectric properties. The design and measurements will be presented in both simulations and practice. With 1.2GHz cavity resonator, in the simulations, the dielectric permittivity for Teflon is measured as 2.09-0.0023i and 2.12-0.0116 in copper cavity and ferromagnetic cavity. Finally the sample is measured as 3.83-0.12i in practice.

Polyetherimide/(Ba0.8Sr0.2)(Ti0.9Zr0.1)O3 (PEI/BSTZ8291) composites are fabricated using PEI, dispersant, solvents, and BSTZ powder. The effects of the content of BSTZ8291 filler on the chemical, physical, mechanical and dielectric properties of PEI/BSTZ8291 composites are studied in this paper. As the content of BSTZ filler increases from 10 wt% to 70 wt%, the relative permittivity of PEI/BSTZ8291 composites at 1 MHz increase from 2.58 to 17.71. The measurement of relative permittivity of PEI/BSTZ8291 composites is developed using the ¡§Rectangular Cavity Resonator¡¨ method from 1 GHz to 13.5 GHz. The relative permittivity is calculated by observing the frequencies of resonant cavity modes. The relative permittivity of PEI/BSTZ8291 composites is almost unchanged as the measured frequency increases from 1 GHz to 13.5 GHz. The presented characteristics are better than those of polymer/BaTiO3 composites. The improvement in the tensile strength of PEI/BSTZ8291 composites may be caused by the increased interactions between neat PEI and BSTZ8291 ceramic powder, and no phase separation phenomenon occurred. The Young¡¦s modulus of the PEI/BSTZ8291 composites is improved by about 58% as the content of BSTZ8291 filler from 0 to 50 wt% and the elongation at break of the composites decreases as the content of BSTZ8291 filler increases, indicating that the composite becomes somewhat brittle as compared with neat PEI. PEI/BSTZ8291 composite substrates are developed for the applications of circularly polarized (CP) antennas. A CP antenna with a simple structure is developed as the ultra high frequency (UHF) band radio frequency identification (RFID) reader application. The fabricated antenna has an impedance bandwidth spanning from 901 to 949 MHz, which covers the entire band of Taiwan UHF-RFID frequency. The measured return loss, Smith chart, axial ratio, radiation patterns and CP gain characteristics of antennas fabricated on PEI/BSTZ8291 composites are excellent in the band of Taiwan UHF-RFID frequency. It is demonstrated that the CP antenna fabricated on PEI/BSTZ substrate has the better characteristics and small size than those fabricated on FR4 substrate.

This dissertation presents design challenges and promising solutions for temperature and pressure sensors which are highly desirable for harsh-environment applications, such as turbine engines. To survive the harsh environment consisting of high temperatures above 1000°C, high pressures around 300 psi, and corrosive gases, the sensors are required to be robust both electrically and mechanically. In addition, wire connection of the sensors is a challenging packaging problem, which remains unresolved as of today. In this dissertation, robust ceramic sensors are demonstrated for both high temperature and pressure measurements. Also, the wireless sensors are achieved based on microwave resonators. Two types of temperature sensors are realized using integrated resonator/antennas and reflective patches, respectively. Both types of the sensors utilize alumina substrate which has a temperature-dependent dielectric constant. The temperature in the harsh environment is wirelessly detected by measuring the resonant frequency of the microwave resonator, which is dependent on the substrate permittivity. The integrated resonator/antenna structure minimizes the sensor dimension by adopting a seamless design between the resonator sensor and antenna. This integration technique can be also used to achieve an antenna array integrated with cavity filters. Alternatively, the aforementioned reflective patch sensor works simultaneously as a resonator sensor and a radiation element. Due to its planar structure, the reflective patch sensor is easy for design and fabrication. Both temperature sensors are measured above 1000°C. A pressure sensor is also demonstrated for high-temperature applications. Pressure is detected via the change in resonant frequency of an evanescent-mode resonator which corresponds to cavity deformation under gas pressure. A compact sensor size is achieved with a post loading the cavity resonator and a low-profile antenna connecting to the sensor. Polymer-Derived-Ceramic (PDC) is developed and used for the sensor fabrication. The pressure sensor is characterized under various pressures at high temperatures up to 800°C. In addition, to facilitate sensor characterizations, a robust antenna is developed in order to wirelessly interrogate the sensors. This specially-developed antenna is able to survive a record-setting temperature of 1300°C.