Numerical simulations of Mach shock reflections have shown that the Mach stem can bifurcate as a result of the slip line jetting forward. Numerical simulations were conducted in this study which determined that these bifurcations occur when the Mach number is high, the ramp angle is high, and specific heat ratio is low. It was clarified that the bifurcation is a result of a sufficiently large velocity difference across the slip line which drives the jet. This bifurcation phenomenon has also been observed after triple point collisions in detonation simulations. A triple point reflection was modelled as an inert shock reflecting off a wedge, and the accuracy of the model at early times after reflection indicates that bifurcations in detonations are a result of the shock reflection process. Further investigations revealed that bifurcations likely contribute to the irregular structure observed in certain detonations.

In this study, we focus on the electric optical characteristic of guest/host polymer system. The charge transfer chromophore Wu182 which contain fluorine atom in it was mixed with polymer PMMA and solved in chloroform, while DR1/PMMA served as reference sample. The wu182/PMMA and DR1/PMMA thin films were produced by spin coating. The thin film was poled at the temperature above glass transition temperature until the second harmonic generation signal was present. The poled thin film was placed in one arm of Mach-Zehnder interferometer. Voltage modulation applied to the polymer films can cause phase changes in the interferometer from that we estimate the electro-optic coefficient. From our experiments, we found that modulating frequency had significant influence on the electro-optic effect. The result shows that Wu182 possess large nonlinear optical coefficient. The valid electro-optic coefficient r13 was obtained to be 2.620 pm/V when the frequency was above 6 kHz.

The interferometeric optical fiber sensor has high sensitivity for sound signal. This characteristic is used to design hydrophones. The sound pressure causes the optical fiber to change its shape. So as to induce phase difference between sensing and reference arms. Using the demodulation system, we can get the signal we want. In this thesis, we plan to analyze three different kinds of optic configurations, such as Michelson, compensating Mach-Zehnder, hybrid configuration of Mach-Zehnder and Sagnac interferometers. The mathematical methods are used to compare their characters. We also use software to simulate the relation among sensitivity, delay fiber and frequency character of the Sagnac interferometer. In our experiment, we use PGC modulation technology and compare the results with a standard hydrophone B&K 8103 for calibration. We also measure the dynamic range of proposed three interferometers. The measurement result of this paper is as following: Michelson and compensating type Mach-Zehnder interferometer dynamic range were about 24.90 dB and 13.98 dB, the acoustic signal sensitivity was -201.67 dB re V/1uPa and -205.97 dB re V/Pa, respectively. The dynamic range of the hybrid of Mach-Zehnder and Sagnac type interferometer was 33.67 dB and acoustic signal sensitivity was -212.47 dB re V/1uPa.

The goal of the thesis is to fabricate the integrated asymmetric Mach-Zehnder Interferometer and Optical waveguide Ring Resonator with simple fabrication process. A 1.49

Due to the property of the photonic crystal, like bandgap, many researches on them are discussed. Photons with wavelength within the bandgap cannot propagate through the crystal. Then placing some defects in the crystal, because the periodic arrangement is destroyed, it is possible to build a waveguide to guide light along certain path. One kind is coupled cavity waveguide. The photons can propagate in a coupled-cavity waveguide by coupling without radiation losses. So it is widely used to implement a variety of optical devices. In this thesis, we use coupled cavity waveguide to construct devices. And the characteristics of Mach-Zehnder interferometer and power splitter are discussed. Then we propose two logic gate structures with an input port and two control ports. The state of control port determines the electric field at the output port. Besides, the four-port channel drop filter is proposed. It will make the three wavelengths ¢w1310, 1490 and 1550 nm¢w propagate in different waveguides. So it could be used as a wavelength demultiplexer for FTTH. Finally, the property of the PC-based rat-race circuit is investigated. By adjusting the phase of the control signal, we could decide the input signal to exit from output 1 or output 2. In this way, we could use it to function as a switch.

The reflection wavelength of Fiber Bragg Grating is sensitive to the strain and the temperature¡¦s variation. We use Fiber Bragg Grating to be the sensor head and measure the vibration frequency in constant temperature environment. The vibration of object can make the sinusoidal strain to Fiber Bragg Grating, and it will make a little phase difference to the light of the fiber. Using the interferometer and demodulation system, we can measure the phase difference and vibration frequency. Our sensor configuration is made up of imbalance Mach-Zehnder interferometer and Fiber Bragg Grating. The two light of different path need different time to pass through the vibration source, so they make phase difference. We use the demodulation circuit to measure the phase difference causing by vibration and get the vibration frequency. Our experiment structure is a novel configuration of Fiber Bragg Grating vibration sensor. Its intensity of signal is larger than the intensity of original sensor configuration, about 4dB.The novel sensor configuration is easier spread than traditional accelerometer and it is designed of all fiber. The accuracy for measuring low frequency vibration is 99.971%. The Dynamic range of the system is more than 45dB. It is larger than the dynamic range of original sensor configuration, about 9dB. The smallest signal that can be measured is about 0.0075rad.

Abstract The electrical microphone has came to maturity, which has some restrictions on high electromagnetic and wet environments¡CFiber-Optic sensor can improve the problems, because it has better characters in electromagnetic interference and wet environment than the traditional microphone. The structure of Sagnac interferometer is circulator, so the design of head to a sensor has to wind fiber around. Because the minimum radius of winded fiber has a threshold, we can not miniaturize the sensor-head. A typical Mach-Zehnder interferometer has to use high-coherence light source and the length of two arms in equality without any interference, so it is difficult in fabrication. If we make a microphone by FBG and Mach-Zehnder interferometer, and the advantage is that we can use low-coherence light source, and shorten the length of two arms in interferometer. By using the structure, the minimum measured pressure of sound is 0.6 Pa, and the dynamic range is 30dB.

In this thesis, the Leishman-Beddoes method of determining airloads for an airfoil undergoing dynamic stall is studied over a range of Mach numbers. To validate the method for conditions where little experimental data is available, a computational fluid dynamics solver is utilized to provide airload predictions for comparison to the Leishman-Beddoes results. It is found that even for high Mach numbers the Leishman-Beddoes method provides reliable predictions for lift coefficient. However, at the higher Mach numbers pitching moment is sometimes overpredicted at high angle of attack. This is seemingly due to an inability to accurately determine the center of pressure in the high speed unsteady flow environment.

Numerical simulations of Mach shock reflections have shown that the Mach stem can bifurcate as a result of the slip line jetting forward. Numerical simulations were conducted in this study which determined that these bifurcations occur when the Mach number is high, the ramp angle is high, and specific heat ratio is low. It was clarified that the bifurcation is a result of a sufficiently large velocity difference across the slip line which drives the jet. This bifurcation phenomenon has also been observed after triple point collisions in detonation simulations. A triple point reflection was modelled as an inert shock reflecting off a wedge, and the accuracy of the model at early times after reflection indicates that bifurcations in detonations are a result of the shock reflection process. Further investigations revealed that bifurcations likely contribute to the irregular structure observed in certain detonations.

This thesis report works on optically characterizing waveguide based biosensors consisting of thin, narrow Au stripes embedded in CYTOP. The devices were examined using an ever evolving and improving interrogation setup, variations of which are described in detail in this document. A number of changes were made to the setup configuration in order to reduce noise levels and increase efficiency and accuracy of acquired measurements. Waveguides of varying configurations (straight waveguides and Mach-Zehnder Interferometers with etched and cladded channels) are described and optically characterized. The characterization results of these devices are presented in this thesis. Bulk index measurements are carried out in order to determine a suitable bio-sensing solution with a refractive index matched to that of CYTOP. Step index measurements clearly distinguishing the introduction of sensing solutions of refractive indices varying from one another, are made available. Preliminary bio-sensing experiments involving detection of change in refractive index of sensing fluid as well as adlayer thickness with the introduction of analytes binding to the waveguide surface that has been functionalized with antibodies, using both straight and cladded waveguides with single mode outputs are studied.