Design of a Resonant Optical Cavity for Imaging Magneto-Optically Active Thin Film Samples

This document describes the design and fabrication of an optical resonator system to investigate magneto-optic properties of thin film samples. This system uses an open-air optical resonator to enable photons to make multiple passes through each thin film and thus increase the magnitude of the Faraday rotation that each sample imposes onto the light that exits the system. This system promises many future experiments to study the magneto-optic properties of thin film and nano-particle samples. Using an optical resonator to enhance Faraday rotation should enable an improved signal-to-noise ratio in taking measurements and images with a photodetector

Increasing the Sensitivity of the Michelson Interferometer through Multiple Reflection

Michelson interferometry has been one of the most famous and popular optical interference system for analyzing optical components and measuring optical metrology properties. Typical Michelson interferometer can measure object displacement with wavefront shapes to one half of the laser wavelength. As testing components and devices size reduce to micro and nano dimension, Michelson interferometer sensitivity is not suitable. The purpose of this study is to design and develop the Michelson interferometer using the concept of multiple reflections. This thesis proposes a new and novel design for a multiple reflection interferometer, where the number of reflections does not affect the quality of the interference. Theoretically we show that more than 1000 reflections can be achieved. Experimental results of greater than 100 reflections are presented in this thesis

Study of Cu/SiO2/Cu Metamaterials: Design, Simulation, Fabrication, Testing, and Optical Applications

In the past few years, “metamaterials” have grabbed attention of researchers in both science and engineering. They have revealed great potentials to realize unusual optical applications such as flat lenses or frequency-selective performances with their unusual electromagnetic properties. In this project, Cu/SiO2/Cu metamaterials of diverse designs and parameters were studied towards discovering their unknown optical applications. From simulation work, it was found that some metamaterials exhibit a performance of a rectangle-shaped bandpass at optical frequencies. Their operational wavelength region can be adjusted by having a different scale of the structure or a different thickness of the constituent materials. This indicates that those metamaterials could be used instead of traditional optical filters. A few selected metamaterials were fabricated and tested for comparison with the simulation results

Design and Implementation of a Microscope Based on Magneto-Optic Effects

When light passes through a medium that is subjected to a strong magnetic field, its polarization state may change due to magneto-optic effects such as Faraday rotation. An imaging system based on this polarization change is designed and constructed. The imaging system is built around a magnetic pulse field generator and able to detect polarization change of the incident light due to magneto-optic effects. An automated scheme is implemented using LabView. The program is developed to integrate all hardware and conduct multiple measurements automatically to enhance sensitivity. Basic testing measurements are conducted to evaluate the performance of the system. A metal film made of 50nm thick nickel and aluminum layer is tested and preliminary results are presented. Apart from the final design and experimental results, problems about laser imaging, system vibration and an early design using simple concave lens are also discussed. While no system can be universally ideal for all kinds of samples, an attempt is made to discuss ideal samples for imaging and how the performance may be affected by other types of samples. Various possible future improvements are also discussed and prioritized

Study of Laser Speckle Scattering in Vitreous Humor Models

When a highly high coherent light propagates through a medium, interactions between light and the medium produces a unique intensity speckle pattern that is dependent on several factors such as particle size in the medium, wavelength of the light, concentration of medium, and scattering angle. Speckle patterns from either static or dynamic specimens have been studied using optical techniques due to its non-invasive nature. Speckle patterns from biological specimens (dynamic) are different from that of the static specimens since random movement of molecules (Brownian motion) in the biological specimen affect the light interactions and thereby the intensity of the speckles in the speckle pattern. Several studies have shown the optical properties of the biological specimen can be characterized using statistical properties from the speckle pattern. A histogram of intensity distribution of the speckle pattern can be used to extract certain optical properties of the specimen such as bioactivity, blood flow, and skin perfusion. In this thesis, a new approach for analyzing biological specimens is presented utilizing a peak shift in the histogram plot (called the Histogram Wavelength Analysis Method) of the intensity of the speckles when changing the wavelength of the incident light. Five different wavelengths were used in a modified slit-lamp equipment for the experiment. Also six different sizes of nanobeads embedded in vitreous humor (biological specimen) were studied. The theory developed for this experimental method matches well with the results and will be presented in the thesi

Study of Surface Plasmon Resonance in Metal and Alloy Nanofilms using Maxwell Description and Metamaterial Simulation in COMSOL

Metamaterials are artificial metallic structures having, possibly, simultaneously negative permittivity and negative permeability which is called a double negative medium. To achieve a visible light range of the metamaterial, the unit cell of the metamaterial units should be 10-200nm. It is a much bigger structure than a size of normal atom. Still, the resolution of fabrication, which is difficult part, should typically be a few nanometers to achieve a nano-level unit. We study Ag thin-film as a convenient candidate for metamaterial over a specific frequency range. Because, the thin film metal is composed of disk shape island structures itself. These represent be each metamaterial unit cell. To model the metamaterial model for each thickness of silver, we use surface plasmon-polaritons which is called SPPs. It can coupled Prism and metal to check where is plasmon resonance angle. This specific angle and the reflectivity of a thin silver film are function of metal and dielectric of thickness and metal’s permittivity and dielectric function of layer. Experimental measurements of SPPs and Simon’s simulation show good agreement with the COMSOL Multiphysics metamaterial model. And we demonstrate the annealing method for a thin film metal is nice approach to change the surface plasmon resonance angle. The theory of SPPs is explained using the Drude model and Maxwell equation

Fabrication and Characterization of Edge-Emitting Semiconductor Lasers

The semiconductor laser was invented in 1962, and has recently become ubiquitous in modern life. This thesis focuses on the development of a semiconductor laser fabricating process which utilizes semiconductor manufacturing technology in a cleanroom environment including photolithography, etching, deposition, and bonding processes. A photomask for patterning is designed, recipes of photolithography process and etching process are developed with experiments. This work gives how to develop the process of fabrication and determine the parameters for each processes. A series of semiconductor laser devices are then fabricated using the developed process and characterization is performed to assess device performance with industrial standard methods. A fabricated device has 18W power and 11% conversion efficiency

Nanoscale tilt measurement using a cyclic interferometer with phase stepping and multiple reflections

High accuracy tilt or roll angle measurement is required for a variety of engineering and scientific applications. Optical interferometry is normally used because it is non-contact and can measure tilt with a very high degree of accuracy. In this thesis, a cyclic interferometer has been developed with four mirrors to measure tilt angles as small as a few nanoradians. To measure the phase, a novel and simple method of phase shift by polarization was developed to enhance measurement sensitivity and accuracy. Since the cyclic interferometer is insensitive to external vibrations and turbulences, polarization phase step was accomplished with relative ease. To introduce the phase shift, a quarter wave plate and a half wave plate were used with a polarized laser beam. Multiple reflections were also introduced in the cyclic interferometer to enhance tilt measurement capability. A new method was developed to evaluate phase and eventually measure the tilt even in the case of changing fringe visibility. The results of these studies show that the multiple reflection cyclic interferometer can be used to measure object tilts in the order of 0.2 nanoradians or 10-5 arc second

A Study of Scattering Characteristics for Micro-scale Rough Surface

Defining the scatter characteristics of surfaces plays an important role in various technology industries such as the semiconductor, automobile, and military industries. Scattering can be used to inspect products for problems created during the manufacturing process and to generate the specifications for engineers. In particular, scattering measurement systems and models have been developed to define the surface properties of a wide variety of materials used in manufacturing. However, most previous research has been focused on very smooth surfaces as a nano-scale roughness. The research in this paper uses the Bidirectional Reflectance Distribution Function (BRDF) and focuses on defining the scattering properties of micro-scale rough and textured surfaces for three different incident angles. Also, the parameters of ABg and Harvey-Shack models are obtained for input into optical design software

Optical Bistability with Two Serially Integrated InP-SOAs on a Chip

A photonic switch using two series-connected, reverse-biased semiconductor optical amplifiers integrated onto a single device has been proposed and switching operation has been verified experimentally. The switching operates on two principles; an electrical bistability arising from the connection of two p-i-n structures in series, and the quantum confined Stark effect in reverse-biased multiple quantum well structures. The result is an electroabsorption modulation of the light through the SOAs due to the alternating voltage states. The system simultaneously produces outputs with both inverted and non-inverted hysteresis behavior, with experimental switching speeds demonstrated up to 400 kHz for a reverse-bias voltage of =2.000V