This thesis focuses on the design of a versatile, portable, and cost-effective fluorescence detection system for LOC devices. Components that are widely available are used, such as LEDs for excitation and a microcontroller for processing. In addition, a photoresistor is tested for the feasibility of being used as a fluorescence detector, instead of the more commonly used photomultiplier tubes. The device also focuses on upgradeability and versatility, meaning that most of the major components can be replaced as long as power requirements remain unaffected. This allows for future additions to the device once they are available, as well as giving the user the power to choose which add-ons are needed since not all users may have the same requirements. The performance of the device after testing with fluorescein dyes and stained yeast cells indicate that it is capable of executing simple tasks, such as determining the presence and concentration of an analyte if given a sufficient amount. It also provided similar readings to commercial fluorescence analysers, which proves its ability to function as a fluorescence detector device. The thesis also proposes a MEMS diffraction grating that can be used for wavelength tuning. By being able to selectively measure across a range of wavelengths, the capability of the device is increased. Examples include being able to detect multiple fluorescent emissions, which will complement the multicoloured excitation LED nicely. In addition, the device will not be limited to a predetermined set of filters. This effectively allows more fluorescent dyes to be used with the device since any wavelength in the visible range can be selectively filtered for. Simulations of the proposed diffraction grating were performed in ANSYS to confirm the validity of the calculated values. In addition, tests were performed on a slide fabricated with diffraction gratings using values as close to the calculated values as possible. All of the results indicate that there is great promise in the proposed diffraction grating design and that it should be further investigated.

Free Spectral Range Matched Interrogation (FSRMI) technique for wavelength demodulation of fiber Bragg grating sensors. We designed and tested a new wavelength demodulation system based on free-spectral-range-matched interrogation which employs a tunable fiber Fabry-Perot interferometer (FPI) and a multi-channel bandpass filter. This technique was deployed to test fiber Bragg gratings (FBG), long period gratings (LPG) and tilted fiber Bragg gratings (TFBG). In the experimental setup, a broadband source launches light into a fiber Bragg grating under test and the reflection/transmission spectrum is fed into a tunable FPI. By tuning an external bias applied to the FPI, the transmission spectrum of FPI scans over a wavelength range. The input optical signal is therefore selectively passed through the FPI and then fed into a four-channel bandpass filter followed by four photodetectors. The optical signal is converted to electrical signal by the photodiodes and is acquired by a data acquisition system. Since a bandpass filter with four channels are used in this interrogation system it can scan four distinguished wavelength ranges simultaneously and thus the scan rate is four time faster. We used this setup for doing some temperature and strain sensitivity measurements on some fiber gratings. Strain sensitivity measurements were done on FBG, TFBG and LPG and temperature sensitivity measurements were performed on TFBG. The strain and temperature sensitivity coefficients of these fiber Bragg grating sensors were obtained from experimental data. Our results show the potential of the integration of the FSRMI system with fiber Bragg gratings for temperature and strain multiple-sensor arrays with high sampling speed and high accuracy.

This thesis focuses on the design of a versatile, portable, and cost-effective fluorescence detection system for LOC devices. Components that are widely available are used, such as LEDs for excitation and a microcontroller for processing. In addition, a photoresistor is tested for the feasibility of being used as a fluorescence detector, instead of the more commonly used photomultiplier tubes. The device also focuses on upgradeability and versatility, meaning that most of the major components can be replaced as long as power requirements remain unaffected. This allows for future additions to the device once they are available, as well as giving the user the power to choose which add-ons are needed since not all users may have the same requirements. The performance of the device after testing with fluorescein dyes and stained yeast cells indicate that it is capable of executing simple tasks, such as determining the presence and concentration of an analyte if given a sufficient amount. It also provided similar readings to commercial fluorescence analysers, which proves its ability to function as a fluorescence detector device. The thesis also proposes a MEMS diffraction grating that can be used for wavelength tuning. By being able to selectively measure across a range of wavelengths, the capability of the device is increased. Examples include being able to detect multiple fluorescent emissions, which will complement the multicoloured excitation LED nicely. In addition, the device will not be limited to a predetermined set of filters. This effectively allows more fluorescent dyes to be used with the device since any wavelength in the visible range can be selectively filtered for. Simulations of the proposed diffraction grating were performed in ANSYS to confirm the validity of the calculated values. In addition, tests were performed on a slide fabricated with diffraction gratings using values as close to the calculated values as possible. All of the results indicate that there is great promise in the proposed diffraction grating design and that it should be further investigated.

Free Spectral Range Matched Interrogation (FSRMI) technique for wavelength demodulation of fiber Bragg grating sensors. We designed and tested a new wavelength demodulation system based on free-spectral-range-matched interrogation which employs a tunable fiber Fabry-Perot interferometer (FPI) and a multi-channel bandpass filter. This technique was deployed to test fiber Bragg gratings (FBG), long period gratings (LPG) and tilted fiber Bragg gratings (TFBG). In the experimental setup, a broadband source launches light into a fiber Bragg grating under test and the reflection/transmission spectrum is fed into a tunable FPI. By tuning an external bias applied to the FPI, the transmission spectrum of FPI scans over a wavelength range. The input optical signal is therefore selectively passed through the FPI and then fed into a four-channel bandpass filter followed by four photodetectors. The optical signal is converted to electrical signal by the photodiodes and is acquired by a data acquisition system. Since a bandpass filter with four channels are used in this interrogation system it can scan four distinguished wavelength ranges simultaneously and thus the scan rate is four time faster. We used this setup for doing some temperature and strain sensitivity measurements on some fiber gratings. Strain sensitivity measurements were done on FBG, TFBG and LPG and temperature sensitivity measurements were performed on TFBG. The strain and temperature sensitivity coefficients of these fiber Bragg grating sensors were obtained from experimental data. Our results show the potential of the integration of the FSRMI system with fiber Bragg gratings for temperature and strain multiple-sensor arrays with high sampling speed and high accuracy.

In this dissertation, the development of an experimental prototype for on-board optical-to-electrical signal broadcasting at 10 Gb/s per channel over an interconnect distance of 10 cm was presented. The optical distribution network was implemented using a polymer-based 1-by-4 multimode interference (MMI) splitter with linearly tapered output facet. A 1-by-8 MMI splitter with input/output waveguides of 10 microns in width was first fabricated using standard photolithography and characterized at 40 Gb/s in NRZ format and PRBS = 2^7-1. The pulse response of MMI devices was further quantified from the time-dependent, pulse-modulated field propagation perspective incorporated with various dispersion mechanisms. The results predict their operating limitations and investigate why and how such devices become non-functional in the ultrashort-pulse limit that is far beyond the most present-day optical systems. The guided-mode attenuation associated with polymer waveguides fabricated on FR-4 printed-circuit boards was also investigated for the first time. The rigorous transmission-line network approach was applied and the FR-4 substrate was treated as a long-period substrate grating with rectangular corrugations. The peaks of attenuation were shown to occur near the Bragg conditions that were recognized as the leaky-wave stop bands. As the buffer layer thickness increases, the attenuation becomes negligibly small that is attributed to the weak grating-induced perturbation to the mode behavior. The prototype was then developed on the basis of both experimental verifications to the devices and theoretical investigations. An improved 1-by-4 MMI splitter at 1550 nm with linearly tapered output facet was heterogeneously integrated with four p-i-n photodetectors (PDs) on a silicon (Si) bench. The Si bench itself was then hybrid integrated onto an FR-4 printed-circuit board with four receiver channels composed of transimpedance amplifiers, limiting amplifiers, and surface-mounted components. The innovative integration approach demonstrated the simultaneous alignment between multiple waveguides and multiple PDs during the MMI fabrication process that is a complete radical departure from the conventional assembly method inherent from the telecommunication industry. The entire system was fully functional at 10 Gb/s per channel.

This thesis describes a method developed to quickly measure the Rayleigh wave Q for a test material using a minimally invasive laser probe. The probe was donated to our lab by Dr. Alex Maznev at Phillips AMS in Natick, Ma. The machine was originally used to measure ultra thin film metal thicknesses; however we have utilized it to suit our needs. The optics head relies on a technique known as the transient grating method to generate a dispersion curve. This dispersion curve is then operated on by a local approximation for the Kramers-Kronig relations. The Kramers-Kronig relations for acoustic waves relate the real and imaginary parts of the dynamic compressibility to one another. The real part of the compressibility relates to the phase velocity of the wave and the imaginary part relates to the attenuation. Once the attenuation for the corresponding range of frequencies is determined the last step is to apply both the dispersion data and the attenuation data to the material Q equation to find Q over a range of frequencies. This thesis discusses the design of the machine, the theory behind the Kramers-Kronig relations and surface acoustic waves, the experimental procedure, and lastly results generated by the technique.

A series of photopolymerizable silica for optical storage has been prepared using sol-gel process in this study. The inorganic-organic hybrid materials were based on methacroloxy-propyl-trimethoxysilane (MPTS) and tetraethylorthosilicate (TEOS). Thin films of the hybrids were prepared using spin coating, knife coating, and the closed-mold methods, while the knife coating showing better film flatness and controlled film thickness. Results indicate crack-free polymerizable silica can be obtained using a recipe with 1 wt% photoinitiator. Samples after irradiation shows increased transmittance, suggesting that photopolymerization did take place with the aid of photoinitiators. Spectroscopic study from FTIR indicates C=C conversion in the acrylic part of MPTS reaches 57.51%. The grating period is observed by the optical microscopy. The maximum diffraction efficiency is 48.21%, as obtained from the sample of pure MPTS. From BET measurements, the pore size of the polymerizable silica increases with the increasing amount of MPTS, consistent with the results from measurements of apparent density. Factors affecting the diffraction efficiency are analyzed; these include sample flatness, sample thickness, the conversion of monomer, and concentration of the photoinitiator. Formation mechanism of the periodic grating is proposed based on this study. Addition of MPTS can greatly alleviate problem of phase separation; yet, movement acrylic segment in MPTS is severely limited. On the other hand, samples with more TEOS tend to be densified more with decreased diffraction efficiency

A tunable guided-wave optical filter that performs spectral slicing at the 1530nm wavelength regime in Ti:LiNbO3 was proposed and fabricated. It is aimed at minimizing crosstalk between channels in dense wavelength division multiplexing (DWDM) optical network applications. The design utilizes a sparse grating allowing the selection of equally spaced channels in the frequency domain. Between selected channels, equally spaced nulls are also produced. The sparse grating is formed by using N coupling regions with different lengths along the direction of propagation of light in the waveguide, generating N-1 equally spaced nulls between adjacent selected channels. The distance between the centers of adjacent coupling regions is kept constant. The filtering is based on codirectional polarization coupling between transverse electric (TE) and transverse magnetic (TM) orthogonal modes in a waveguide through an overlay of strain-induced index grating, via the strain-optic effect. Two types of devices were fabricated. In the first type, the sparse gratings were produced on straight channel waveguides. Selected channels emerge from the device in a polarization state orthogonal to the input and a polarizer is needed to observe the filtered light. For the second type, an asymmetric Mach-Zehnder interferometer configuration was used to eliminate the need of the polarizer at the output, and yields an output response that is polarization independent. Both types of devices were fabricated on x-cut y-propagating LiNbO3 substrates, with N = 6 strain-induced coupling regions. The single mode channel waveguides were formed by Ti diffusion. Electrode patterns centered about the optical waveguide were defined by liftoff. In the straight channel devices, insertion loss was less than 2.5 dB on a 43 mm sample. The 3-dB channel bandwidth of the selected channels is approximately 1.0 nm. Devices were tuned thermally as well as by voltage application to surface electrodes resulting in tuning rates of 1.0 nm/oC and 0.04148 nm/V, respectively. In the polarization independent device the insertion loss for the phase-matched wavelength was 5.3 dB on a 53 mm long chip. The 3-dB bandwidth was also ~1.0 nm and the thermal tuning rate 1.0 nm/oC. The experimental results are in good agreement with design theory.

Azo-Dye Doped Liquid Crystal (DDLC) is a developed material which can be used to fabricate optical shutter, displays, etc. In this thesis, we presents of the transient grating on a planar aligned DDLC. The effect of various polarizations of writing and probing beams, and of temperature on the transient grating are examined. Then, we propose a model to explain the result. Through this study, we understand the factors that determine the light-induced aligning Dye effect on nematic liquid crystals.

Using Long-Period Fiber Gratings as component of Gain-Flattening filter ofOptical Amplifier, and discuss spectrum of different struture of Long-Period Fiber Gratings. To investigate the spectra characteristics of Long-Period fiber Gratings for designing reference resources. Aiming at different Gain-Flattening filter uses different struture of fiber grating, and the decision of parameter of fiber grating using Genetic Algorithm. Finally delcaring the dataflow of designing filter using Long-Period Fiber Grating and conclusion.In this paper , gain flatttening Cr:YAG optical amplifier spectrum and Erbium-doped optical amplifier spectrum,one achieve 300nm bandwidth and another achieve 40nm.