Optics Commons^™

Suppression Of Dynamic Aeroelastic Response Of A Semispan Wing Using Traditional And Distributed Sensing, James Ramey

Mechanical & Aerospace Engineering Theses & Dissertations

Characterization and management of aeroelastic effects are a vital part of aircraft design. Mitigation of these effects often includes control systems to suppress the vibrations. Control systems are constantly being developed and improved, with one such avenue of development being new sensing systems that can increase the information fed into the controller. Fiber Optic Strain Sensing (FOSS) technology is one such system that utilizes Fiber Bragg Gratings (FBGs) on a fiber optic cable to sense the strain on structural elements. This system has promise as a high-density feedback device, and the maturation of the technology has allowed assessment of its …

Fiber Optic Sensors For Industry And Military Applications, Yiyang Zhuang

Doctoral Dissertations

"Fiber optic sensors (FOSs) have been widely used for measuring various physical and chemical measurands owing to their unique advantages over traditional sensors such as small size, high resolution, distributed sensing capabilities, and immunity to electromagnetic interference. This dissertation focuses on the development of robust FOSs with ultrahigh sensitivity and their applications in industry and military areas.

Firstly, novel fiber-optic extrinsic Fabry-Perot interferometer (EFPI) inclinometers for one- and two-dimensional tilt measurements with 20 nrad resolution were demonstrated. Compared to in-line fiber optic inclinometers, an extrinsic sensing motif was used in our prototype inclinometer. The variations in tilt angle of the …

Microfiber Coupler Based Label-Free Immunosensor, Lin Bo, Christy Charlton O'Mahony, Yuliya Semenova, Niamh Gilmartin, Pengfei Wang, Gerald Farrell

Articles

Optical microfibers and related structures which incorporate large evanescent field and minimal size offer new opportunities for biosensing applications. In this paper we report the development of an immunosensor based on a tapered microfiber coupler embedded in a low refractive index polymer. Biomolecules adsorbed on the microfiber coupler surface modify the surrounding refractive index. By immobilizing antigens on the surface of the sensing area, the microfiber coupler was able to operate as a label-free immunosensor to detect specific antibodies. We experimentally demonstrated for the first time the sensing ability of this sensor using a fibrinogen antigen-antibody pair. By monitoring the …

Spectral Engineering Of Optical Fiber Preforms Through Active Nanoparticle Doping, T. Lindstrom, E. Garber, D. Edmonson, T. Hawkins, Y. Chen, G. Turri, M. Bass, J. Ballato

Publications

Europium doped alkaline earth fluoride [Eu:AEF2 (AE = Ca, Sr, Ba)] nanoparticles were synthesized and systematically incorporated into the core of modified chemical vapor deposition (MCVD)-derived silica-based preforms by solution doping. The resulting preforms were examined to determine the impact of the nanoparticles chemistry on the spectroscopic behavior of the glass. The dominant existence of Eu3+ was demonstrated in all preforms, which is in contrast to conventional solution doped preforms employing dissolved europium salts where Eu2+ is primarily observed. Raman spectroscopy and fluorescence lifetime measurements indicated that the nanoparticles composition is effective in controlling, at a local chemical and structural …

Diffusion Of Rubidium Vapor Through Hollow-Core Fibers For Gas-Phase Fiber Lasers, Eric M. Guild

Theses and Dissertations

This work examines the diffusion of rubidium through a small diameter tube alone and in the presence of noble gases. A fluid dynamics analysis is investigated to aid in choosing a method for transferring atomic rubidium vapor that is reliable and efficient. Solutions to the time dependant ordinary differential equation describing the experimental flow properties of the system reveal more precise outcomes than previously practiced routines. Resolved viscosities and Poiseuille flow theory velocity profile distributions are characterized for noble gas carriers of the rubidium vapor. Applying Reynolds Numbers to the flow experiments provides pressure differential boundaries that are employed in …

Design And Simulation Of Silica-On-Silicon Pump/Signal Multiplexer For Hybrid Passive-Active Optical Devices., Alvin Law Wen Pin

Student Works (2010-2019)

This dissertation describes the design and simulation of silica-on-silicon pump/signal multiplexer for hybrid passive-active optical devices. Uniform symmetric directional couplers and planar Bragg gratings were utilized in this work, forming the essential building blocks in a waveguide amplifier. Several designs in relation to the multiplexers are presented in this work, with the simplest application for the directional coupler as a pump/signal multiplexer. A 980/1550 nm and an 800/1310 nm pump/signal multiplexers for erbium doped and bismuth doped waveguide amplifier, respectively were modeled. These couplers were designed and simulated in Rsoft BeamPROP environment, utilizing 3D Finite Difference Beam Propagation Method (FD-BPM) …

Nonlinear Fiber Lasers Using Bismuth Based Erbium Doper Fiber Amplifier., Sharifeh Shahi

Student Works (2010-2019)

A thorough study on Bismuth-based Erbium-doped fiber (Bi-EDF) is presented for wide-band amplifiers and multi-wavelength fiber laser applications. This fiber allows high Erbium ions concentration to be doped without a significant concentration quenching effect. The high refractive index characteristic in the Bi-EDF has broadened the emission spectrum of Erbium ions to achieve a broader gain spectrum up to extended L-band region compared to normal silica-based Erbium-doped fiber (EDF). The Bi-EDFA performances have been investigated in terms of power conversion efficiency (PCE), quantum conversion efficiency (QCE), gain and noise figure. The highest QCE and PCE for a 215 cm long of …

Stimulated Brillouin Scattering Phase Conjugation In Fiber Optic Waveguides, Steven M. Massey

Theses and Dissertations

The objective of this research effort was to demonstrate the path to continuous wave, coherent beam combination through stimulated Brillouin scattering phase conjugation in optical fiber. This work experimentally determined the fiber parameters necessary for phase conjugation in step-index optical fiber. Continuous wave phase conjugation using stimulated Brillouin scattering in step-index fibers was achieved for the first time with a fidelity of 0.8 and a threshold power of 16 W in a 15-m fiber with 0.13 NA. A fidelity of 0.8 was also achieved using 40 m of fiber with 0.06-NA and a threshold power of 15 W. The fidelity …

Modeling Of Sbs Phase Conjugation In Multimode Step Index Fibers, Justin B. Spring

Theses and Dissertations

Stimulated Brillouin scattering in a multimode step-index fiber can be used to generate a counter-propagating, phase-conjugate beam that would prove useful in many applications, such as near diffraction limited, double-pass high-power amplifiers or coherent beam combination. Relatively little modeling of such a fiber-based phase conjugator has been done, making design decisions regarding type and length of fiber largely guesswork. A numerical model was constructed with the aim of providing educated predictions about the phase conjugate fidelity that could be expected from a given pump intensity input coupled into a specific fiber. A numerical perturbation algorithm was constructed to search for …

Collision Broadening Using Alkali-Filled, Hollow Core Fibers, Luke P. Rodgers

Theses and Dissertations

The goal of this research was to demonstrate the possibility of collision broadening in a cesium-filled, hollow-core fiber as an alternative to the proven technique of pressure broadening. Theoretically, alkali electrons should relax from the ²P_3/2 to the ²P_1/2 level and the absorption spectrum should collisionally broaden due to the presence of fiber walls, as opposed to the more common pressure broadening method. An absorption dip located at 852.34nm was recorded in a pressure broadened comparison leg. This data was used as a baseline during analysis of the fiber leg's data. While the fiber was successfully …

Direct Diode Pumped Raman Amplifier Based On A Multimode Graded Index Fiberr, Charles James Baird

Theses and Dissertations

The direct pumping of a Raman fiber amplifier (RFA) was attempted using an array of four 25W, fiber pigtailed diodes at 936nm, combined via a 7 channel fiber beam combiner. The initial attempt was conducted using a 1.8 km, 100 micron core, GRIN fiber with an NA of .29 and attenuation 3.6 dB/km at 936nm. While amplification was not achieved, over 200mW of conversion was shown, with 10.4W of pump power and 3.5W of seed. This corresponds to an average conversion efficiency of 2.2%. The subsequent effort utilized a 2km long, 200 micron core, GRIN fiber, with NA of .27 …

Phasing A Dual Optical Path System Using An Optical Fiber As A Phase Conjugate Mirror, Shawn M. Willis

Theses and Dissertations

Phase conjugation properties of stimulated Brillouin scattering (SBS) in a short multimode fiber have been investigated with an eye towards its application for a multi-channel double pass master oscillator power amplifier (MOPA) system. In particular, properties of the SBS beam to compensate for the axial and transverse phase distortion between individual channels in a multi-channel amplifier system were studied. Two optical paths were created by covering half of the laser beam with a microscope slide, and also by spatially splitting the wavefronts with a 4 prism set-up. The Stokes beams that traversed the same optical paths as the pump beams …

Thermal Effects On Y2O3:Eu3+ For Fiber Optic Temperature Sensing, Arnel C. Lavarias

Electrical & Computer Engineering Theses & Dissertations

Fiber optic methods have gained acceptance in the past several years as non­ intrusive optical techniques of measuring environmental variables, particularly under hostile conditions. Fiber optic temperature sensors are required for many applications which have a large operating range. One way to implement this sensor is to introduce rare earth-doped materials into a fiber showing temperature-dependent optical emission characteristics. The thermal effects on optical emission characteristics of Y₂O₃:Eu³⁺ were studied. The thermal broadening and temperature dependence of the lifetime (τ) of the 611.4 nm emission due to the ⁵D₀ ➔ 7F …

Study Of Single-Fiber Fiber Optic Lever Microphone, Trung Duc Nguyen

Electrical & Computer Engineering Theses & Dissertations

Fiber optic sensors are widely used in today's technological applications, providing many advantages that conventional sensors lack. In particular, there is a demand in hypersonic applications to develop microphones to measure acoustic pressure that performs in high temperature and noisy surroundings. This thesis analyzes fiber optic lever microphones (FOLM), since they perform at high temperatures. An FOLM system is an intensity modulated sensor, which is simple to implement and is small in size. Two models of the FOLM have been fabricated and calibrated. The first model uses a seven-element fiber array while the second uses a single-fiber to transmit and …

Design Of A Fiber Optic Image Transmission Link, Justin D. Redd

Theses and Dissertations

An original design is presented for a fiber optic based digital image transmission link operating at a serial bit rate of 250 Mbits/Second. The link is designed as an integral part of an airborne infrared imaging system with particular emphasis on avoiding problems associated with aircraft electromagnetic interference (EMI). Unique features include simplicity (single PC board transmitter and receiver), low power, low cost (under $3,000), and use of the latest off-the-shelf components (including the Gazelle GA9011/GA9012 HOT ROD chip set). Theoretical modeling is used to predict a bit error rate of better than 10^-15, while actual measurements include …