Optics Commons^™

Compressive Direct Imaging Of A Billion-Dimensional Optical Phase Space, Samuel H. Knarr, Daniel J. Lum, James Schneeloch, John C. Howell

Mathematics, Physics, and Computer Science Faculty Articles and Research

Optical phase spaces represent fields of any spatial coherence and are typically measured through phase-retrieval methods involving a computational inversion, optical interference, or a resolution-limiting lenslet array. Recently, a weak-values technique demonstrated that a beam's Dirac phase space is proportional to the measurable complex weak value, regardless of coherence. These direct measurements require raster scanning through all position-polarization couplings, limiting their dimensionality to less than 100 000 [C. Bamber and J. S. Lundeen, Phys. Rev. Lett. 112, 070405 (2014)]. We circumvent these limitations using compressive sensing, a numerical protocol that allows us to undersample, yet efficiently measure, high-dimensional phase spaces. …

In Vivo Vascular Imaging With Photoacoustic Microscopy, Hsun-Chia Hsu

McKelvey School of Engineering Graduate Student Theses & Dissertations

Photoacoustic (PA) tomography (PAT) has received extensive attention in the last decade for its capability to provide label-free structural and functional imaging in biological tissue with highly scalable spatial resolution and penetration depth. Compared to modern optical modalities, PAT offers speckle-free images and is more sensitive to optical absorption contrast (with 100% relative sensitivity). By implementing different regimes of optical wavelength, PAT can be used to image diverse light-absorbing biomolecules. For example, hemoglobin is of particular interest in the visible wavelength regime owing to its dominant absorption, and lipids and water are more commonly studied in the near-infrared regime.

In …

Automating Mobile Device File Format Analysis, Richard A. Dill

Theses and Dissertations

Forensic tools assist examiners in extracting evidence from application files from mobile devices. If the file format for the file of interest is known, this process is straightforward, otherwise it requires the examiner to manually reverse engineer the data structures resident in the file. This research presents the Automated Data Structure Slayer (ADSS), which automates the process to reverse engineer unknown file for- mats of Android applications. After statically parsing and preparing an application, ADSS dynamically runs it, injecting hooks at selected methods to uncover the data structures used to store and process data before writing to media. The resultant …

Scattering Of Few Photon Fields By Two Level Systems In A One Dimensional Geometry, William Konyk

Graduate Theses and Dissertations

Recent experimental progress has realized strong, efficient coupling of effective two level systems to waveguides. We study the scattering of multimode photons from such emitters coupled losslessly to the confined geometry of a one dimensional waveguide. We develop novel techniques for describing the scattered state of both single and multi-photon wavepackets and explore how such wavepackets interact with arrays of emitters coupled to a one dimensional waveguide. Finally, we apply these techniques and analyze the capability of two particular systems to act as a quantum conditional logic gate.

Room Temperature Operation Of Quantum Cascade Lasers Monolithically Integrated Onto A Lattice-Mismatched Substrate, Rowel Go

Electronic Theses and Dissertations

Quantum Cascade Lasers (QCLs) are semiconductor devices that, currently, have been observed to emit radiation from ~ 2.6 μm to 250 μm (1 to 100 terahertz range of frequencies.) They have established themselves as the laser of choice for spectroscopic gas sensing in the mid-wavelength infrared (3-8 μm) and long-wavelength infrared (8-15 μm) region. In the 4-12 μm wavelength region, the highest performing QCL devices, in terms of wall-plug efficiency and continuous wave operation, are indium phosphide (InP) based. The ultimate goal is to incorporate this InP-based QCL technology to silicon (Si) substrate since most opto-electronics are Si-based. The main …

A System For Conducting Laser-Induced Fluorescence Measurements On Gas Mixtures Exposed To Alpha Radiation, Patrick Ables

Master's Theses

This paper documents modifications to an existing vacuum system to allow laser-induced fluorescence spectroscopy measurements within simulated atmospheres under a variety of conditions. This added capability will expand the laboratory’s ability to experimentally validate a computational model that calculates the effects of radiation within the atmosphere. The computational model could reveal radiation-induced chemical products that can be used to develop an alternative detection method that can be implemented from a safe distance. The selection of molecules for experimental validation has been limited to those which can be detected utilizing cavity ringdown spectroscopy. The current model indicates nitric oxide and ozone …

Compensation Of Non-Linear Bandwidth Broadening By Laser Chirping In Thomson Sources, C. Maroli, V. Petrillo, I. Drebot, L, Serafini, B. Terzić, G. A. Krafft

Physics Faculty Publications

A new laser chirping prescription is derived by means of the phase-stationary method for an inci- dent Gaussian laser pulse in conjunction with a Li enard-Wiechert calculation of the scattered radia- tion flux and spectral brilliance. This particularly efficient laser chirp has been obtained using the electric field of the laser and for electrons and radiation on axis. The frequency modulation is some- what reduced with respect to that proposed in the previous literature, allowing the application of this procedure to lasers with larger values of the parameter a₀. Numerical calculations have been performed using mildly focused and …

Thermally Stable Hybrid Cavity Laser Based On Silicon Nitride Gratings, Simone Iadanza, Andrei P. Bakoz, Praveen K. J. Singaravelu, Danilo Panettieri, Stefan Schulz, Ganga Chinna Rao Devarapu, Sylvain Guerber, Charles Baudot, Frédéric Boeuf, Stephen Hegarty, Liam O'Faolain

Cappa Publications

In this paper, we show the experimental results of a thermally stable Si3N4 external cavity (SiN EC) laser with high power output and the lowest SiN EC laser threshold to our knowledge. The device consists of a 250 μm sized reflective semiconductor optical amplifier butt-coupled to a passive chip based on a series of Si3N4 Bragg gratings acting as narrow reflectors. A threshold of 12 mA has been achieved, with a typical side-mode suppression ratio of 45 dB and measured power output higher than 3 mW. Furthermore, we achieved a mode-hop free-lasing regime in the range of 15–62 mA and …

Investigation Of Spin And Dip-Coating Phase Change Chalcogenide Materials As A Novel Technique For Coating And Functionalizing Conformal Optics, Paul Vecchio

Physics and Astronomy Summer Fellows

Chalcogenide glasses (ChGs) have excellent infrared (IR) transparency ranging up to 20 μm, large nonlinear refractive indices, and tailorable thermo-optic coefficients (dn/dT) that have great potential for applications in detectors, sensors, waveguides, imaging devices, photonic waveguides, acousto-optics, and optical devices. Spin and dip coating ChGs from solution is a low-cost, simple, and scalable method for depositing films over a large area. In this study, we utilize the novel approach of spin and dip coating to create thin ChG films of arsenic trisulfide (As₂S₃) and arsenic selenide (As₂Se₃). To realize the full potential …

Nanostructured Fibers As A Versatile Photonic Platform: Radiative Cooling And Waveguiding Through Transverse Anderson Localization, Norman Nan Shi, Cheng-Chia Tsai, Michael J. Carter, Jyotirmoy Mandal, Adam C. Overvig, Matthew Y. Sfeir, Ming Lu, Catherine L. Craig, Gary D. Bernard, Yuan Yang, Nanfang Yu

Publications and Research

Broadband high reflectance in nature is often the result of randomly, three-dimensionally structured materials. This study explores unique optical properties associated with one-dimensional nanostructures discovered in silk cocoon fibers of the comet moth, Argema mittrei. The fibers are populated with a high density of air voids randomly distributed across the fiber cross-section but are invariant along the fiber. These filamentary air voids strongly scatter light in the solar spectrum. A single silk fiber measuring ~50 μm thick can reflect 66% of incoming solar radiation, and this, together with the fibers' high emissivity of 0.88 in the mid-infrared range, allows …

Novel Compact Narrow-Linewidth Mid-Infrared Lasers For Sensing Applications, Behsan Behzadi

Optical Science and Engineering ETDs

The mid-infrared (2-14 μm) spectral region contains the strong absorption lines of many important molecular species, which make this region crucial for several well-know applications such as spectroscopy, chemical and biochemical sensing, security, and industrial monitoring. To fully exploit this region through absorption spectroscopic techniques, compact and low-cost narrow-linewidth (NLW) mid-infrared (MIR) laser sources are of primary importance.

This thesis is focused on three novel compact NLW MIR lasers: demonstration and characterization of a new glass-based spherical microlaser, investigation of the performance of a novel fiber laser, and the design of a monolithic laser on a silicon chip. Starting with …

Laser-Induced Recoverable Surface Patterning On Ni50ti50 Shape Memory Alloys, Saidjafarzoda Ilhom

Masters Theses & Specialist Projects

Shape memory alloys (SMAs) are a unique class of smart materials exhibiting extraordinary properties with a wide range of applications in engineering, biomedical, and aerospace technologies. In this study, an advanced, efficient, low-cost, and highly scalable laser-assisted imprinting method with low environmental impact to create thermally controllable surface patterns is reported. Two different imprinting methods were carried out mainly on Ni50Ti50 (at. %) SMAs by using a nanosecond pulsed Nd:YAG laser operating at 1064 nm wavelength and 10 Hz frequency. First, laser pulses at selected fluences were directly focused on the NiTi surface, which generated pressure pulses of up to …

Design, Fabrication, And Characterization Of A One-Dimensional Single-Material Polarizing Photonic Crystal, Ehsan Ordouie

Graduate Theses - Physics and Optical Engineering

We examine a multilayered one-dimensional (1D) polarizing photonic crystal designed and fabricated out of a single material. This polarizer is designed for high reflection of the s polarization and low reflection of p polarization at the wavelength of 632.8 nm. This device is fabricated implementing the oblique angle deposition technique to produce six-bilayers of alternating high to low indices of titanium dioxide using e-beam PVD for depositing on top of a fused silica substrate. For modeling, we used transfer-matrix method and numerical finite-difference time-domain analysis to simulate behavior of the 1D photonic bandgap structure. Both model and simulation predict better …

Broadband Measurement And Reduction Of Quantum Radiation Pressure Noise In The Audio Band, Jonathan Daniel Cripe

LSU Doctoral Dissertations

One hundred years after Albert Einstein predicted the existence of gravitational waves in his general theory of relativity, the Laser Interferometer Gravitational-Wave Observatory (LIGO) made the first direct detection of gravitational waves. Since the first detection of gravitational waves from a binary black hole merger, LIGO has gone on to detect gravitational waves from multiple binary black hole mergers, and more recently from a binary neutron star merger in collaboration with telescopes around the world. The detection of gravitational waves has opened a new window to the universe and has launched the era of gravitational wave astronomy.

With the first …

Super‐Resolution Imaging Of Amyloid Structures Over Extended Times By Using Transient Binding Of Single Thioflavin T Molecules, Kevin Spehar, Tianben Ding, Yuanzi Sun, Niraja Kedia, Jin Lu, George R. Nahass, Matthew D. Lew, Jan Bieschke

Electrical & Systems Engineering Publications and Presentations

Oligomeric amyloid structures are crucial therapeutic targets in Alzheimer's and other amyloid diseases. However, these oligomers are too small to be resolved by standard light microscopy. We have developed a simple and versatile tool to image amyloid structures by using thioflavin T without the need for covalent labeling or immunostaining. The dynamic binding of single dye molecules generates photon bursts that are used for fluorophore localization on a nanometer scale. Thus, photobleaching cannot degrade image quality, allowing for extended observation times. Super‐resolution transient amyloid binding microscopy promises to directly image native amyloid by using standard probes and record amyloid dynamics …

Imaging The Three-Dimensional Orientation And Rotational Mobility Of Fluorescent Emitters Using The Tri-Spot Point Spread Function, Oumeng Zhang, Jin Lu, Tianben Ding, Matthew D. Lew

Electrical & Systems Engineering Publications and Presentations

Fluorescence photons emitted by single molecules contain rich information regarding their rotational motions, but adapting single-molecule localization microscopy (SMLM) to measure their orientations and rotational mobilities with high precision remains a challenge. Inspired by dipole radiation patterns, we design and implement a Tri-spot point spread function (PSF) that simultaneously measures the three-dimensional orientation and the rotational mobility of dipole-like emitters across a large field of view. We show that the orientation measurements done using the Tri-spot PSF are sufficiently accurate to correct the anisotropy-based localization bias, from 30 nm to 7 nm, in SMLM. We further characterize the emission anisotropy …

Efficient Phase Retrieval For Off-Axis Point Spread Functions, Salome Esteban Carrasco

Theses and Dissertations

A novel pairing of phase retrieval tools allows for efficient estimation of pupil phase in optical systems from images of point spread functions (PSFs). The phase retrieval algorithm uses correlation of modeled phase in the focal plane to decouple aberrations that are difficult to identify in complex PSFs. The use of a phase kernel that departs from the Fresnel approximation for off-axis PSFs is a more accurate representation of wavefront phase in finite conjugate imaging. The combination of the approximation and phase correlation algorithm can be more efficient and accurate than generic algorithms.

Rotation Of Two-Petal Laser Beams In The Near Field Of A Spiral Microaxicon, S. S. Stafeev, Liam O'Faolain, M. V. Kotlyar

Cappa Publications

Using a spiral microaxicon with the topological charge 2 and NA = 0.6 operating at a 532-nm wavelength and fabricated by electron-beam lithography, we experimentally demonstrate the rotation of a two-petal laser beam in the near field (several micrometers away from the axicon surface). The estimated rotation rate is 55 °/mm and linearly dependent on the on-axis distance, with the theoretical rotation rate being 53 °/mm. The experimentally measured rotation rate is found to be linear and coincident with the simulation results only on the on-axis segment from 1.5 to 3 mm. The experimentally measured rotation rate is 66 °/mm …

Short-Wave Infrared Compressive Imaging Of Single Photons, Thomas Gerrits, Daniel J. Lum, Varun B. Verma, John C. Howell, Richard P. Mirin, Sae Woo Nam

Mathematics, Physics, and Computer Science Faculty Articles and Research

We present a short-wave infrared (SWIR) single photon camera based on a single superconducting nanowire single photon detector (SNSPD) and compressive imaging. We show SWIR single photon imaging at a megapixel resolution with a low signal-to-background ratio around 0.6, show SWIR video acquisition at 20 frames per second and 64x64 pixel video resolution, and demonstrate sub-nanosecond resolution time-of-flight imaging. All scenes were sampled by detecting only a small number of photons for each compressive sampling matrix. In principle, our technique can be used for imaging faint objects in the mid-IR regime.

Frequency Modulated Continuous Wave Compressive Depth Mapping, Daniel J. Lum, Samuel H. Knarr, John C. Howell

Mathematics, Physics, and Computer Science Faculty Articles and Research

We present an inexpensive architecture for converting a frequency-modulated continuous-wave LiDAR system into a compressive-sensing based depth-mapping camera. Instead of raster scanning to obtain depth-maps, compressive sensing is used to significantly reduce the number of measurements. Ideally, our approach requires two difference detectors. Due to the large flux entering the detectors, the signal amplification from heterodyne detection, and the effects of background subtraction from compressive sensing, the system can obtain higher signal-to-noise ratios over detector-array based schemes while scanning a scene faster than is possible through raster-scanning. Moreover, by efficiently storing only 2m data points from m < n measurements of an n pixel scene, we can easily extract depths by solving only two linear equations with efficient convex-optimization methods.