A5023778734- Advanced Fiber Laser Technologies
- Laser-Matter Interactions and Applications
- Laser Material Processing Techniques
- Laser-induced spectroscopy and plasma
- Solid State Laser Technologies
- Nonlinear Optical Materials Studies
- Photonic Crystal and Fiber Optics
- Orbital Angular Momentum in Optics
- Diamond and Carbon-based Materials Research
- Integrated Circuits and Semiconductor Failure Analysis
- Radio Astronomy Observations and Technology
- Advanced Fiber Optic Sensors
- Photonic Crystals and Applications
- Ga2O3 and related materials
- GaN-based semiconductor devices and materials
- Optical Coatings and Gratings
- Phase-change materials and chalcogenides
- Superconducting and THz Device Technology
- Radiation Detection and Scintillator Technologies
- Strong Light-Matter Interactions
- Particle Accelerators and Free-Electron Lasers
- Atomic and Subatomic Physics Research
- Advanced Surface Polishing Techniques
- Particle Detector Development and Performance
- Transition Metal Oxide Nanomaterials
The Ohio State University
2019-2023
Hillsdale College
2020-2023
United States Air Force Research Laboratory
2019-2021
DEVCOM Army Research Laboratory
2021
ORCID
2020
Wright-Patterson Air Force Base
2019
University of Notre Dame
2012
We present time-of-arrival (TOA) measurements and timing models of 47 millisecond pulsars (MSPs) observed from 2004 to 2017 at the Arecibo Observatory Green Bank Telescope by North American Nanohertz for Gravitational Waves (NANOGrav). The observing cadence was three four weeks most over this time span, with weekly observations six sources. These data were collected use in low-frequency gravitational wave searches other astrophysical purposes. detail our observational methods a set TOA...
Abstract Femtosecond-laser-assisted material restructuring employs extreme optical intensities to localize the ablation regions. To overcome minimum feature size limit set by wave nature of photons, there is a need for new approaches tailored processing at nanoscale. Here, we report formation deeply-subwavelength features in silicon, enabled localized laser-induced phase explosions prefabricated silicon resonators. Using short trains mid-infrared laser pulses, demonstrate controllable high...
We present a new analysis of the profile data from 47 millisecond pulsars comprising 12.5-year set North American Nanohertz Observatory for Gravitational Waves (NANOGrav), which is presented in parallel paper (Alam et al. 2021a; NG12.5). Our reprocessing performed using "wideband" timing methods, use frequency-dependent template profiles, simultaneous time-of-arrival (TOA) and dispersion measure (DM) measurements broadband observations, novel techniques. In particular, wideband DM are used...
The importance of high intensity few- to single-cycle laser pulses for applications such as intense isolated attosecond pulse generation is constantly growing, and with the breakdown monochromatic approximation in field ionization models, few-cycle (FCP) interaction solids near damage threshold has ushered a new paradigm nonperturbative light-matter interaction. In this Letter, we systematically study contrast how femtosecond laser-induced ablation behaviors SiO2/HfO2-based reflective...
High peak and average power lasers with high wall-plug efficiency, like the Big Aperture Thulium (BAT) laser, have garnered tremendous attention in laser technology. To meet requirements of BAT we developed low-dispersion reflection multilayer dielectric (MLD) gratings suitable for compression high-energy pulses operations at 2 micron wavelength. We carried out 10000-on-1 damage tests to investigate fluence thresholds designed MLD mirrors, which were found between 100-230 mJ/cm2. An...
Polycrystalline materials can mediate efficient frequency up-conversion for mid-infrared light. Motivated by the need to understand properties of harmonic and supercontinuum radiation from such media, we utilize realistic numerical simulations reveal its complex temporal spatial structure. We show that generated propagates in form long-duration pulse trains be difficult compress optical filamentation high-energy pulses gives rise fine-structured beam profiles. identify trends concerning...
High harmonic generation (HHG) opens a window on the fundamental science of strong-field light-mater interaction and serves as key building block for attosecond optics metrology. Resonantly enhanced HHG from hot spots in nanostructures is an attractive route to overcoming well-known limitations gases bulk solids. We demonstrate nanoscale platform highly efficient driven by strong mid-infrared laser pulses: ultra-thin resonant gallium phosphide (GaP) metasurface. The wide bandgap lack...
Both gallium oxide and nitride have great potential for use as high power transparent conducting materials a wide range of optoelectronic applications. It is, therefore, important to determine the dynamic optical field breakdown these materials. Here, we report laser damage thresholds Ga2O3 GaN using 9 fs few-cycle pulses with center wavelength near 760 nm. We laser-induced (LIDTs) both single pulse multi-pulse exposures, LIDT showing significant reduction compared (in some cases,...
Abstract High harmonic generation (HHG) opens a window on the fundamental science of strong-field light-mater interaction and serves as key building block for attosecond optics metrology. Resonantly enhanced HHG from hot spots in nanostructures is an attractive route to overcoming well-known limitations gases bulk solids. We demonstrate nanoscale platform highly efficient driven by strong mid-infrared laser pulses: ultra-thin resonant gallium phosphide (GaP) metasurface. The wide bandgap...
Internet-of-things (IoT) objects are expected to exceed 75 billion by 2020, and a large part of the expansion is be at finer granularity than existing silicon-based IoT (i.e. tablets cell phones) can deliver [1]. Currently, placing room light or thermostat on internet for remote control considered progressive. However, if printed electronics achieve performance increases, then could affixed almost anything, such as coffee creamer cartons, cereal boxes, that missing sock. Each these driving...
The pulse duration dependence of single-shot laser-induced damage and ablation HfO<sub>2</sub>/SiO<sub>2</sub>-based double- quadlayer thin films is studied using time-resolved surface microscopy (TRSM) ex situ imaging down to the few-cycle (FCP) regime. Both samples exhibit a raised, "blister" morphology for range fluences between thresholds. fluence associated with blister formation much larger FCPs than 110 fs pulses, TRSM images at early time-delays show that density laser-generated...
We investigate the nonlinear optical properties of ZnSe and ZnS using ultrashort (pulse duration approximately 200 fs) midwave infrared laser pulses between 3 4 μm. Multiple harmonic generation in both materials was observed, as well significant spectral modification fundamental pulse. Simulations a polarization model enhanced with ionization compared favorably experimental data. Random quasi phase matching is likely generator observed harmonics.
Nonlinear refraction coefficients are measured via the Z-scan technique in mid-infrared spectral region for infrared transmitting materials. Harmonic and supercontinuum generation modeled using experimentally obtained values compared to experimental observations.
Single crystal fibers doped with Er or Tm and clad a sapphire sol-gel were tested for both laser performance super-continuum generation. Laser was explored multiple cladding deposition cycles (0 to 5) in addition variable concentration (0.25% 3%). A single sample showed exemplary (2% 3 cycles) achieving 44.5% slope-efficiency. Super-continuum generation compared pure of 150μm 50μm diameters at five different pump wavelengths an 80 fs source. generated covering 1.5 octaves (790 nm pump) <2.5...
This work seeks to explore the interplay between material differences in nonlinear index of refraction <i>n</i><sub>2</sub> and zero group velocity dispersion wavelength λ<sub>GVD</sub> formation spectral broadening supercontinuum generation. We present mid-wave infrared (MWIR) spectroscopic data transmitted 200 fs (FWHM) laser pulse through polycrystalline zinc selenide sulfide (Cleartran™) optical materials. Using MWIR wavelengths 3.3 3.8 μm, we vary energy roughly 1 126 μJ...
Many optical metrology applications require light that is both coherent and broadband. Supercontinuum (SC) spanning several wavelength octaves an obvious candidate for such applications. Optical fibers are a natural platform SC generation due to the long interaction length of within fiber which allows broad can ultimately be used as tunable narrowband source. For tunability in mid-IR regime, YAG excellent their high transparency, Kerr nonlinearity, damage threshold. In our work, we study...
We focus intense, ultrashort, 3.6 micron-wavelength pulses into three single-crystal zincblende chalcogenide samples, ZnS(100), ZnS(110), and ZnSe(100). Symmetry properties of the generated harmonics are studied by rotating crystals measuring output polarization.
Few-cycle pulse laser damage and ablation of HfO2/SiO2-based single-, double-, quad-layer thin films are studied using time-resolved surface microscopy. Ablation multilayer samples happens as fast for the single-layer, indicating a "blow-out" mechanism.
Using intense 3.6 μm, 200 fs, 500 Hz laser pulses, non-linear spectral broadening, filamentation and 2nd-9th harmonic generation in ZnS (Cleartran™) with 3-40 mm propagation distance were observed. Non-linear index of Cleartran was also measured.
Yttrium aluminum garnet (YAG) is a common host material for both bulk and single-crystal fiber lasers. With increasing interest in developing optical technologies the short-wave infrared mid-infrared wavelength range, YAG may be potential supercontinuum medium these applications. Here, we characterize femtosecond laser pumped generation with 1200–2000 nm pump wavelengths ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub>...
Abstract Femtosecond-laser-assisted material restructuring employs extreme optical intensities to localize the ablation regions. To overcome minimum feature size limit set by wave nature of photons, there is a need for new approaches tailored processing at nanoscale. Here, we report formation deeply-subwavelength features in silicon, enabled localized laser-induced phase explosions pre-fabricated silicon resonators. Using short trains mid-infrared laser pulses, demonstrate controllable high...
In our recent experiment, it is discovered that the interaction of resonant metasurfaces and mid-infrared femtosecond laser pulses can realize damage patterns overcome this limitation, geometry trench be controlled by pulse intensity, polarization, total number. study, we report particle-in-cell (PIC) simulation M-shape metasurface 200-fs mid-IR with high intensity. The results suggest localized lattice heating explosions occur at a scale in relationship polarization consistent experimental data.
We have been studying ways in which the light from several optical fibers that transmit scintillating tiles can be mixed and combined a single Silicon Photo Multiplier (SiPM). The purpose for mixing is to prevent high intensity fiber saturating an area of SiPM thus causing inaccurate reading overall collected. In particular this use detectors such as CMS HCAL <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1, 2</sup> where transmitted 940µm...
We develop a modification of the Z-scan technique that simultaneously measures nonlinear refraction and absorption while using single detector. This utilizes quadrant cell detector to measure both change in spot size due optical nonlinearity without use partially closed aperture or second improves ease alignment, requires half detectors all available beam power. is especially useful at IR wavelengths, where alignment can be difficult responsivities are low limiting signal noise.
Using intense $3.6 \mu \mathrm{m}$ , 200 fs, 500 Hz laser pulses, non-linear spectral broadening, filamentation and 2nd-9th harmonic generation in ZnS (Cleartran™) with 3–40 mm propagation distance were observed. Non-linear index of Cleartran was also measured. © 2019 The Author(s)