Organizational Unit:

School of Physics

Permanent Link

https://hdl.handle.net/1853/70755

Parent Organization

Organizational Unit

College of Sciences

Includes Organization(s)

Organizational Unit

Center for Relativistic Astrophysics

Organizational Unit

Mourigal Lab

ArchiveSpace Name Record

https://finding-aids.library.gatech.edu/agents/corporate_entities/156

Full item page

Publication Search Results

Now showing 1 - 10 of 20

On-shot Spatiotemporal Laser Wavefront Characterization via Wavelength-Multiplexed Holography for Precision Control of High-Intensity Laser Plasma Interactions

(Georgia Institute of Technology, 2022-04-14) Grace, Elizabeth S.

Short-pulse (<10 ps), high-intensity (>10^18 W/cm^2) laser systems can be used to generate and probe extremely high energy and density conditions of matter. The plasmas produced by these high intensity laser systems can act as compact radiation sources, can emulate astrophysical phenomena like supernova and centers of giant planets, and even allow access to fusion regimes. Besides fundamental plasma physics, these ultraintense laser-matter interactions also lend themselves to impactful scientific applications, including renewable energy and state-of-the-art medical techniques. A continuing fundamental need in the field of laser-driven High Energy Density (HED) and plasma physics is the accurate and precise spatial and temporal characterization of the laser pulse, which would provide valuable insight into the foundational physics that drive these interactions. Laser-plasma interactions are complex, rapidly evolving, and highly sensitive to shot-to-shot variations in laser parameters, such as laser peak intensity, pulse duration, pre-pulse, and focal spot, and/or thermal instabilities. Even under nominally identical laser conditions, small variations can drastically influence outcomes. However, in typical HED experiments currently, the complexity of the 4-D laser electric field E(x,y,z,t) can mean that the wavefront is not often characterized, or that it is characterized in a surrogate shot. This thesis discusses the development of a single-frame laser characterization diagnostic for novel use on high-intensity, low repetition rate laser systems, its adaptation to high-repetition rate (>Hz) laser systems, its use in diagnosing and optimizing an ultraintense laser system, and its role in developing a more complete understanding of the underlying laser-plasma interaction physics. Breakthroughs in these measurement capabilities can unlock an entirely new regime of experimental measurement, deliver a novel capacity to determine and assess pivotal factors that limit more precise control of laser-driven radiation sources, and serve as a necessary tool to improve laser-plasma interaction predictive capability.
COMPLETE TEMPORAL MEASUREMENT OF LOW-INTENSITY AND HIGH-FREQUENCY ULTRASHORT LASER PULSES

(Georgia Institute of Technology, 2020-12-08) Jones, Travis N.

Two important frontiers in the field of ultrashort pulse measurement are the complete temporal measurement of low-intensity picosecond pulses in the near-infrared (NIR) and intense ultrashort pulses in the ultraviolet (UV) and extreme ultraviolet (EUV). The former are projected to find great use in the field of optical telecommunications, while the latter are the result of the relatively recent development of bright, coherent light sources in this wavelength range. The challenge in measuring weak pulses in the NIR is that many measurement techniques require expensive electronics and/or are complicated and difficult to align. UV pulse measurement on the other hand, due to the higher photon energies involved, is primarily hindered by slow light-matter interactions such as absorption or photoionization. In this thesis, we develop and present two novel pulse-measurement techniques based on the widely-used method of Frequency-Resolved Optical Gating (FROG) which are aimed at addressing these challenges. The first technique, called Collinear GRENOUILLE, is an experimentally-simple and sensitive device which tests the sensitivity of second harmonic generation to measure low-intensity, picosecond pulses in the NIR. The measurement capabilities of Collinear GRENOUILLE are experimentally demonstrated by the successful measurement moderately complex pulses with femtojoule pulse energies at 800 nm. A similar measurement is also presented at 1030 nm where more efficient nonlinear crystals exist. The second technique, known as Induced-Grating Cross-correlation FROG, is designed to measure intense laser pulses in the UV and EUV. To demonstrate this technique, we first perform measurements of chirped 400 nm pulses in a fast-responding nonlinear medium. We show that the resulting traces contain the complete electric field of the UV pulse we intended to measure. We further confirm these measurement by developing a modified phase-retrieval algorithm to reconstruct the pulse from the measured traces. Next, we performed similar measurements in a slowly-responding medium. FROG typically requires a fast nonlinear-optical processes to measure pulses, however once the response of the medium in accounted for, the measurements made using the IG XFROG technique indicate that accurate measurements of the pulse can still be made using a slow light-matter interaction. In the case of slow media, the IG XFROG technique is first demonstrated using absorption from amplified pulses at 400 nm and 267 nm. After establishing feasibility at these wavelengths, we applied this technique to EUV laser pulses from the FERMI free-electron laser at 31.3 nm, for which the dominant light-matter interaction is photoionization.
Reliable Pulse-Retrieval for Frequency-Resolved-Optical-Gating

(Georgia Institute of Technology, 2020-08-19) Jafari, Rana

Frequency-resolved-optical-gating (FROG) measures the full temporal information of arbitrary ultrashort laser pulses' fields using two-dimensional data in the time-frequency domain. By benefiting from the properties of the acquired 2D data, FROG not only measures stable pulses accurately, but also it indicates the presence of pulse-shape instability in the pulse train by a discrepancy between the measured and retrieved FROG traces using its pulse-retrieval algorithm. However, this discrepancy could also arise when the pulse-retrieval algorithm stagnates. When the current best algorithm, generalized projections (which is known to stagnate as much as half the time) is used to retrieve the field from a trace of unstable pulse trains, the retrieved fields may vary significantly from one retrieval to the other, while never returning a pulse that matches the measured trace. So, it is difficult to distinguish the presence of instability from the stagnation of the algorithm. In this dissertation, the Retrieved-Amplitude N-grid Algorithmic (RANA) approach is introduced for the 100% reliable pulse-retrieval from FROG traces of stable pulses with even high complexities and significant noise for the commonly used FROG geometries. Further, the performance of the RANA approach for traces contaminated with artifacts due to averaging over a pulse train with unstable pulse shapes is investigated. The results indicate that the RANA approach returns pulses that yield the lowest achievable discrepancy between the measured and retrieved traces for the traces of unstable trains. Thus RANA approach convincingly indicates the stability or instability of the pulse train, solving the problem. It also yields the correct approximate pulse length, spectral width, and time-bandwidth product, including some structure when present.
Single-frame complete spatiotemporal measurement of complex ultrashort laser pulses

(Georgia Institute of Technology, 2016-04-01) Guang, Zhe

Today one of the frontiers in light measurement is to measure ultrashort pulses from ultrafast laser systems, which demonstrate extremely fast temporal variations, and are necessarily associated with large spectral bandwidths by Fourier transform. In addition to the temporal and spectral structures, ultrashort pulses can also be complex in space. Especially, the field can have spatiotemporal couplings which relate pulse temporal profile to spatial coordinates. Therefore, a complete spatiotemporal measurement technique is needed. In this work, we demonstrate our study on measuring complex ultrashort pulses by development of a method, called Spatially and Temporally Resolved Intensity and Phase Evaluation Device: Full Information from a Single Hologram (STRIPED FISH). Based on digital holography, this simple single-frame method can measure the complete spatiotemporal intensity I(x,y,t) and phase ϕ(x,y,t) of pulses at a particular z-plane. By experiments, we investigated sub-picosecond chirped pulse beating, pulses from multimode optical fibers, ultrafast lighthouse effect and so on, using STRIPED FISH. We also performed numerical simulations to understand the effects of different spatiotemporal distortions on STRIPED FISH trace. With its improved apparatus, processing algorithm, and display method, STRIPED FISH offers a simple and compact solution to monitor, measure, and display spatiotemporal structures in ultrashort pulses.
Troubleshooting ultrashort pulse measurement: the coherent artifact and other issues

(Georgia Institute of Technology, 2016-03-14) Rhodes, Michelle Ann

Theoretical limitations of several ultrashort pulse measurement techniques are investigated. Particular attention is paid to the consequences of averaging over many pulses of different shapes. Averaging over many pulses is a very common practice, and if the pulse shape varies then the measurement result will be incorrect. This issue, referred to as a coherent artifact, is simulated for frequency-resolved optical gating using several nonlinearities, spectral interferometry for direct electric field reconstruction, two-dimensional spectral shearing interferometry, self-referenced spectral interferometry using cross-polarized wave generation, and multiphoton intrapulse interference phase scan. The role of measurement feedback in identifying pulse-shape instability is explored where possible. Several techniques receive additional analysis, such as searching for ambiguities or simulating convergence conditions. In addition, a method for intuitively displaying spatiotemporally distorted pulses is explored and developed.
Single-shot measurements of complex pulses using frequency-resolved optical gating

(Georgia Institute of Technology, 2013-11-07) Wong, Tsz Chun

Frequency-resolved optical gating (FROG) is the standard for measuring femtosecond laser pulses. It measures relatively simple pulses on a single-shot and complex pulses using multi-shot scanning and averaging. However, experience from intensity autocorrelation suggests that multi-shot measurements may suffer from a coherent artifact caused by instability in the laser source. In this thesis, the coherent artifacts present in modern pulse measurement techniques are examined and single-shot techniques for measuring complex pulse(s) are proposed and demonstrated. The study of the coherent artifact in this work shows that modern pulse measurement techniques also suffer from coherent artifacts and therefore single-shot measurements should be performed when possible. Here, two single-shot experimental setups are developed for different scenarios. First, an extension of FROG is developed to measure two unknown pulses simultaneously on a single-shot. This setup can measure pulses that have very different center wavelengths, spectral bandwidths, and complexities. Second, pulse-front tilt is incorporated to extend the temporal range of single-shot FROG to tens of picoseconds which traditionally can only be attained by multi-shot scanning. Finally, the pulse-front tilt setup is modified to perform a single-shot measurement of supercontinuum, one of the most difficult pulses to measure due to its long temporal range, broad spectral bandwidth, and low pulse energy.
Optical-parametric-amplification applications to complex images

(Georgia Institute of Technology, 2011-07-01) Vaughan, Peter Matthias

We have used ultrafast optics, primarily focused on the nonlinear processes of Polarization Gating and of Optical Parametric Amplification, one for measurement and the other for imaging purposes. For measurement, we have demonstrated a robust method of measurement to simultaneously measure both optical pulses used in a pump-probe type configuration. We refer to this method of pulse measurement as Double Blind Polarization Gating FROG. We have demonstrated this single-shot method for measuring two unknown pulses using one device. In addition to pulse measurement, we have demonstrated the processes of Optical Parametric Amplification (OPA) applicability to imaging of complex objects. We have done this where the Fourier transform plane is used during the interaction. We have amplified and wavelength converted a complex image. We observe a gain of ~100, and, although our images were averaged over many shots, we used a single-shot geometry, capable of true single-shot OPA imaging. To our knowledge, this is the first Fourier-plane OPA imaging of more than a single spatial-frequency component of an image. We observe more than 30 distinct spatial frequency components in both our amplified image and our wavelength shifted image. We have demonstrated all-optical spatial filtering for these complex images. We have demonstrated that direct Fourier filtering of spatial features is possible by using a shaped pump beam. We can isolate certain portions of the image simply by rotating the crystal.
Pulse compression and dispersion control in ultrafast optics

(Georgia Institute of Technology, 2011-01-22) Chauhan, Vikrant Chauhan Kumar

Pulse Compression and Dispersion Control in Ultrafast Optics Vikrant K. Chauhan 116 Pages Directed by Dr. Rick P. Trebino In this thesis, we introduced novel pulse compressors that are easy to align and which also compensate for higher order dispersion terms. They use a single dispersive element or a combination of dispersive elements in single-element-geometry. They solve the problem of extra-cavity pulse compression by providing control of the pulse width in almost all of the experiments performed using ultrashort pulses, and they even compensate for higher order dispersion. We performed full spatiotemporal characterization of these compressors and demonstrated their performance. We also developed a theoretical simulation of pulse compressors which is based on a matrix based formalism. It models the full spatiotemporal characteristics of any dispersion control system. We also introduced a simple equation, in its most general form, to relate the total dispersion and magnification introduced by an arbitrary sequence of dispersive devices. Pulse compressor characterization was done using interferometric measurements in the experiments presented in this work, but we also developed a method to measure pulses that uses polarization gating FROG for measuring two unknown pulses. In the last part, we briefly discuss the designing of a high energy chirped pulse amplification system.
Measuring the electric field of picosecond to nanosecond pulses with high spectral resolution and high temporal resolution

(Georgia Institute of Technology, 2010-10-08) Cohen, Jacob Arthur

We demonstrate four experimentally simple methods for measuring very complex ultrashort light pulses. Although each method is comprised of only a few optical elements, they permit the measurement of extremely complex pulses with time-bandwidth products greater than 65,000. First, we demonstrate an extremely simple frequency-resolved-optical gating (GRENOUILLE) device for measuring the intensity and phase of pulses up to ~20ps in length. In order to achieve the required high spectral resolution and large temporal range, it uses a few-cm-thick second harmonic-generation crystal in the shape of a pentagon. This has the additional advantage of reducing the device's total number of components to three. Secondly, we introduce a variation of spectral interferometry (SI) using a virtually imaged phased array and grating spectrometer for measuring long complex ultrashort pulses up to 80 ps in length. Next, we introduce a SI technique for measuring the complete intensity and phase of relatively long and very complex ultrashort pulses. It involves making multiple measurements using SI (in its SEA TADPOLE variation) at numerous delays, measuring many temporal pulselets within the pulse, and concatenating the resulting pulselets. Its spectral resolution is the inverse delay range--many times higher than that of the spectrometer used. The waveforms were measured with ~ fs temporal resolution over a temporal range of ~ns and had time-bandwidth products exceeding 65,000, which to our knowledge is the largest time-bandwidth product ever measured with ~fs temporal resolution. Finally, we demonstrate a single-shot measurement technique that temporally interleaves hundreds of measurements with ~fs temporal resolution. It is another variation of SI for measuring the complete intensity and phase of relatively long and complex ultrashort pulses in a single shot. It uses a grating to introduce a transverse time delay into a reference pulse which gates the unknown pulse by interfering it at the image plane of an imaging spectrometer. It provided ~125 fs temporal resolution and a temporal range of 70 ps using a low-resolution spectrometer.
Measurement of complex ultrashort laser pulses using frequency-resolved optical gating

(Georgia Institute of Technology, 2009-07-06) Xu, Lina

This thesis contains three components of research: a detailed study of the performance of Frequency-Resolved Optical Gating (FROG) for measuring complex ultrashort laser pulses, a new method for measuring the arbitrary polarization state of an ultrashort laser pulse using Tomographic Ultrafast Retrieval of Transverse Light E-fields (TURTLE) technique, and new approach for measuring two complex pulses simultaneously using PG blind FROG. In this thesis, we compare the performance of three versions of FROG to measure complex ultrashort laser pulses: second-harmonic-generation (SHG) FROG, polarization-gate (PG) FROG, and cross-correlation FROG (XFROG). We found that the XFROG algorithm achieves 100% convergence, while PG FROG and SHG FROG GP algorithm achieve 100% convergence after doing the noise deduction and increasing the sampling range. The second part of this thesis describes a method for measuring the intensity, phase and the complete polarization state of a laser pulse having a time-dependent polarization state (i.e. a polarization shaped pulse). This technique is called tomographic ultrafast retrieval of transverse light E-fields (TURTLE). TURTLE typically involves making three FROG measurements: one of the intensity and phase of the pulse's horizontal polarization component, one of its vertical component, and another of the 45o component. Performing a simple minimization using these three FROG measurements, the time-dependent polarization state of the ultrashort pulse can be determined. The third part of this thesis introduces a method for measuring two complex pulses simultaneously using a single FROG device. This technique is based on Polarization-gate (PG) FROG and it is called PG blind FROG. It involves two measurements: One of them is a PG FROG trace using the intensity of pulse 1 to gate pulse 2 and other one is the PG FROG trace using the intensity of pulse 2 to gate pulse 1. An iterative phase retrieval algorithm based on generalized projection (GP) is used to reconstruct the intensity and phase of these two pulses. This approach is an elegant way to measure complex and/or very spectrally broad pulses such as those due to super continuum.