A source for quantum control: generation and measurement of attosecond ultraviolet light pulses

PDF Version Also Available for Download.

Description

This project has pursued the possibility of producing ultra-short pulses of coherent light using harmonic conversion of a mid-infrared light source, focused into an atomic gas medium. This was a joint effort with Louis DiMauro's experimental group at Brookhaven National Laboratory and in collaboration with Ken Schafer from Louisiana State University and Mette Gaarde from Lund University on the theoretical part. High order harmonic generation (HHG) in nobel gas media using short-pulse visible and near infrared lasers has become an established method for producing coherent, short pulse radiation at wavelengths from the ultraviolet to soft x-rays. We recently proposed that ... continued below

Physical Description

90 Kilobytes

Creation Information

Kulander, K C February 19, 1999.

Context

This report is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided by UNT Libraries Government Documents Department to Digital Library, a digital repository hosted by the UNT Libraries. More information about this report can be viewed below.

Who

People and organizations associated with either the creation of this report or its content.

Author

Sponsor

Publisher

Provided By

UNT Libraries Government Documents Department

Serving as both a federal and a state depository library, the UNT Libraries Government Documents Department maintains millions of items in a variety of formats. The department is a member of the FDLP Content Partnerships Program and an Affiliated Archive of the National Archives.

Contact Us

What

Descriptive information to help identify this report. Follow the links below to find similar items on the Digital Library.

Description

This project has pursued the possibility of producing ultra-short pulses of coherent light using harmonic conversion of a mid-infrared light source, focused into an atomic gas medium. This was a joint effort with Louis DiMauro's experimental group at Brookhaven National Laboratory and in collaboration with Ken Schafer from Louisiana State University and Mette Gaarde from Lund University on the theoretical part. High order harmonic generation (HHG) in nobel gas media using short-pulse visible and near infrared lasers has become an established method for producing coherent, short pulse radiation at wavelengths from the ultraviolet to soft x-rays. We recently proposed that this approach could lead to extremely short pulses, potentially less than one fs, provided the unavoidable frequency chirp of the highest harmonics, could be removed by compressing the pulses with a grating pair. Sources of sub-fs pulses would provide unique opportunities to study dynamical processes on time scales short compared to those associated with nuclear motion. Truly stroboscopic pictures of chemical reaction dynamics would be possible, for example. In this research project we have chosen much smaller driving frequencies than used previously in HHG studies for two reasons. First, this will allow us to measure the pulse lengths of the compressed harmonics because they will be in the vacuum ultraviolet where coincidence measurements are possible. Second, the wavelengths of these harmonics will be idea for pump-probe experiments of quantum dynamical control studies. Our theoretical effort was concentrated in two areas. We used our time-dependent quantum numerical codes to evaluate the harmonic response of alkali atoms to the mid-IR laser excitation. Results were obtained for potassium, the initial species to be used in the experiments, then sodium and rubidium to investigate the possibility of higher conversion efficiencies. In fact, rubidium was found to be significantly better than potassium, both because it provided a stronger harmonic response and because the target gas could be maintained at about an order of magnitude higher pressure than with potassium. The second theoretical focus was the development of an adiabatic approximation for solving the equations governing the propagation of the generated harmonic fields through the laser-excited medium. A code was constructed using this approximation and the first phase matching calculations in this ultra-short pulse regime were carried out. The experimental effort was slowed by difficulties with the potassium source which were solved and photoelectron and harmonic spectra were obtained, the first ever at these wavelengths. These preliminary experiments were carried out using a ps laser source and an estimate of the bandwidth of the harmonics was obtained. The spectral width indicated that our prediction that the harmonic pulse lengths can be two orders of magnitude shorter than the driving field appears probable. Soon the experiments will switch to a 100 fs driver and the attempt to reach the sub-fs regime will then be possible. W e found that potassium, the target in the initial studies had a lower than expected conversion efficiency so that experiments were initiated using rubidium. This has proved to be better by more than three orders of magnitude. A large fraction of this improvement was due to the metal source running at a much higher pressure. A further increase will be obtained when the shorter pulse driver is installed. An additional paper on these preliminary results is now being prepared. The project was quite successful, although a bit behind schedule because of experimental problems. The theoretical predictions seem to have been corroborated by the measurements thus far. We also found some unexpected differences in the behavior of the different alkali atoms to mulitphoton excitation and ionization at these wavelengths.

Physical Description

90 Kilobytes

Subjects

Language

Item Type

Identifier

Unique identifying numbers for this report in the Digital Library or other systems.

  • Other: DE00008201
  • Report No.: UCRL-ID-133244
  • Grant Number: W-7405-Eng-48
  • DOI: 10.2172/8201 | External Link
  • Office of Scientific & Technical Information Report Number: 8201
  • Archival Resource Key: ark:/67531/metadc739115

Collections

This report is part of the following collection of related materials.

Office of Scientific & Technical Information Technical Reports

Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

Office of Scientific and Technical Information (OSTI) is the Department of Energy (DOE) office that collects, preserves, and disseminates DOE-sponsored research and development (R&D) results that are the outcomes of R&D projects or other funded activities at DOE labs and facilities nationwide and grantees at universities and other institutions.

What responsibilities do I have when using this report?

When

Dates and time periods associated with this report.

Creation Date

  • February 19, 1999

Added to The UNT Digital Library

  • Oct. 18, 2015, 6:40 p.m.

Description Last Updated

  • Feb. 24, 2016, 1:21 p.m.

Usage Statistics

When was this report last used?

Yesterday: 0
Past 30 days: 0
Total Uses: 2

Interact With This Report

Here are some suggestions for what to do next.

Start Reading

PDF Version Also Available for Download.

International Image Interoperability Framework

IIF Logo

We support the IIIF Presentation API

Kulander, K C. A source for quantum control: generation and measurement of attosecond ultraviolet light pulses, report, February 19, 1999; Livermore, California. (digital.library.unt.edu/ark:/67531/metadc739115/: accessed May 27, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.