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Title: Frequency up-conversion and trapping of ultrashort laser pulses in semiconductor plasmas

Abstract

It is shown that the interaction of ultrashort laser pulses with nonstationary semiconductor plasmas can, under appropriate conditions, lead to a variety of interesting phenomena including controlled upshifting of the laser frequency leading to the possibility of tunable lasers in a wide range of frequencies, and trapping (nonpropagation) of a substantial part of the incident pulse.

Authors:
 [1];  [2];  [3]
  1. Univ. of Texas, Austin, TX (United States). Inst. for Fusion Studies|[Inst. of Physics, Tbilisi (Georgia). Dept. of Plasma Physics
  2. Univ. of Texas, Austin, TX (United States). Inst. for Fusion Studies
  3. Inst. of Plasma Physics and Laser Microfusion, Warsaw (Poland)
Publication Date:
Research Org.:
Univ. of Texas, Inst. for Fusion Studies, TX (United States)
Sponsoring Org.:
USDOE Office of Energy Research, Washington, DC (United States)
OSTI Identifier:
674819
Report Number(s):
DOE/ER/54346-828
ON: DE99000352; TRN: AHC29820%%274
DOE Contract Number:
FG03-96ER54346
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: Jul 1998
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING NOT INCLUDED IN OTHER CATEGORIES; LASERS; FREQUENCY CONVERTERS; LASER RADIATION; SOLID-STATE PLASMA; TUNING; SEMICONDUCTOR MATERIALS

Citation Formats

Berezhiani, V.I., Mahajan, S.M., and Miklaszewski, R. Frequency up-conversion and trapping of ultrashort laser pulses in semiconductor plasmas. United States: N. p., 1998. Web. doi:10.2172/674819.
Berezhiani, V.I., Mahajan, S.M., & Miklaszewski, R. Frequency up-conversion and trapping of ultrashort laser pulses in semiconductor plasmas. United States. doi:10.2172/674819.
Berezhiani, V.I., Mahajan, S.M., and Miklaszewski, R. Wed . "Frequency up-conversion and trapping of ultrashort laser pulses in semiconductor plasmas". United States. doi:10.2172/674819. https://www.osti.gov/servlets/purl/674819.
@article{osti_674819,
title = {Frequency up-conversion and trapping of ultrashort laser pulses in semiconductor plasmas},
author = {Berezhiani, V.I. and Mahajan, S.M. and Miklaszewski, R.},
abstractNote = {It is shown that the interaction of ultrashort laser pulses with nonstationary semiconductor plasmas can, under appropriate conditions, lead to a variety of interesting phenomena including controlled upshifting of the laser frequency leading to the possibility of tunable lasers in a wide range of frequencies, and trapping (nonpropagation) of a substantial part of the incident pulse.},
doi = {10.2172/674819},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Jul 01 00:00:00 EDT 1998},
month = {Wed Jul 01 00:00:00 EDT 1998}
}

Technical Report:

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  • The paper studies the frequency up-conversion process of a 10.6 micron laser in an AgGaS{sub 2} nonlinear crystal, and presents the results of calculating the phase matching angle, the phase matching acceptance angle, and the effective bandwidth of 10.6 micron light. Thus, the frequency conversion of 10.6 micron light to 0.967 micron light is realized. In the nonfocussing mode, the maximum power conversion efficiency is greater than 7%. The eta(theta) and eta(Ip) curves were measured; the optimal phase matching angle is 38 deg 50 min for type II. Multiple factors that affect conversion efficiency are analyzed; the major noise sourcesmore » of the upconversion system of an infrared detector are also analyzed.« less
  • A model of the plasma resistivity, or equivalently the electron-ion collision frequency {nu}, which can be used to describe absorption of ultrashort laser pulses in solid density plasmas has been constructed. Using kinetic theory based on a memory function formulation and a projection operator method, we have derived an analytical expression for {nu}, which is valid in strongly coupled plasmas, properly accounts for the laser frequency dependence, and can be applied to plasmas with different electron and ion temperatures.
  • The authors present results of experimental investigations of laser guiding in plasma channels. A new technique for plasma channel creation, the Ignitor-Heater scheme is proposed and experimentally tested in hydrogen and nitrogen. It makes use of two laser pulses. The Ignitor, an ultrashort (< 100 fs) laser pulse, is brought to a line focus using a cylindrical lens to ionize the gas. The Heater pulse (160 ps long) is used subsequently to heat the existing spark via inverse Bremsstrahlung. The hydrodynamic shock expansion creates a partially evacuated plasma channel with a density minimum on axis. Such a channel has propertiesmore » of an optical waveguide. This technique allows creation of plasma channels in low atomic number gases, such as hydrogen, which is of importance for guiding of highly intense laser pulses. The channel density was diagnosed with time resolved longitudinal interferometry. From these measurements the plasma temperature was inferred. The guiding properties of the channels were tested by injecting a > 5 {times} 10{sup 17} W/cm{sup 2}, 75 fs laser pulse.« less
  • Laser-material interaction of powerful (up to a terawatt) ultrashort (several picoseconds or shorter) laser pulses and laser-induced effects were investigated theoretically in this dissertation. Since the ultrashort laser pulse (USLP) duration time is much smaller than the characteristic time of the hydrodynamic expansion and thermal diffusion, the interaction occurs at a solid-like material density with most of the light energy absorbed in a thin surface layer. Powerful USLP creates hot, high-pressure plasma, which is quickly ejected without significant energy diffusion into the bulk of the material, Thus collateral damage is reduced. These and other features make USLPs attractive for amore » variety of applications. The purpose of this dissertation was development of the physical models and numerical tools for improvement of our understanding of the process and as an aid in optimization of the USLP applications. The study is concentrated on two types of materials - simple metals (materials like aluminum or copper) and wide-bandgap dielectrics (fused silica, water). First, key physical phenomena of the ultrashort light interaction with metals and the models needed to describe it are presented. Then, employing one-dimensional plasma hydrodynamics code enhanced with models for laser energy deposition and material properties at low and moderate temperatures, light absorption was self-consistently simulated as a function of laser wavelength, pulse energy and length, angle of incidence and polarization. Next, material response on time scales much longer than the pulse duration was studied using the hydrocode and analytical models. These studies include examination of evolution of the pressure pulses, effects of the shock waves, material ablation and removal and three-dimensional dynamics of the ablation plume. Investigation of the interaction with wide-bandgap dielectrics was stimulated by the experimental studies of the USLP surface ablation of water (water is a model of biological tissue) and laser-induced pressure waves. Simulations on the basis of the nonlinear ionization equation were used to examine effects of the laser created surface plasma on light absorption, reflection and transmission. Laser pulse energy conversion efficiency into pressure waves was studied experimentally and theoretically.« less