Download Picosecond Phenomena: Proceedings of the First International Conference on Picosecond Phenomena. Hilton Head, South Carolina, USA, May 24–26, 1978 PDF

TitlePicosecond Phenomena: Proceedings of the First International Conference on Picosecond Phenomena. Hilton Head, South Carolina, USA, May 24–26, 1978
File Size14.2 MB
Total Pages369
Document Text Contents
Page 1

4 Springer Series in Chemical Physics Edited by Fritz Peter Schafer

Page 2

Springer Series in Chemical Physics
Editors: V. 1. Goldanskii R. Gomer F. P. Schafer J. P. Toennies

Volume 1 Atomic Spectra and Radiative Transitions
By I. I. Sobelman

Volume 2 Surface Crystallography by LEED, Theory, Computation,
and Structural Results
By M. A. Van Hove, S. Y. Tong

Volume 3 Advances in Laser Chemistry
Editor: A. H. Zewail

Volume 4 Picosecond Phenomena
Editors: C. V. Shank, E. P. Ippen, S. L. Shapiro

Volume 5 Laser Spectroscopy, Fundamentals and Techniques
By W. Demtr6der

Volume 6 Laser induced Processes in Molecules
Editors: K. Kompa, D. Smith

Page 184

v. Poster Session

Page 185

Picosecond Optical Absorption at 1.06 pm and 1.55 pm in Thin
Gennanium Samples at High Optically-Created Carrier Densities

A.L. Smirl, J.R. Lindle, and S.C. Moss
Department of Physics, North Texas State University
Denton, TX 76203, USA

Recently, the enhanced transmission of single, ultrashort optical pulses
at 1.06 ~m through germanium as a function of incident pulse energy has been
measured [1]. In addition, the temporal evolution of this enhanced transmis-
sion has been determined on a picosecond time scale using the excite and probe
technique [1,2]. The latter measurements reveal that the probe transmission
increases for 50-100 psec following excitation with an intense optical pulse.
ELCt et al. [3] have attributed this rise in the probe transmission to a cool-
ing o~the hot electron-hole plasma created by the excitation pulse. In sharp
contrast to this interpretation, AUSTON et al. [4] have stated that they ex-
pect the energy relaxation time to be toO-short to account for the rise in the
probe transmission. AUSTON et al. also suggest that enhanced free-hole [5]
and Coulomb-assisted indirec~absorption [6] effects can be significant at the
high optically-created carrier densities encountered in the excitation-probe
measurements at 1 .06 ~m. Indeed, they suggest that these processes could in-
troduce a minimum in the absorption versus carrier density relationship. AUS-
TON and MCAFEE [7] have proposed an alternative explanation for the temporal
evolution of the probe transmission by combining the details of the way the
absorption saturates as a function of carrier density with a monotonic de-
crease in carrier density with time due to Auger recombination [8]. The rise
in probe transmission with time can then be explained in the following manner.
We denote the density at which the minimum absorption occurs as nmin. The
absorption of the excitation pulse creates an initial carrier density greater
than nmin' As the carrier density is decreased by Auger recombination, the
absorption coefficient will decrease in time until the carrier density reaches
nmin, then increase. Thus, the probe transmission will increase then decrease
if the initial, optically-created carrier density is greater than nmin. We
stress that the success of the second model as it now stands depends on the
absorption decreasing then increasing with carrier density: there must be an
absorption minimum. ------

Here, we report measurements of the combined free-carrier, intervalence
band free-hole, and indirect absorbance in thin germanium samples at a wave-
length of 1 .55 ~m during excite and probe experiments at a wavelength of 1.06
~m. Our interests in these measurements are twofold. First, we want to as-
certain whether or not free-carrier, free-hole, and indirect absorption ef-
fects are important in excite-probe experiments at 1 .06 ~m. Second, if these
effects are important, can they, together with Auger effects, account for the
rise in probe transmission.

The experimental configuration is depicted in Fig.l. This arrangement is
similar to the arrangement util ized by AUSTON et al. [8]. In this appl ication
of the excite and probe technique, a high density-Plasma is created by direct


Page 368


Founded by H. K V. Lotsch

New York

Volume 18

Utrashort Light Pulses
Editor: S. L. Shapiro

1977. 173 figures. XI, 389 pages
ISBN 3-540-08103-8

With the advent of picosecond light pulses a decade ago
numerous scientists recognized that new methods of prime
importance for exploring molecular interactions were feasible
and also that extremely rapid devices based on new principles
were possible. Now that the basic fundamentals of picosecond
technology are well understood, and many of the early explora-
tion goals have been realized, it is important to present the first
comprehensive treatment by distinguished experts on both
pulse generation and pulse interactions with matter. Like the
spectroscopy field (where phenomena are understood through
measurements in the frequency domain), the picosecond pulse
field (where phenomena are analyzed in the time domain) is
here to stay. The book aims to summarize the state ofthe art
now that picosecond technology is rapidly emerging as a general
tool in many different disciplines. Students and professionals
in the sciences and engineering will be fascinated by the new
developments and will profit from understanding these new
general techniques.

S.L.Shapiro: Introduction - A Historical Overview.
D. J. Bradley: Methods of Generation. E. P. Ippen, C. V. Shank:
Techniques for Measurement. D.H.Auston: Picosecond Non-
linear Optics. D. von der Linde: Picosecond Interactions in
Liquids and Solids. K.B.Eisenthal: Picosecond Relaxation
Processes in Chemistry. A. J. Campillo, S. L. Shapiro: Pico-
second Relaxation Measurements in Biology.

Volume 13

Laser Spectroscopy
Editor: K Shimoda

1976. 132 figures. XIII, 378 pages
ISBN 3-540-07719-7

K. Shimoda: Introduction. K. Shimoda: Line Broadening and
Narrowing Effects. P. Jacquinot: Atomic Beam Spectroscopy.
V. S. Letokhov: Saturation Spectroscopy. J. L. Hall,
J.A. Magyar: High Resolution Saturated Absorption Studies of
Methane and Some Methyl-Halides. V.D.Chebotayev: Three-
Level Laser Spectroscopy. S.Haroche: Quantum Beats and
TIme-Resolved Fluorescence Spectroscopy. N.Bloembergen,
M. D.Levenson: Doppler-Free Two-Photon Absorption

Page 369


Editor: D. L. MacAdam

Volume 3:

Tunable Lasers and Applications
Proceedings ofthe Loen Conference, Norway, 1976
Editors: A Mooradian, T. Jaeger, P. Stokseth

1976.238 figures. VIII, 404 pages
ISBN 3-540-07968-8

Volume 4
V. S. Letokhov, V. P. Chebotayev

Nonlinear Laser Spectroscopy
1977. 193 figures, 22 tables. XVI, 466 pages
ISBN 3-540-08044-9

Volume 6

Photoelectron Statistics
With Applications to Spectroscopy and Optical

1978.85 figures, 8 tables. XV, 441 pages
ISBN 3-540-08295-6

Volume 7

Laser Spectroscopy III
Proceedings of the Third International Conference,
Jackson Lake Lodge, Wyoming, USA,
July 4-8, 1977

Berlin Editors: 1. L. Hall, 1. L. Carlsten
Heidelberg 1977.296 figures. XII, 468 pages
New York ISBN 3-540-08543-2

Similer Documents