Time resolved reflectivity of bismuth thin film evaporated on a silicon substrate is measured by an 80 femtosecond (fs) laser at a center wavelength of 800 nm. The reflectivity data reveal that coherent optical phonons (A1g) near 2.9 THz (1 THz = 1012 Hz) are excited by the 80 fs laser pulses. Analyses of the reflectivity data reveal key parameters related to electron and phonon dynamics, including phonon excitation and de-phasing and electron-phonon energy coupling. It is also found that the phonon frequency peaks are red-shifted and broadened at higher laser fluences.

1.
Garrett
G. A.
,
Albrecht
T. F.
,
Whitaker
J. F.
, and
Merlin
R.
,
1996
, “
Coherent THz Phonons Driven by Light Pulses and the Sb Problem: What is the Mechanism?
”,
Phys. Rev. Lett.
,
77
(
17)
, pp.
3661
3664
.
2.
Hunsche S., Wienecke K., Dekorsy T., and Kurz H., 1995, “Impulsive Softening of Coherent Phonons in Tellurium”, 75(9), pp. 1815–1818.
3.
Misochko
O. V.
,
Hase
M.
,
Ishioka
K.
, and
Kitajima
M.
,
2004
, “
Observation of an Amplitude Collapse and Revival of Chirped Coherent Phonons in Bismuth
”,
Phys. Rev. Lett.
,
92
(
19)
, pp.
197401
197401
.
4.
Hase
M.
,
Kitajimal
M.
,
Nakashima
S.
, and
Mizoguchi
K.
,
2002
, “
Dynamics of Coherent Anharmonic Phonons in Bismuth Using High Density Photoexcitation
”,
Phys. Rev. Lett.
,
88
(
6)
, pp.
067401
067401
5.
Cheng
T. K.
,
Vidal
J.
,
Zeiger
H. J.
,
Dresselhaus
G.
,
Dresselhaus
M. S.
, and
Ippen
E. P.
,
1991
, “
Mechanism for displacive excitation of coherent phonons in Sb, Bi, Te, and Ti2O3
”,
Appl. Phys. Lett.
,
59
(
16)
, pp.
1923
1925
.
6.
Tangney
P.
, and
Fahy
S.
,
2002
, “
Density-functional theory approach to ultrafast laser excitation of semiconductors: Application to the A1 phonon in tellurium
”,
Phys. Rev. B.
,
65
(
5)
, pp.
054302
054302
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