We have simultaneously excited a coherent and a squeezed phonon field in
SrTiO3 using femtosecond laser pulses and stimulated Raman
scattering. The frequency of the coherent state (~ 1.3 THz) is that
of the A
1g-component of the soft mode responsible
for the cubic-tetragonal phase transformation at ≈ 110 K. The
squeezed field involves a continuum of transverse acoustic phonons dominated by
a narrow peak in the density of states at ~ 6.9 THz.
© Optical Society of America
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