  We study the SL(2,R) WZWN string model describing bosonic string theory in
AdS_3 space-time as a deformed oscillator together with its mass spectrum and
the string modified SL(2,R) uncertainty relation. The SL(2,R) string oscillator
is far more quantum (with higher quantum uncertainty) and more excited than the
non deformed one. This is accompassed by the highly excited string mass
spectrum which is drastically changed with respect to the low excited one. The
highly excited quantum string regime and the low excited semiclassical regime
of the SL(2,R) string model are described and shown to be the quantum-classical
dual of each other in the precise sense of the usual classical-quantum duality.
This classical-quantum realization is not assumed nor conjectured. The quantum
regime (high curvature) displays a modified Heisenberg's uncertainty relation,
while the classical (low curvature) regime has the usual quantum mechanics
uncertainty principle.
