  We have investigated the optical properties of a single InAsP quantum dot
embedded in a standing InP nanowire. A regular array of nanowires was
fabricated by epitaxial growth and electron-beam patterning. The elongation of
transverse exciton spin relaxation time of the exciton state with decreasing
excitation power was observed by first-order photon correlation measurements.
This behavior is well explained by the motional narrowing mechanism induced by
Gaussian fluctuations of environmental charges in the InP nanowire. The
longitudinal exciton spin relaxation time was evaluated by the degree of the
random polarization of emission originating from exciton state confined in a
single nanowire quantum dots by using Mueller Calculus based on Stokes
parameters representation.
