  We study the flight time fluctuations in an anisotropic medium inspired by a
cosmic string with an effective fluctuating refractive index caused by
fluctuating vacuum electric fields, which are analogous to the lightcone
fluctuations due to fluctuating spacetime metric when gravity is quantized. The
medium can be realized as a metamaterial that mimics a cosmic string in the
sense of transformation optics. For a probe light close to the analogue string,
the flight time variance is $\nu$ times that in a normal homogeneous and
isotropic medium, where $\nu$ is a parameter characterizing the deficit angle
of the spacetime of a cosmic string. The parameter $\nu$, which is always
greater than unity for a real cosmic string, is determined by the dielectric
properties of the metamaterial for an analogue string. Therefore, the flight
time fluctuations of a probe light can be manipulated by changing the electric
permittivity and magnetic permeability of the analogue medium. We argue that it
seems possible to fabricate a metamaterial that mimics a cosmic string with a
large $\nu$ in laboratory so that a currently observable flight time variance
might be achieved.
