  While two highly intensive laser beams collide, they create a region where
the refractive index varies so quickly that photons are created. The variance
of the refractive index is analog to the universe scale factor variance.
Therefore, this laser system can be an analog to the expansion of the universe.
We find that several hundreds of photons can be created under feasible
conditions. This system can demonstrate the particle creation during inflation
or other similar periods.
