  In this paper we present a new three dimensional (3D) full electromagnetic
relativistic hybrid plasma code H-VLPL (hybrid virtual laser plasma
laboratory). The full kinetic particle-in-cell (PIC) method is used to simulate
low density hot plasmas while the hydrodynamic model applies to the high
density cold background plasma. To simulate the linear electromagnetic response
of the high density plasma, we use a newly developed form of an exponential
integrator method. It allows us to simulate plasmas of arbitrary densities
using large time steps. The model reproduces the plasma dispersion and gives
correct spatial scales like the plasma skin depth even for large grid cell
sizes. We test the hybrid model validity by applying it to some physical
examples.
