LAUSR

Controllable random lasers based on two-dimensional (2D) random gain systems with nematic liquid crystals are investigated by using the finite-difference time-domain (FDTD) methods. The dependence of random lasers on the scattering strength of nematic liquid crystals is studied. The results show that the random laser characteristics including the pump threshold, the emission intensity and the number of laser modes can be controlled by varying the pump rates, the filling fraction of nematic liquid crystals, and the included angle between the polarization direction of pump beam and the director of nematic liquid crystals. To achieve the optimal random lasers, the polarization direction of pump beam should be parallel to the director of nematic liquid crystals.