supported by the National Natural Science Foundation of China (60778003);the Fundamental Research Funds for the Central Universities (2010MS041);the Science Foundation of China Academy of Enginnering Physics NSAF (10876010)
By numerically solving Maxwell's equations and rate equations in a two-dimensional (2D) active random media made of ruby grains with a three-level atomic system, the threshold gain behavior for a THz random laser is i...