OPTICAL BISTABILITY AND LASING WITHOUT INVERSION IN A SYSTEM OF DRIVEN 2-LEVEL ATOMS WITH INCOHERENT INJECTION

We have studied a laser system in which initially incoherent atoms are injected into a cavity and directly driven by a coherent pump field. Here we show that such a system can display optical bistability in the absence of population inversion. Two disconnected branches of the sol utions are obtained for lasing action. They correspond to the inversio n branch and inversionless branch, respectively. Also, a mechanism is proposed here to produce higher-power lasing by the inversionless lase r.