Absorptive bistability in a three-level system interacting with two fields

We have studied the case of purely absorptive bistability in a three-level system interacting with two coherent fields. The results show that in the limit where the neglect of propagation effects is justified, a tunable optical device (TOD) results. It is shown that varying the secondary field amplitude can alter the hysteresis curve of the two-level system dramatically. Under certain conditions, the secondary applied field can eliminate hysteresis and produce a tunable differential gain region. This type of adaptive behavior offers attractive possibilities for optically based analog-digital systems.