CONTINUOUSLY TUNABLE RING LASER WITH NONRECIPROCAL FREQUENCY SHIFTERS

Two counteracting frequency shifters and a Fabry-Perot filter represen t a nonreciprocity of the phase or amplitude type. In a fiber ring las er they permit narrow-band unidirectional operation with continuous tu nability and switchable sense of rotation. Electronic stabilization at the switch-over point yields simultaneous operation at two frequencie s.