Members of of IRG-I have recently introduced a new concept in fiber lasers. Until now, emission from fiber lasers originated solely from the fiber ends in the axial direction with a spot size dictated by the core radius. In contrast, these novel lasers, termed surface-emitting fiber lasers (SEFLs), emit radiation radially and are capable of dynamic tuning of both the gain-medium position along the fiber axis and the direction of emission.These interesting results suggest that the direction of the laser beam can be controlled remotely just by rotating the pump polarization. Another key aspect of the SEFL is that the gain medium need not be fixed in place with respect to the fiber. By introducing a mobile gain medium into the fiber core, it is possible to engineer a SEFL with a highly-collimated dynamically tunable lasing position as shown in the Figure. Thus any point along the fiber may be utilized for lasing, as needed, in real time. Motion control is achieved from one end of the fiber by a series of electronically controlled microdispensing solenoid valves connected to a positive pressure source and a vacuum generator to allow displacement of the dye doped fluid-plug in both axis directions. SEFLs could provide enhanced capabilities for diverse technologies, including medical imaging, explosive vapor and chemical detection, photodynamic therapy, and fabric displays.
