Distributed feedback laser action by polarization modulation

Abstract.

Laser action was generated in dye-doped sol–gel glass waveguides and in liquid solutions by crossing two beams from a frequency-doubled neodymium:YAG laser. The angle between the polarization directions of the two beams was varied continuously from 90. The case of 0° corresponded to pure intensity modulation. As the angle increased, the degree of intensity modulation decreased, resulting in the decline and finally the demise of the laser output. At 90°, corresponding to pure polarization modulation, distributed feedback laser action with narrow line-width output was again observed when the pump energy was increased three-fold. The laser output also showed different polarization characteristics when the feedback mechanism was changed from intensity modulation to polarization modulation.