Linewidth narrowing of a DFB semiconductor laser at 1.55 mu m by optical injection of an Er : ZBLAN microspherical laser

An Er:ZBLAN microspherical laser has several laser lines around 1.55 mum wi th narrow bandwidths (similar to 50-100 kHz). Such a laser is used as a mas ter laser to optically inject a slave DFB semiconductor laser. We show that the slave can be easily locked by one microsphere mode only, enabling a sp ectral narrowing of the laser line ( from 30 MHz to 67 kHz). We stress the selective process of light amplification and filtering effect by the DFB sl ave.