Crystalline selenium core optical fibers with low optical loss

Amorphous selenium (a-Se) core fibers with glass cladding have immediately been fabricated using the molten core method. The high aspect ratio of the a-Se core fibers and the presence of the glass cladding surrounding the Se core make it convenient to convert the a-Se core into a polycrystalline structure. It is found that the two-step thermal annealing process allows for the increase of crystal grain size and decrease of the structure defects in the Se core. Therefore, a low propagation loss of 1.5 dB/cm at 1310 nm has been realized for the polycrystalline selenium (c-Se) core optical fibers obtained by the wo-step annealing a-Se core fibers, first at a 80 degrees C low temperature annealing followed by a 207 degrees C high temperature annealing, which is much lower than that reported for c-Se core optical fibers (2.6 dB/cm). (C) 2017 Optical Society of America