Fiber-loop laser with a cooled erbium-doped section

An optical comb featuring an unusual structure has been recently observed in a fiber-loop laser running at cryogenic temperatures. In the present work, the effect of optical polarization on the operation of the laser is explored. Multi-mode lasing with a relatively high degree of inter-mode coherency is experimentally demonstrated. The setup can be used for applications to spectroscopy, communications, and quantum data storage.