Two-layer single-crystal fiber waveguides

Preliminary results are reported on the fabrication and investigation of two-layer fiber waveguides with a core and cladding made of single crystals of thallium (TlBr–TlCl) and cesium (CsBr–CsCl) halides. A considerable reduction in the optical losses was achieved in waveguides with a cladding and a coating, compared with uncoated fibers.