Mid-IR luminescence of Cr2+ : II — VI crystals in chalcogenide glass fibres

Optical fibres have been fabricated for the first time from As₂S₃ glass containing chromium-doped ZnS and ZnSe crystals, and their optical loss and luminescence spectra have been measured in the mid-IR. In the spectral range 2 — 3 μm, the optical loss in the fibres is 2 — 4 dB m^-1. The fibres have a broad luminescence band in the range 1.8 — 3 μm, with a maximum near 1.9 μm, which is due to Cr^{2+ 5}E — ⁵T₂ intracentre transitions in the II - VI host.