Phosphate glass-clad tellurium semiconductor core optical fibers

• Glass-clad tellurium semiconductor core optical fibers were successfully synthesized.
• The core were found to be highly crystalline and phase-pure.
• The core in fibers have high transparency at infrared wavelength from 4 to 25 μm.
• The tellurium core fibers have great potential utility in Raman fiber amplifiers.

For the first time to the best of our knowledge phosphate glass-clad optical fibers comprising tellurium (Te) semiconductor core have been fabricated using a molten core approach. The cores were found to be highly crystalline and phase-pure as evidenced by X-ray diffraction (XRD) and corroborated by Micro-Raman spectrum. Elemental analysis across the core/clad interface suggests that there is some diffusion of oxygen and phosphorus into the core region and, conversely, diffusion of Te into the cladding region. Unfortunately, the propagation loss of the Te core fibers was too high to measure due to the significant scattering from the grain boundaries, oxygen and phosphor precipitates. However, the larger Raman gain, infrared and terahertz transparency of tellurium over silicon and germanium should make these fibers of significant value for fiber-based mid- to long-wave infrared, terahertz waveguides and Raman-shifted infrared light sources.