A mid‐infrared (MIR) supercontinuum (SC) has been demonstrated in a low‐loss telluride glass fiber. The double‐cladding fiber, fabricated using a novel extrusion method, exhibits excellent transmission at 8–14 μm: < 10 dB/m in the range of 8–13.5 μm and 6 dB/m at 11 μm. Launched intense ultrashort pulsed with a central wavelength of 7 μm, the step‐index fiber generates a MIR SC spanning from ∼2.0 μm to 16 μm, for a 40‐dB spectral flatness. This is a fresh experimental demonstration to reveal that telluride glass fiber can emit across the all MIR molecular fingerprint region, which is of key importance for applications such as diagnostics, gas sensing, and greenhouse CO₂ detection. image

Chalcogenide glasses have the advantages of a wide transparency window (over 20 μm) and high optical nonlinearity (up to a thousand times greater than that of silica glasses), making them good candidates for mid-infrared supercontinuum generation. In this review, we describe both the history and recent developments in mid-infrared supercontinuum generation from chalcogenide fibers according to three kinds of fiber structures: step-index, microstructured and tapered fibers. We also review the coherence properties of mid-infrared supercontinuum generation and all-fiber supercontinuum sources based on chalcogenide fibers.

We have experimentally demonstrated midinfrared (MIR) supercontinuum (SC) generation in a low-loss Te-based chalcogenide (ChG) step-index fiber. The fiber, fabricated by an isolated extrusion method, has an optical loss of 2–3 dB/m at 6.2–10.3 μm and 3.2 dB/m at 10.6 μm, the lowest value reported for any Te-based ChG step-index fiber. A MIR SC spectrum ($\sim 1.5$ to 14 μm) is generated from the 23-cm fiber pumped by a 4.5 μm laser ($\sim 150\mathrm{fs}$, 1 kHz). To the best of our knowledge, this is the first SC experimental demonstration in Te-based ChG fiber and the broadest MIR SC generation pumped in the normal dispersion regime in the optical fibers.

We have prepared a well-structured tellurium chalcogenide (ChG) fiber with a specialized double cladding structure by an improved extrusion method, and experimentally demonstrated an ultra-flat mid-infrared (MIR) supercontinuum (SC) generation in such a fiber. The step-index fiber had an optical loss of <1 dB/m in a range from 7.4 to 9.7 μm with a minimum loss of 0.69 dB/m at 7.87 μm. Simulation showed that an all-normal dispersion profile can be realized in this double cladding tellurium fiber. An ultra-flat MIR SC spectrum (~3.2-12.1μm at −10 dB, ~2-14 μm at −30 dB) was generated from a 22-cm long fiber pumped with a femtosecond laser at 5 μm (~150 fs, 1 kHz). Then the degree of coherence was calculated out based on a simulation, showing that a high coherent MIR SC (from 2.9 to 13.1 μm) can be generated in this double-cladding tellurium fiber.