Flexible chalcogenide glass large-core multimode fibers for hundred-watt-level mid-infrared 2-5 µm laser transmission

Abstract

The rapidly-developed high-power mid-infrared 2-5 µm laser technology requires a compact, flexible low-loss glass fiber for power delivery or laser generation. With the broadest bandwidth of low-loss transmission window in mid-infrared region amongst all mid-infrared glass fibers, chalcogenide glass fiber is the best candidate covering the whole 2-5 µm range. Multi-hundred-watt high-power delivery for 5.4-µm CO laser was previously demonstrated in a multimode chalcogenide fiber with a 1-mm-diameter large core, at the cost of giving up one of the most desirable fiber advantages, the flexibility. Indeed, chalcogenide glass fibers with decent flexibility have never exhibited hundred-watt-level power transmitting capability in the 2-5 µm range. In this paper, we have experimentally demonstrated 100-watt-level power transmission in multimode As2S3 chalcogenide fibers, using a customized high-power 2-µm thulium doped silica fiber laser source. With effective forced cooling, the multimode As2S3 fiber with 200 µm core diameter can resist incident laser power of 120 W and deliver transmitted power of 63 W. Nano-sized scattering center related laser damage mechanism and the cylindrical heat transfer model have been proposed to explain the high-power damage process of chalcogenide glass fibers. The calculation is in good agreement with the experiments. It is promising to further enhance the transmitted power above 100 W in flexible chalcogenide glass large-core fibers.

Chalcogenide mid‐infrared 3 × 1 fiber combiner for highly efficient 2–5 µm power and wavelength combining

“…The As–S glass material was chosen for fabricating the 3 × 1 fiber combiner in this study due to its excellent MIR transparency, good resistance to crystallization, and relatively high laser damage threshold 13,14 . The structure of the fiber combiner is shown in Figure 1A.…”

“…The As-S glass material was chosen for fabricating the 3 × 1 fiber combiner in this study due to its excellent MIR transparency, good resistance to crystallization, and relatively high laser damage threshold. 13,14 The structure of the fiber combiner is shown in Figure 1A. The preparation process of the combiner includes the preparation of highpurity glass, fiber fabrication, capillary tube preparation, fiber bundle tapering, fiber taper region cutting, output fiber fusion splicing, and fiber combiner armoring.…”

“…The experimental setup was similar to the one shown in our previous work. 14 Figure 3B shows the correlations between the input and output powers. With water cooling at the input side, the fiber can withstand a maximum incident power of ∼81 W, and the transmitted power was ∼43.5 W. Without cooling, the endured maximum incident power was ∼23 W, and the transmitted power was ∼12.3 W. Compared with the fiber in Ref.…”

Progresses of Mid-Infrared Glass Fiber for Laser Power Delivery

“…For pulse durations of 190 ns, the maximum input energy of the pulsed laser was 2.3 mJ, corresponding to a power density of 28.2 MW/cm 2 . In 2022, Qi et al [24] demonstrated a power transmission of 100 W in multi-mode As-S fibers using a high-power 2 µm erbium-doped silicon fiber laser source. With effective cooling, the 200 µm core diameter As-S multimode fibers resisted an incident laser power of 120 W, transmitted 63 W, and handled an incident power density of up to 472 kW/cm 2 .…”

Hundred-meter-scale, kilowatt peak-power, near-diffraction-limited, mid-infrared pulse delivery via the low-loss hollow-core fiber

“…However, fabrication difficulties have significantly hindered the production of long lengths of fiber and hence applications requiring long-distance MIR laser delivery. Current delivery distances have been limited to a few meters' length [10][11][12][13][14]. Moreover, the low damage thresholds, small mode areas, and high nonlinearity of these fibers are also a hindrance to their use in high-power single-mode MIR beam delivery.…”