Watt-scale near-diffraction-limited mid-infrared laser delivery by a chalcogenide anti-resonant fiber.

We have developed an effective one-step extrusion method to prepare a nodeless chalcogenide hollow-core anti-resonance fiber, characterized by excellent symmetry and less requirements for drawing pressure in achieving the desired wall thickness. The resulting fiber exhibits excellent uniformity, with an ultra-large effective mode area of 21970 µm² and a low overlap factor of η = 0.03%. It can withstand an input power exceeding 10 W at 4.5 µm and maintain a stable output power of 1.2 W at an input power of 5.25 W, all while preserving a high beam quality with an M² value of 1.09. The output single-mode laser remains highly stable when the translation offset of the laser coupling into the fiber is less than 100 µm. The chalcogenide hollow-core fibers with watt-level mid-infrared laser delivery power and near-diffraction-limited beam quality can be used for practical applications in industry, medicine, and defense.