Tantalo-gallate glass as robust nonlinear medium for mid-infrared photonics

The mid-infrared (MIR) photonics market is rapidly expanding, driven by advancements in fiber-based MIR devices, particularly fiber lasers. However, the lack of robust MIR optical fibers remains a critical barrier to further technological progress. In this work, we present the fabrication of gallate glasses containing tantalum oxide, as it stands, the most robust mid-infrared glasses capable of being easily shaped into large bulk components, fibers or tapers. By introducing up to 20 mol% of tantalum oxide in a gallate glass, we achieve a two-order-of-magnitude improvement in water corrosion resistance, while the nonlinear refractive index increases tenfold compared to silica. Optimal thermal stability is attained at 10 mol% of tantalum oxide, enabling the fabrication of tens-of-meter-long optical fibers. Crucially, the addition of tantalum oxide enhances the gallate glass properties without compromising thermomechanical performance. The potential of these tantalo-gallate glasses is further demonstrated through supercontinuum generation in a laser-inscribed waveguide and a tapered fiber, spanning from the visible to 4.5 μm. This work establishes our developed tantalo-gallate glasses as a compelling alternative for photonic applications seeking robust mid-infrared materials, with the potential to overcome the critical barriers currently limiting the advancement of fiber-based MIR technologies. The expanding mid-infrared (MIR) photonics market faces a significant challenge due to the lack of durable MIR optical fibers. Here, the authors fabricate gallate glasses with tantalum oxide, achieving enhanced water corrosion resistance and nonlinear refractive index, paving the way for robust long-length optical fibers, and advancing fiber-based MIR technologies.