10 W-Level, All-Fiber Supercontinuum Generation From Visible to Mid-Infrared by Broadband Laser Beam Combination in GeO2-Core Fiber

GeO₂-core fibers (GCFs) exhibit higher optical nonlinearity and superior mid-infrared (MIR) transmission properties compared to silica fibers. They also demonstrate greater durability in high-power MIR applications than fluoride fibers, making them ideal for high-brightness, broadband supercontinuum (SC) generation in the visible to MIR region. However, the ZDWs of GCFs are located around 1.6 μm, unable to match well with the common fiber laser wavelengths (e.g., 1.03 μm, 1.55 μm, 2.0 μm), limiting the SC bandwidth. Specifically, pumping GCFs at 1.55 μm with a nanosecond laser can produce SC with good spectral properties in the visible to near-infrared (NIR) region, but its long-wavelength edge (LWE) extends to MIR region is difficult; conversely, although pumping at the 2 μm band, the spectral LWE can extend beyond 3.5 μm, its short-wavelength edge (SWE) is limited to around 1.9 μm. To combine the strengths of these approaches and generate SC covering both visible and MIR regions, we, for the first time, present a broadband SC laser beam combination in a custom-made high-power GCF-based tapered fiber bundle (H-GTFB). The resultant SC covers a spectral range of 0.7–3.5 μm with a maximum average power exceeding 9 W. Moreover, the power fluctuation root mean square (RMS) value was measured to be approximately 0.261% at an average power of 9.12 W over 2.5 hours. These findings significantly contribute to the advancement of high-power, broadband, fiberized SC sources.