• • Cation hybridization with Mg2+ and Ba2+ in germanate glass yields a stable multi-band NIR emission spanning 920, 1142, 1265, and 1516 nm with a record bandwidth of 526 nm, enabling optical amplification across O+E+S+C bands (1260–1675 nm) and potentially doubling the usable bandwidth of current Er-doped fiber amplifiers (1530–1610 nm).
• • The strategy achieves a positive on-off gain in multiple communication bands (O, E, S, C) in a fabricated Bi-doped hybrid germanate glass fiber, demonstrating net signal amplification without the need for complex multi-stage or hybrid amplifier architectures.
• • By tailoring the local glass network with Ba2+ and repairing it with Mg2+, the variability of Bi active centers (BACs) is suppressed, leading to stable emission at 1142 nm as a single main peak or as part of a multi-band profile, which is critical for reproducible fiber amplifier manufacturing.
• • The ultra-broadband response (526 nm) exceeds the bandwidth of conventional rare-earth-doped glasses by a factor of ~3.5 (typical Er bandwidth ~80 nm), directly addressing the capacity crunch in optical communication systems by covering the entire low-loss transmission window (1260–1675 nm).