Design and fabrication of all-solid anti-resonant silicate fibers for Yb ASE suppression in Er/Yb fiber amplifier

In this paper, we report the design, fabrication and characterization of a passive silicate-glass-based all-solid anti-resonant fiber (AS-ARF) for ~1 μm transmission suppression. Simulation results demonstrate that the AS-ARF achieves a first high higher order mode (HOM) suppression ratio of over 25 dB in a 26-63 μm core diameter at 1550 nm. Using the drilling and rod-in-tube technique, an AS-ARF with a core diameter of 43 μm and high-refractive-index capillaries (HRICs) thickness of 1.44 μm was fabricated. Furthermore, a wide transmission window around 1.5 μm, and a high-loss resonant band ranging from 1 μm to 1.1 μm were measured, which agrees well with the simulation. By fusion spliced a 12 cm-long AS-ARF in the EYDF amplifier, amplified spontaneous emission (ASE) and parasitic oscillations of Yb3+ ions are effectively suppressed, and the loss at 1030 nm is 12.3 dB higher than that at 1550 nm. To the best of our knowledge, this is the first time that an AS-ARF can achieve ~1 μm transmission suppression and single-mode propagation in the 1.5 μm band. The novel fiber structure option holds potential for further application in rare-earth-doped fiber amplifiers and lasers, including those doped with Nd, Yb, Er, Tm, and other rare-earth elements.