Efficient Generation of Mid-infrared Single Fundamental Solitons in ZBLAN Fibers Using a 2 μm Few-Cycle All-Fiber Pumping Mechanism

Achieving high-order soliton suppression and fundamental soliton efficiency enhancement remain critical challenges in all-fiber mid-infrared (MIR) Raman soliton-based femtosecond pulse generation. To address these challenges, we developed a fiber-based nonlinear pulse compression (NPC) system that successfully reduced a 1970 nm, 49.8 MHz, 1.1 W, 254 fs pulse to approximately 36 fs with an impressive efficiency of 83.4%. Employing this compressed pulse to pump ZBLAN fibers enabled single fundamental soliton emission at 3.053 μm with a record-breaking conversion efficiency (CE) of 51.2%; by optimizing fiber lengths, CE reached nearly 90% of the Stokes efficiency limit at 2.90 μm. The system demonstrated exceptional overall efficiency (>63.4%), coupled with excellent long-term power stability (root mean square, RMS≈0.23%) over 2 hours and near-diffraction-limited beam quality (M² ≈ 1.1). These experimental results align well with theoretical predictions, confirming the reliability and practicality of this approach for generating ultrafast MIR pulses. These advancements hold significant promise for applications in sensing, material processing, and spectroscopy.