Enhanced Four‐Wave Mixing From 1.55 to 2.05 μm Enabled by a Black Phosphorus‐Based Highly Nonlinear Microfiber for All‐Optical Wavelength Conversion

ABSTRACT All‐optical wavelength conversion (AOWC) is essential for overcoming wavelength blocking in wavelength‐division multiplexing systems and improving bandwidth utilization. Integrating two‐dimensional materials with optical microfibers presents a promising route to enhance nonlinear performance. Here, we demonstrate an efficient AOWC device based on black phosphorus (BP)‐deposited highly nonlinear microfiber, which operates through the four‐wave mixing (FWM) process. The converter achieves a conversion efficiency of −33.51 dB at 2.05 μm. Systematic characterisation reveals that the efficiency increases by 4.56 dB as the pump power rises from 1.83 to 2.00 mW, whereas it decreases by 16.76 dB when the signal–pump wavelength spacing broadens from 3.5 to 11 nm, consistent with FWM power dependence and phase‐matching constraints. The device also exhibits excellent stability, with power fluctuation within ± 1.08 dB over 140 min. This work provides valuable insights into the nonlinear coupling between 2D materials and microfibers, supporting the development of practical low‐power high‐speed all‐optical signal processing systems.