Numerical Demonstration of the Enhanced 3.7 μm Dispersive Wave Generation in an Er-Doped Fluorotellurite Fiber

We investigate theoretically the enhanced 3.7 μm mid-infrared (MIR) dispersive waves (DWs) generation in Er-doped fluorotellurite fibers with two zero-dispersion wavelengths (ZDWs). This model includes Raman soliton generation, soliton self-frequency shift (SSFS), soliton gain, and DW generation. Making full use of the Er³⁺ gain band, the soliton located in 2.8 μm is amplified and then radiates an enhanced 3.7 μm MIR DW. With a 20 dB/m gain, the output DW energy from the Er-doped fluorotellurite fiber exhibits a 14-fold enhancement compared to the no-gain case, while the soliton-to-DW conversion efficiency increases from 41% to 79%. We design different dispersion curves by changing the core diameter and obtaining different wavelength DWs ranging from 3.0 to 3.9 μm. Further, we investigated general methods to optimize the pulse energy, pulse width of Raman solitons and DWs, and conversion efficiency. Increasing the pump power or fiber length can both enhance the DW energy and improve the conversion efficiency from solitons to DWs. The narrowest Raman soliton pulse width can be achieved by optimizing the fiber length. Our results offer significant insights for achieving high-energy, high-efficiency 3.7 μm MIR picosecond laser generation.