High-Power, Continuous-Wave, Fiber-Pumped Difference-Frequency-Generation at 2.26 μm

We report a high-power source of continuous-wave (cw) mid-infrared (mid-IR) radiation at 2.26 mu m based on difference-frequency-generation (DFG) of a cw Yb-fiber laser at 1.064 mu m and a cw Tm-fiber laser at 2.010 mu m in MgO:PPLN. Using a 50-mm- long crystal with a single grating period of 32.16 mu m and a simple single-pass setup, we generate up to 3.84 W of cw output power at 2.26 mu m at a power conversion efficiency of similar to 0.47%/W. The DFG output beam is characterized by a Gaussian TEM00 spatial profile with M-2 < 1.2, and exhibits excellent passive power stability of 0.6% rms and spectral stability better than 0.01% over 1 hour. We find close agreement between the measured conversion efficiencies and theoretical predictions, confirming optimum performance of the DFG source. Our approach represents a viable and practical alternative to the existing methods for generating this useful wavelength. To the best of our knowledge, the generated output represents the highest cw power obtained from any single-pass nonlinear frequency conversion source in the mid-IR.

Automated summary

The article reports a high-power source of continuous-wave mid-IR radiation based on difference-frequency-generation of Yb-fiber laser and Tm-fiber laser, achieving a power conversion efficiency of about 0.47%/W. The generated output represents the highest cw power obtained from any single-pass nonlinear frequency conversion source in the mid-IR, with excellent passive power stability and spectral stability.