13.1 W, high-beam-quality, narrow-linewidth continuous-wave fiber-based source at 970 nm

Area of Science:

• Laser Physics
• Nonlinear Optics
• Materials Science

Background:

• High-power, continuous-wave (cw) laser sources are crucial for various scientific and industrial applications.
• Efficient generation of visible and near-infrared radiation often requires nonlinear optical processes.

Purpose of the Study:

• To report an efficient, compact, and practical fiber-laser-based source of high-power, cw, linearly-polarized radiation at 970 nm.
• To demonstrate the effectiveness of direct single-pass second-harmonic-generation (SP-SHG) for this application.

Main Methods:

• Utilized a cw thulium fiber laser operating at 1940 nm as the fundamental source.
• Employed direct single-pass second-harmonic-generation (SP-SHG) in a 40-mm-long periodically-poled lithium niobate (PPLN) crystal.
• Performed theoretical calculations to characterize the SP-SHG process.

Main Results:

• Generated 13.1 W of output power at 970 nm from 40 W of fundamental power.
• Achieved a high conversion efficiency of up to 32.7%.
• The generated second-harmonic output exhibited power stability better than 1.4% over 1 hour, a linewidth < 0.3 nm, and a TEM(00) spatial beam profile (M²<1.6).

Conclusions:

• The developed fiber-laser system offers an efficient and practical solution for generating high-power 970 nm radiation.
• Direct SP-SHG in PPLN is a viable method for achieving high conversion efficiencies in this wavelength range.
• The source's stability and beam quality make it suitable for demanding applications.