Multimilliwatt, tunable, continuous-wave, mid-infrared generation across 4.6-4.7  μm based on orientation-patterned...

Area of Science:

• Nonlinear optics
• Solid-state physics
• Laser technology

Background:

• Continuous-wave (cw) mid-infrared (mid-IR) radiation is crucial for spectroscopy and sensing.
• Existing methods for mid-IR generation often face limitations in tunability, power, or material properties.

Purpose of the Study:

• To demonstrate the capability of orientation-patterned gallium phosphide (OP-GaP) as a nonlinear material for mid-IR generation.
• To characterize the performance of a mid-IR source based on OP-GaP.

Main Methods:

• Difference-frequency mixing (DFM) of a Tm-fiber laser and a custom optical parametric oscillator (OPO).
• Utilizing a 40-mm-long OP-GaP crystal for nonlinear frequency conversion.
• Investigating temperature acceptance bandwidth, power stability, and beam quality.

Main Results:

• Tunable cw mid-IR radiation generated across 4608-4694 nm.
• Maximum output power of 43 mW achieved, with >30 mW across >95% of the tuning range.
• High beam quality and passive power stability of 2.5% rms at 4608 nm.

Conclusions:

• OP-GaP is a promising nonlinear material for efficient cw mid-IR generation.
• The developed mid-IR source demonstrates excellent performance characteristics.
• Further investigation into high pump powers and polarization effects in OP-GaP is warranted.