3.5  W long-wave infrared ZnGeP₂ optical parametric oscillator at 9.8  µm.

Area of Science:

• Optics and Photonics
• Laser Physics
• Materials Science

Background:

• Optical parametric oscillators (OPOs) are crucial for generating tunable laser light.
• High-power sources in the long-wave infrared (LWIR) spectrum are essential for various applications.
• ZnGeP2 (ZGP) is a promising nonlinear crystal for infrared generation.

Purpose of the Study:

• To demonstrate a high-power, 9.8 µm LWIR optical parametric oscillator.
• To investigate the performance of a ZnGeP2 crystal in a high-power OPO setup.
• To characterize the output parameters of the developed LWIR OPO.

Main Methods:

• Utilized a type-I phase-matching ZnGeP2 crystal.
• Employed a Q-switched 2091 nm Ho:YAG laser operating at a 10 kHz pulse repetition frequency as the pump source.
• Characterized output power, slope efficiency, conversion efficiency, pulse width, linewidth, and beam quality (M²).

Main Results:

• Achieved a maximum average output power of 3.51 W at 9.8 µm with 90 W of incident pump power.
• Obtained a slope efficiency of 4.81% and a conversion efficiency of 3.9% at maximum pump power.
• Measured a pulse width of 19.6 ns, a linewidth of 142 nm, and a beam quality factor M² of approximately 2.2.

Conclusions:

• Successfully demonstrated a high-power LWIR OPO at 9.8 µm using a ZnGeP2 crystal.
• The developed OPO exhibits efficient power conversion and good beam quality.
• This high-power LWIR source has potential applications in spectroscopy, remote sensing, and directed energy.