ZnGeP2 optical parametric oscillator with 3.8-12.4-mum tunability

Area of Science:

• Nonlinear Optics
• Laser Physics
• Spectroscopy

Background:

• Optical parametric oscillators (OPOs) are crucial for generating tunable laser light.
• Zinc germanium phosphide (ZnGeP>(2) or ZGP) is a nonlinear crystal with potential for mid-infrared applications.

Purpose of the Study:

• To demonstrate a wide mid-infrared tunable ZGP-based OPO.
• To investigate the performance characteristics of the ZGP OPO, including tunability, threshold, and efficiency.
• To showcase the application of the narrow-linewidth ZGP OPO for sensitive gas detection.

Main Methods:

• A singly resonant, angle-tuned ZGP OPO was developed.
• The OPO was pumped using 100-ns erbium laser pulses at 2.93 µm.
• Intracavity etalons were employed to narrow the OPO linewidth.

Main Results:

• Continuous tuning from 3.8 to 12.4 µm (type I) and 4 to 10 µm (type II) was achieved.
• Low OPO pump thresholds (<1 mJ) and high quantum conversion efficiency (up to 35%) were observed.
• Linewidth narrowing to <0.5 cm⁻¹ was demonstrated using an intracavity etalon.
• Sensitive detection of N(2)O gas was successfully performed.

Conclusions:

• The ZGP OPO provides a versatile and efficient source for mid-infrared applications.
• The narrow-linewidth capability enables high-sensitivity spectroscopic measurements.
• This technology holds promise for various applications, including environmental monitoring and gas sensing.