Compact and efficient mid-IR OPO source pumped by a passively Q-switched Tm:YAP laser.

Area of Science:

• Optics and Photonics
• Laser Physics
• Materials Science

Background:

• Mid-infrared (mid-IR) light sources are crucial for spectroscopy, sensing, and defense applications.
• Developing compact, efficient, and high-power mid-IR sources remains a significant challenge in laser technology.

Purpose of the Study:

• To demonstrate a novel, compact, and efficient mid-IR source.
• To investigate the performance of zinc germanium phosphide (ZGP) and cadmium silicon phosphide (CSP) optical parametric oscillators (OPOs) pumped by a thulium-doped yttrium-aluminum-perovskite (Tm:YAP) laser.

Main Methods:

• A passively Q-switched Tm:YAP laser, emitting at 1.94 μm, was utilized as the pump source.
• The Tm:YAP laser achieved 4 W average power and 29 kW peak power.
• Doubly resonant linear OPO cavities incorporating CSP and ZGP crystals were employed.

Main Results:

• The OPOs generated mid-IR emission in the 3.5–4.2 μm range.
• Cadmium silicon phosphide (CSP) OPOs produced a maximum output power of 2.5 W with 65% optical conversion efficiency.
• Zinc germanium phosphide (ZGP) OPOs yielded a maximum output power of 2.3 W with 58% optical conversion efficiency.

Conclusions:

• The developed system offers a compact and efficient solution for generating high-power mid-IR radiation.
• Both CSP and ZGP crystals proved effective in OPO cavities for mid-IR generation.
• This work advances the development of practical mid-IR laser sources.