High-efficiency mid-infrared optical parametric oscillator based on PPMgO:CLN

Area of Science:

• Laser Physics
• Nonlinear Optics
• Materials Science

Background:

• Mid-infrared (mid-IR) lasers are crucial for spectroscopy, sensing, and medical applications.
• Developing high-efficiency and compact mid-IR laser sources remains a significant challenge.
• Quasi-phase-matched (QPM) optical parametric oscillators (OPOs) offer a versatile platform for generating tunable mid-IR radiation.

Purpose of the Study:

• To experimentally demonstrate a high-efficiency, single-resonated OPO for mid-IR laser generation.
• To investigate the performance of a periodically poled magnesium oxide-doped congruent lithium niobate (PPMgO:CLN) crystal in an OPO configuration.
• To characterize the output power, efficiency, and beam quality of the generated mid-IR laser.

Main Methods:

• A single-resonated OPO utilizing a PPMgO:CLN crystal was designed and constructed.
• The OPO was pumped by a 1064 nm, acousto-optically Q-switched diode-side-pumped Nd:YAG laser with an elliptical beam.
• The crystal's orientation and temperature were optimized for efficient nonlinear frequency conversion (e-ee interaction).

Main Results:

• Average output powers of 16.7 W at 3.84 µm and 46 W at 1.47 µm were achieved.
• A slope efficiency of 19.1% was obtained for the 3.84 µm laser output with respect to the pump power.
• The M(2) factors of the 3.84 µm laser were measured as 2.03 (parallel) and 5.89 (perpendicular) to the beam propagation.

Conclusions:

• The study successfully demonstrated a high-efficiency mid-IR laser based on a QPM OPO in PPMgO:CLN.
• The achieved output powers and efficiency highlight the potential of this system for practical mid-IR applications.
• Further optimization of beam shaping and crystal properties could lead to improved beam quality and higher output powers.