Greater than 100% photon-conversion efficiency from an optical parametric oscillator with intracavity...

Area of Science:

• Nonlinear optics
• Laser physics
• Materials science

Background:

• Optical parametric oscillators (OPOs) are crucial for generating tunable laser light.
• Intracavity frequency mixing techniques can enhance OPO performance.
• Periodically poled lithium niobate (PPLN) is a versatile nonlinear material for frequency conversion.

Purpose of the Study:

• To investigate the effect of intracavity difference-frequency mixing (DFM) on OPO performance.
• To optimize idler power and photon conversion efficiency.
• To suppress backconversion and improve pump depletion.

Main Methods:

• Synchronous pumping of a singly resonant OPO using 100-ps Nd:YAG laser pulses.
• Employing intracavity DFM between the OPO signal and idler waves.
• Utilizing periodically poled lithium niobate (PPLN) for both OPO and DFM interactions.
• Operating at signal, idler, and difference wavelengths near 1.5, 3.5, and 2.8 micrometers.

Main Results:

• Achieved an 80% enhancement in idler power-conversion efficiency.
• Demonstrated an idler photon-conversion efficiency of 110% with phase-matched DFM.
• Observed suppression of pump backconversion when DFM was phase matched.
• Increased pump depletion from 65% to 79% at full pump power.

Conclusions:

• Intracavity DFM is an effective method for significantly improving OPO idler output.
• Phase matching the DFM interaction is critical for maximizing efficiency and controlling nonlinear processes.
• The PPLN-based OPO with intracavity DFM shows high potential for efficient light generation in the mid-infrared spectrum.