Efficient conversion from 1 to 2 microm by a KTP-based ring optical parametric oscillator

Area of Science:

• Nonlinear Optics
• Laser Physics
• Materials Science

Background:

• Nd:YAG lasers are common sources for optical parametric oscillators (OPOs).
• Generating specific wavelengths requires efficient nonlinear optical processes.
• Walk-off compensation is crucial for high-efficiency OPOs.

Purpose of the Study:

• To demonstrate efficient wavelength conversion of 1.064-micrometer Nd:YAG laser pulses.
• To achieve high-efficiency generation in the 2-2.2-micrometer and 3-5-micrometer spectral regions.
• To investigate the performance of KTP and ZnGeP2 based OPOs.

Main Methods:

• Utilized a KTP-based type 2 phase-matched optical parametric oscillator (OPO) in a ring resonator.
• Employed two pairs of walk-off compensating crystals for enhanced performance.
• Cascaded a ZnGeP2-based OPO pumped by the signal from the KTP OPO.

Main Results:

• Achieved 46% conversion efficiency for Nd:YAG laser pulses to the 2-2.2-micrometer region.
• Obtained 2.5 mJ signal at 2.06-micrometer and 2.1 mJ idler at 2.2-micrometer with 10 mJ pump energy.
• Demonstrated a beam quality of M(2) approximately 1.4.
• Achieved 14% conversion efficiency from 1.064-micrometer to the 3-5-micrometer range using the cascaded ZnGeP2 OPO.

Conclusions:

• KTP-based OPOs with walk-off compensation are highly efficient for mid-infrared generation.
• Cascaded OPO systems offer a viable route for generating longer infrared wavelengths.
• The demonstrated efficiencies pave the way for advanced infrared laser applications.