Compact, 1.5 mJ, 450 MHz, CdSiP2 picosecond optical parametric oscillator near 6.3 μm

Area of Science:

• Nonlinear optics
• Laser physics
• Materials science

Background:

• Mid-infrared lasers are crucial for various applications, including surgery.
• Developing efficient and high-energy laser sources in this spectral range remains a challenge.

Purpose of the Study:

• To report a compact, high-energy, high-repetition-rate mid-infrared picosecond optical parametric oscillator (OPO).
• To evaluate the performance of a novel nonlinear material, Cadmium Silicon Phosphide (CdSiP2 - CSP), in an OPO system.
• To assess the suitability of the developed OPO for surgical applications.

Main Methods:

• Synchronous pumping of a compact OPO cavity using a master oscillator power amplifier system at 1064.1 nm.
• Utilizing a high-quality CdSiP2 nonlinear crystal.
• Tuning the OPO output wavelength and measuring energy, efficiency, pulse duration, and beam quality.

Main Results:

• Achieved tunable output from 6091-6577 nm with a tuning range of 486 nm.
• Obtained a maximum idler macropulse energy of 1.5 mJ at 6275 nm with a photon conversion efficiency of 29.5%.
• Demonstrated high beam quality (Gaussian profile) for both signal and idler beams, with signal pulse durations of 10.6 ps.
• Estimated the two-photon absorption coefficient of CSP as β=2.4 cm/GW and energy bandgap as E(g)=2.08 eV.

Conclusions:

• The CdSiP2-based OPO is a compact and efficient source of high-energy mid-infrared picosecond pulses.
• The demonstrated performance and tuning range make it suitable for surgical applications.
• The material properties of CSP indicate its potential for high-power nonlinear optical applications.