Green-pumped continuous-wave parametric oscillator based on fanout-grating MgO:PPLN.

Area of Science:

• Nonlinear Optics
• Laser Physics

Background:

• Continuous-wave (cw) optical parametric oscillators (OPOs) are crucial for generating tunable laser light.
• MgO:PPLN crystals offer significant nonlinear optical properties for OPO development.
• Green-pumped OPOs are desirable for compact and efficient laser systems.

Purpose of the Study:

• To demonstrate the first green-pumped cw OPO utilizing MgO:PPLN in a fanout grating configuration.
• To characterize the tuning range, output power, beam quality, and stability of the developed OPO.
• To investigate the factors limiting power scaling in this OPO system.

Main Methods:

• A single-frequency cw laser at 532 nm was used as the pump source.
• A MgO:PPLN crystal with a fanout grating design was employed.
• Mechanical translation and output coupling for the signal wave were utilized for tuning and power extraction.

Main Results:

• Tunable radiation was achieved across 813-1032 nm (signal) and 1098-1539 nm (idler) at a fixed temperature of 55°C.
• Up to 714 mW of output power was generated with 30% extraction efficiency.
• Excellent Gaussian beam quality (M²<1.1) and high output stability (2.8% and 1.8% rms for signal and idler over 1 hour) were observed.
• The output signal exhibited a single-mode profile with a linewidth of ~3 MHz and frequency stability of ~84 MHz over 72 s.

Conclusions:

• The developed green-pumped cw OPO based on MgO:PPLN demonstrates efficient and stable tunable radiation generation.
• Thermal effects significantly contribute to the OPO's stability and beam quality.
• Linear and green-induced infrared absorption currently limit the OPO's power scaling capabilities.