Parasitic-light-suppressed quasi-phase-matched optical parametric oscillation device

Area of Science:

• Nonlinear optics
• Laser physics
• Materials science

Background:

• Nonlinear absorption, including green-induced infrared absorption (GRIIRA), poses a significant risk of catastrophic damage in high peak-power wavelength conversion processes.
• Parasitic nonlinear processes, such as second-harmonic generation (SHG), can compete with desired processes like optical parametric oscillation (OPO), leading to inefficiencies and potential damage.

Purpose of the Study:

• To propose and demonstrate a novel concept for suppressing parasitic green second-harmonic generation (SHG) in optical parametric oscillation (OPO).
• To mitigate the risk of catastrophic damage associated with nonlinear absorption during high peak-power wavelength conversion.

Main Methods:

• Utilizing specially engineered quasi-phase-matched (QPM) structures designed to selectively suppress SHG.
• Implementing a relative π-phase shift within the QPM structure specifically for the SHG process, while preserving the OPO process.
• Comparing the performance of the parasitic-light-suppressed (PLS) QPM device with a conventional periodic QPM device.

Main Results:

• The engineered QPM device successfully suppressed parasitic green SHG.
• The parasitic-light-suppressed (PLS) QPM device exhibited a smaller normalized conversion efficiency in the green spectrum compared to a periodic device.
• The PLS QPM device maintained the singly resonant optical parametric oscillation (OPO) performance.

Conclusions:

• Engineered QPM structures offer an effective method for suppressing parasitic SHG in OPO systems.
• Selective phase manipulation within QPM structures is a viable strategy to enhance device performance and prevent damage.
• This approach contributes to the development of more robust and efficient high peak-power nonlinear optical devices.