Rapidly tunable optical parametric oscillator based on aperiodic quasi-phase matching.

Area of Science:

• Photonics and Laser Technology
• Nonlinear Optics
• Spectroscopy

Background:

• Optical parametric oscillators (OPOs) are crucial for tunable coherent light generation.
• Traditional OPOs often require slow tuning mechanisms involving crystal adjustments (temperature, angle, position).
• Aperiodic quasi-phase matching (QPM) offers a path to broader spectral bandwidths in nonlinear optical devices.

Purpose of the Study:

• To demonstrate a new OPO architecture with high tuning speed capability.
• To leverage aperiodic QPM for broad gain spectra without mechanical adjustments.
• To integrate a fast intracavity spectral filter for rapid wavelength tuning.

Main Methods:

• Development of a picosecond synchronously pumped OPO.
• Utilized an aperiodically poled MgO-doped LiNbO3 crystal.
• Incorporated a rapidly tunable diffraction grating-based spectral filter.
• Tested and compared different OPO configurations, analyzing cavity length detuning.

Main Results:

• Achieved tuning over 160 nm around 3.86 μm at a fixed temperature.
• Demonstrated fast tuning of 30 nm within 40 μs.
• Successfully applied the OPO for N2O detection via absorption spectroscopy.
• Validated the OPO's broad parametric gain spectrum without crystal manipulation.

Conclusions:

• The demonstrated aperiodic QPM OPO architecture provides high tuning speed and broad spectral coverage.
• This approach simplifies tuning and enhances the applicability of OPOs.
• The technology is adaptable for various spectral ranges and temporal regimes, including visible light and continuous-wave or nanosecond operation.