Phase correction in double-pass quasi-phase-matched second-harmonic generation with a wedged crystal

Area of Science:

• Nonlinear optics
• Laser physics
• Materials science

Background:

• Efficient nonlinear frequency conversion is crucial for many optical applications.
• Dispersive elements like mirrors introduce phase shifts that degrade performance in multiple-pass and intracavity systems.
• Existing compensation methods can be complex or inefficient.

Purpose of the Study:

• To introduce a new method for compensating phase shifts in nonlinear frequency-conversion devices.
• To utilize a wedged quasi-phase-matched crystal for efficient phase compensation.
• To demonstrate enhanced conversion efficiency using this technique.

Main Methods:

• A wedged quasi-phase-matched crystal was designed and fabricated.
• The crystal's periodic structure was exploited to manage phase variations.
• A double-pass second-harmonic generation experiment was conducted using a periodically poled lithium niobate crystal.

Main Results:

• The wedged crystal successfully compensated for phase shifts caused by mirrors.
• A significant enhancement in conversion efficiency was observed in the experiment.
• The results validated the theoretical predictions for phase compensation.

Conclusions:

• Wedged quasi-phase-matched crystals offer an effective solution for phase compensation in nonlinear optics.
• This approach improves the efficiency of multiple-pass and intracavity frequency-conversion devices.
• The technique is applicable to various nonlinear optical processes requiring phase matching.