A highly stable monolithic enhancement cavity for second harmonic generation in the ultraviolet

Area of Science:

• Nonlinear Optics
• Laser Physics
• UV Generation

Background:

• Second harmonic generation (SHG) is crucial for producing UV light.
• Power enhancement cavities increase the efficiency of nonlinear processes like SHG.
• Previous cavities faced limitations in stability and robustness for practical applications.

Purpose of the Study:

• To present a highly stable bow-tie power enhancement cavity for critical SHG into the UV.
• To demonstrate the cavity's suitability for a wide range of UV wavelengths and nonlinear frequency conversion.
• To assess the system's operational stability and robustness under various conditions.

Main Methods:

• Utilized a Brewster-cut beta-barium borate (BBO) nonlinear crystal within a bow-tie cavity.
• Implemented a fast digital PI controller (STEMlab 125-14) for precise length stabilization.
• Tested system robustness through exposure to sustained and random accelerations.

Main Results:

• Achieved 130 hours of uninterrupted SHG operation at 313 nm without power decay.
• Demonstrated less than 10% output power variation under 1g acceleration.
• Confirmed stability under 3 g_rms acceleration for 30 minutes.

Conclusions:

• The developed bow-tie cavity offers high stability and robustness for UV generation via SHG.
• The design is adaptable for various UV wavelengths and nonlinear conversion processes.
• The system's resilience makes it suitable for transportable laser setups.