High-precision FoM measurement setup for Ti:sapphire crystals.

Area of Science:

• Laser physics
• Materials science
• Optical engineering

Background:

• Ti:sapphire (Ti:Sa) crystals are crucial for tunable lasers, but their quality assessment via figure of merit (FoM) lacks precision.
• Current FoM measurements using commercial spectrometers yield unsatisfactory precision (±60%), hindering detailed material characterization.

Purpose of the Study:

• To develop and validate a high-precision measurement setup for Ti:Sa crystal FoM.
• To significantly improve the precision of FoM determination compared to existing methods.
• To investigate the impact of crystal inhomogeneities on FoM values.

Main Methods:

• A novel single-pass transmission measurement setup utilizing Nd:YAG and Er:YAG lasers at 532, 780, and 1560 nm.
• Synchronous detection with a double integrating sphere to achieve low transmission uncertainty (0.01-0.03%).

Main Results:

• Achieved a 3σ precision of ±7.5% for FoM measurements, an eightfold improvement over commercial methods.
• Successfully traced spatial inhomogeneities in an unannealed Ti:Sa crystal from a commercial manufacturer.
• Demonstrated that crystal inhomogeneities and angular misalignment significantly affect FoM values.

Conclusions:

• The developed setup provides unprecedented precision for Ti:Sa crystal FoM assessment.
• High-precision FoM measurements are essential for identifying and understanding crystal defects and their impact on laser performance.
• This method enables more rigorous quality control for Ti:Sa crystals used in demanding laser applications.