Prototype optical enhancement cavity for steady-state microbunching

Area of Science:

• Physics
• Laser Technology
• Accelerator Physics

Background:

• Steady-state microbunching (SSMB) offers a high-repetition-rate, coherent radiation source.
• The laser modulator, including an undulator and optical enhancement cavity, is crucial for SSMB.

Purpose of the Study:

• To describe a high-finesse prototype optical enhancement cavity for SSMB.
• To address frequency degeneracy and power coupling challenges in SSMB laser modulators.
• To establish and validate a cavity power coupling model.

Main Methods:

• Utilized D-shaped mirrors to mitigate modal instability.
• Investigated finesse reduction due to high-order mode damping.
• Developed a method to estimate mirror absorption coefficients via thermal effects.

Main Results:

• Achieved a cavity finesse of 16,518 ± 103.
• Estimated an average mirror absorption coefficient of 12 ppm.
• Experimental and simulation results for cavity power coupling showed close agreement.

Conclusions:

• The developed high-average-power enhancement cavity advances SSMB technology.
• Validated cavity power coupling models and mirror absorption estimation methods.
• Insights gained are crucial for designing and operating future high-power SSMB systems.