Thermal effects in an ultrafast BiBO optical parametric oscillator at high average powers.

An ultrafast, high-average-power, extended-cavity, femtosecond BiBO optical parametric oscillator was constructed as a test bed for investigating the scalability of infrared parametric devices. Despite the high pulse energies achieved by this system, the reduction in slope efficiency near the maximum-available pump power prompted the investigation of thermal effects in the crystal during operation. The local heating effects in the crystal were used to determine the impact on both phase matching and thermal lensing to understand limitations that must be overcome to achieve microjoule-level pulse energies at high repetition rates.