Tunable high-power urea optical parametric oscillator

A tunable, high-power optical parametric oscillator (OPO), using a urea single crystal as the nonlinear medium, is described. This OPO may be tuned from 506 to 900 nm when pumped with the 355-nm output of a frequency-tripled, Q-switched Nd:YAG laser. An average power of 50 mW has been achieved, with conversion efficiencies exceeding 20% at 530 nm. The feasibility of increasing the average power to greater than 100 mW was demonstrated. High efficiency can be maintained while pumping with the near field of the Nd:YAG laser. The urea OPO is a compact, solid-state device that could be used for most laser applications requiring tunability between 500 and 1225 nm. The demonstrated high-peak power could provide efficient doubling or mixing into the 250-500-nm region, thus providing a convenient solid-state device for producing laser radiation from the UV to the near IR. Applications include spectroscopy, medicine, materials processing, nonlinear optics, and laser photochemistry.<>