Development of a single-resonant optical parametric oscillator with tunable output from 218 nm to 322 nm

A single-resonant type-I β-Ba₂BO₄ (BBO) optical parametric oscillator (OPO) with a widely tunable output and a repetition rate of 100 Hz in the ultraviolet region has been reported. The system incorporates crystal switch technology, enabling continuous tunability in the ultraviolet spectral range from 218.7 nm to 322.5 nm, with a tuning range of 103.8 nm. The OPO component further enhances the system’s versatility, extending the tunable range from 409.9 nm to 709.0 nm, covering a continuous span of 399.1 nm. The OPO achieved a maximum conversion efficiency of 25.78% at 477.0 nm, with an average efficiency of approximately 13% across the 470–710 nm range. Additionally, the highest recorded energy output of the system at 239 nm is 205.1 µJ. Our study includes both theoretical and experimental analyses, with particular focus on the observed fluctuations in conversion efficiency throughout the experimental process.