Abstract

Materials suitable for nonlinear optics in the ultraviolet typically exhibit small nonlinear-optical coefficients. This makes applications in frequency conversion rather inefficient. To attain reasonable conversion efficiencies in the continuous wave (CW) regime, one may compensate for these small coefficients with field enhancement. Whispering gallery resonators are very promising for this purpose. Lithium tetraborate (LB4), as an example, allows collinear phase-matching for second harmonic generation (SHG) of 488 nm light. The generated 244 nm wavelength, for instance, finds applications in semiconductor inspection. However, the nonlinear coefficient of LB4 for this process is as small as d₃₁ = 0.073 pm/V [1].

© 2015 IEEE