Frequency doubling in KB5O8⋅4H2O and NH4B5O8⋅4H2O to 217.3 nm

Abstract
We have produced tunable phase‐matched second‐harmonic radiation in a KB5O8⋅4H2O crystal between 217.3 and 234.5 nm. Phase matching was achieved by crystal rotation. We also studied frequency doubling in NH4B5O8⋅4H2O.