Second-harmonic generation to 2048 Å in Β-Ba<inf>2</inf>O<inf>4</inf>

\Beta -BaB 2 O 4 has been found to be phase matchable for second-harmonic generation down to 2048 Å at room temperature. Sellmeier's equations, which are highly accurate from 1.064 μm to 2050 Å, are reported.