Y. Kang, H.X. Lu, et al.
Applied Physics Letters
We describe a simple solar-blind split-cathode photodiode for use in controlling the orientation of a nonlinear optical cyrstal such as β-barium borate (BBO) to maintain optimum conversion of pump light to tunable ultraviolet radiation in the 200-nm region. This device avoids the need for any wavelength filtering and is rugged, inexpensive and easy to build.