Beta-barium Borate as a Pockels Cell for Excimer Lasers

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A novel nonlinear crystal, beta- barium borate (BB0), is proposed to be used as a Pockels cell for excimer lasers operating at 248 nm for the generation of high peak intensities. At present, a variety of material related problems of existing commercial Pockels cells have limited their use below 300 nm. The researchers at Quantum Technology Inc. grow their own BB0 crystals, and these crystals will be used in the experiments. It has good transmission down to 190 nm, has a high damage threshold of 4 GW/cm2 and can handle average powers up to 100 watts at 1064 nm. A BBO Pockels cell will be designed at 248 nm utilizing the r11 electro- optic coefficient. The crystal will be oriented such that the field is applied along (100) and the beam will propagate along (001). The maximum length of BBO crystals presently available is limited to 10 mm. With a crystal dimension 5 x 5 x 10 mm3, the theoretical half-wave voltage is expected to be 14 KV. However, by employing two identical crystals optically in series and electrically in parallel, the half- wave voltage of 14 KV will be reduced to 7 KV at 248nm. BBO crystals grown at QTI will be used in this work. A BBO Pockels cell will be assembled and completely characterized for use at 248 nm.