SEDL / STP / STP799-EB / STP37250S

Effects of Deuterium Treatments on the Optical Properties of Fused Silica

Kumar, B
University of Dayton Research Institute, Dayton, Ohio

Fernelius, NC
University of Dayton Research Institute, Dayton, Ohio

Detrio, JA
University of Dayton Research Institute, Dayton, Ohio

Pages: 5    Published: Jan 1983

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Abstract

Flame produced fused silica, the process used by all American manufacturers, contains a large amount of OH⁻. The fundamental OH⁻ vibration in SiO² is at 2.75 μm and its first overtone is at 1.38 μm. Much of the optical absorption at 1.3 μm is due to the wing of the 1.38 μm absorption band. Stone and Burrus^[1] described a deuterium treatment given optical fibers to transform the OH⁻ absorption to OD⁻ whose fundamental is at 3.72 μm and first overtone at 1.85 μm. Here we describe some related treatments given to Suprasil II window samples. Spectral traces show that the 1.38 μm absorption peak is diminished while a new absorption peak appears at 1.85 μm. Similar changes appear in the spectrum between 2 and 4 μm. 1.3 μm laser rate calorimetry performed before and after treatment on the sample showing the most complete H↔D exchange exhibited a drop in absorption value to about 1/5. Thus we conclude that over 80% of the optical absorption in Suprasil II at 1.3 μm is due to the OH⁻ molecule. The method offers a way of improving the performance of flame produced fused silica windows used at 1.3 μm.