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TThis figure uses multiple layers to show the energy-level structure of the Er3+ ion in a YAG crystal. All energy levels are represented by horizontal drop-down lines. The left layer shows all energy levels and other layers displays the sub-levels in a better view.
This figure is submitted by Dr. Van Rudd. Dr. Rudd works in Lockheed Martin Coherent Technologies, he is a research scientist working on various lasers.