Absorption coefficient of a 500nm layer of GaN on a sapphire substrate

Write a research paper on how you would measure the “Absorption coefficient of a 500nm layer of GaN on a sapphire substrate” It should be a 2 side document describing how¬† the measurement would be performed and including an estimate of the answer or range of answers that might be reasonable. The document should be presented like a short scientific paper, with abstract, introduction, method section, discussion, summary and references. Figures, schematics and tables should be included as appropriate. Word-processed document, either 1 or 2 column, minimum font size 11pt and is strictly limited to 2 sides.