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Waveguides are important optical elements for sensing , illumination , artistic displays , integrated optical circuits , as well as teaching aids for demonstrating important optical phenomena .
 optical elements, sensing, optical, as, as, optical
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: manufacturing standard, machanical property, manufacturing process, material, engineering feature, process parameter, machine or equipment, application, process characterization, enabling technology, biomedical, concept or principle 
Text: {0} 
Answer:
 optical elements, sensing, optical, as, as, optical