This text will connect light-matter interactions and device performance. Useful for those studying or working with optoelectronic devices, optical materials, and nano-plasmonics, this book provides the fundamental knowledge of light-matter interactions in the optical wavelength range, which can establish the required techniques to investigate the working mechanisms of solar cells, light-emitting diodes, and nano-plasmonic devices. The functions of various optical components will be explained, which can provide the required knowledge to design optical measurement systems. Video of optical simulations will accompany this text.