Labour of light in everyday life

And God said, Let there be light and there was light. Although from the motto this work would rather look like a pure philosophical one it is actually based on applied science. Labour of light depicts its involvement in some major fields of everyday life and we illustrate it with our results in applications of optoelectronics and photonics. This work spans from materials such as wide gap semiconductors (e.g. nitrides, oxynitrides, germanium carbide), glasses with embedded semiconductor nanoparticles (e.g. CdSe) and organics, devoted to sensing and measuring devices to laser applications in medicine for cure and monitoring.